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Manual - Group of Computational Hydrosystems

1. I K cross section J K cross section 2 288 03 2 072E 03 1 100E 01 44 15 1 1 3418E 01 1 9761E 07 9 2067E 09 number of particles current time step current stress period vertical pore velocity at the cell J I K horizontal pore velocity at the cell J I K head at the cell J I K position of the mouse cursor in cell indices J I K Y position of the mouse cursor in real world coordinates x v z Fig 4 5 The PMPATH modeling environment 4 2 PMPATH Modeling Environment Processing Modflow 183 Tool bar The tool bar provides quick access to commonly used commands in the PMPATH modeling environment You click a button on the tool bar once to carry out the action represented by that button To change the current layer or the vertical local coordinate click the corresponding edit field in the tool bar and type the new value then press ENTER See eq 4 7 for the definition of the vertical local coordinate The following table summarizes the use of the tool bar buttons of PMPATH Table 4 1 Summary of the tool bar buttons of PMPATH Button Action Open Model allows a user to open a model created by PMWIN Set Particle allows a user to place particles in the model domain Erase Particle provides a way to delete particles Zoom In allows you to
2. Fig 6 21 Configuration of the hypothetical model after McDonald et al 1991 6 2 3 Simulation of a Two Layer Aquifer System 252 Processing Modflow Two steady state solutions were obtained to simulate natural conditions and pumping conditions The steady state solutions were obtained through a single simulation consisting of two stress periods The first stress period simulates natural conditions and the second period simulates the addition of pumping wells with extraction rates of 30000 ft d 850 m d The simulation is declared to be steady state so no storage values are specified and each stress period requires only a single time step to produce a steady state result The PCG2 Package is used to solve the flow equations for the simulations Determination of the wetting threshold THRESH see Modflow Wetting Capability often requires considerable effort The user may have to make multiple test runs trying different values in different areas of the model In many cases positive THRESH values may lead to numerical instability and therefore the user should try negative THRESH values first 6 2 3 Simulation of a Two Layer Aquifer System Processing Modflow 253 6 2 4 Simulation of a Water Table Mound resulting from Local Recharge Folder pm5 examples basic Woasic4 Overview of the Problem This example is the second test problem of the BCF2 package Localized recharge to a wat
3. Plane 2 Fig 3 41 Initial placement of moving particles adopted from Zheng 1990 a Fixed pattern 8 particles are placed on two planes within the cell block b Random pattern 8 particles are placed randomly within the cell block 3 6 3 MT3D 124 Processing Modflow e e e e e e Fixed pattern 1 Fixed pattern 2 Fixed pattern 3 e e e e e e eo o e e e o oe e e e e oe e e e 2 o Fixed pattern 4 Fixed pattern 5 Fixed pattern 6 Fig 3 42 Distribution of initial particles using the fixed pattern adopted from Zheng 1990 If the fixed pattern is chosen the number of particles placed per cell NPL and NPH is divided by the number of vertical planes NPLANE to yield the number of particles to be placed on each vertical plane which 1s then rounded to one of the numbers of particles shown here MT3D gt Dispersion The following values must be specified for each layer in the Dispersion Package MT3D MT3DMS dialog box Fig 3 43 The longitudinal dispersivity for each finite difference cell is specified in the Data Editor gt is the ratio of the horizontal transverse dispersivity to the longitudinal dispersivity gt TRPV is the ratio of the vertical transverse dispersivity to the longitudinal dispersivity gt DMCOEF is the effective molecular diffusion coefficient D LT see eq
4. m O OOGO Gl Ol Gl Gl Gl 4 4 ooccdoolsisisais Simulation Flow Type C Steady State 0 days X Auto Update Period Length Time Unit otal Simulation Time 1 46 3 days Load OK Cancel Help Fig 3 16 The Time Parameters dialog box gt Period Active Length Time Step In MODFLOW the simulation time is divided into stress periods which are in turn divided into time steps Check the Active flag to activate a stress period For each stress period you have the option of changing parameters associated with head dependent boundary conditions in the River Stream Drain Evapotranspiration General Head Boundary and Time Variant Specified Head Boundary packages as well as the recharge rates in the Recharge package and pumping rates in the Well package For transport simulations you can change source concentration associated with the fluid sources and sinks The length of stress periods and time steps 1s not relevant to steady state flow simulations However if you want to perform transport simulations at a later time you must specify the actual period length gt Multiplier FLOW MODFLOW allows the time step to increase as the simulation progresses It uses the following formulae to increase the lengths of time steps as a geometric progression 3 5 The Parameters Menu Processing Modflow 75
5. TO 3D96 AND LA TO MT3D95 AND LATER Modflow Program c program files pm5 modflw96 Ikmt2 modflow2 exe Basic Package c ApmwinsexampleskpmexXpmb5 1Xbas da Block Centered Flow BCF1 2 c ApmwinkexampleskpmexXpmb TXbcf dat Output Control c ApmwinkexampleskpmexXpmb5 1Xoc dat Time Yariant Specified Head cApmwinXexamplesxXpmexXpmb TVchd1 di Recharge cApmwinXexamplesxpmexipmb Tirch dat Solver PCG 2 c pmwinexamples pmex pm5_1 pcqe2 d Modpath Vers 1 x c pmwinexamplespmex pm5_1 main di Modpath Vers 3 x c pmwinexamplespmex pm5_1 main30 Options Regenerate all input files for MODFLOW Check the model data Generate input files only don t start MODFLOW Don t generate MODPATH files anyway Cancel Help Fig 3 33 The Run Modflow dialog box 3 6 MODFLOW 110 Processing Modflow Table 3 4 Versions and filenames of MODFLOW Version Filename MODFLOW96 MODFLOWOS6 INTERFACE TO MT3D 1 XX MODFLOWO S6 INTERFACE TO MT3D96 MODFLOW INTERFACE TO MT3DMS MODFLOW DENSITY PACKAGE FROM KIWA PMWIN 4 X interface to MT3D 1 XX PMWIN 4 X interface to MT3D96 pmhome modflw96 usgs modflw96 exe pmhome modflw96 lkmt1 modflow1 exe pmhome modflw96 lkmt2 modflow2 exe pmhome mt3dms modf exe pmhome modflow density modden exe pmhome modflow lkmt1 mflowpm4 exe pmhome modflow lkmt2 mflowpm4 exe pmhome is the folder in which PM
6. equations in upper part of A This is the maximum number of equations in the upper part of the equations to be solved This value impacts the amount of memory used by the solver If specified as 0 the program will calculate the value as half the number of cells in the model which is an upper limit The actual number of equations in the upper part will be less than half the number of cells whenever there are no flow and constant head cells because flow equations are not formulated for these cells The solver prints the actual number of equations in the upper part when it runs The printed value can be used in future runs in order to minimize memory usage gt equations in lower part of A This is the maximum number of equations in the lower part of the equations to be solved This value impacts the amount of memory used by the solver If specified as 0 the program will calculate the value as half the number of cells in the model which is an upper limit The actual number of equations in the lower part will be less than half the number of cells whenever there are no flow and constant head cells because flow equations are not formulated for these cells The solver prints the actual number of equations in the lower part when it runs The printed value can be used in future runs in order to minimize memory usage 3 6 1 MODFLOW 104 Processing Modflow gt Max band width of AL This value impacts the amount of memory used by t
7. 5782626 Fig 2 27 Simulated concentration at 3 years in the third layer Concentration Time Curves Graph Style Linear g 47E 7 C Semi Log Data Types Min tima Min value M Calculated 2000000 0 Iv Observation Data gt gt tima value 9 46720E 07 800 Iv Draw horizontal grid Ticks Ticks M Draw vertical grid _ Hp 10 10 Auto Adjust Min Max Close Fig 2 28 Concentration time curves at the observation boreholes 2 2 Perform Transport Simulation with MT3D Processing Modflow 39 2 2 2 Perform Transport Simulation with MOC3D In MOC3D transport may be simulated within a subgrid which is a window within the primary model grid used to simulate flow Within the subgrid the row and column spacing must be uniform but the thickness can vary from cell to cell and layer to layer However the range in thickness values or product of thickness and effective porosity should be as small as possible The initial concentration must be specified throughout the subgrid within which solute transport occurs MOC3D assumes that the concentration outside of the subgrid 1s the same within each layer so only one value is specified for each layer within and adjacent to the subgrid The use of constant concentration boundary condition has not been implemented in MOC3D gt set the initial concentration 1 Choose MOC3D Initial Concent
8. Position of the mouse cursor x y Position of the grid cursor J I nonstant her d bonndnry hy 16 10 n ime independent Mesh Size L rem era N Refinement of row I Refinement of column J Width of row I Width of column J Fig 3 3 The Grid Editor n 997 7953 1194 331 3 The Grid Editor 58 Size Column Refinement Column Row Layer Number of Columns 30 Number of Rows 30 Current Position Column Row 15 13 Processing Modflow OK Cancel Help Fig 3 4 The Size of Column and Row dialog box The following table summarizes the use of the tool bar buttons of the Grid Editor Table 3 2 Summary of the tool bar buttons for the Grid Editor Button Action leave editor Leave the Grid Editor e 9 Le f while you move the mouse while you move the mouse zoom out Displays the entire worksheet assign value Allows you to move the grid cursor and assign values zoom in Allows you to drag a zoom window over a part of the model domain rotate grid To rotate the model grid click the mouse on the worksheet and hold down the left button shift grid To shift the model grid click the mouse on the worksheet and hold down the left button duplication on off If duplication is turned on the size of the current row or column will be copied to all rows or columns passed by the grid cursor Duplication
9. You do not need to click this button if its relief 1s already sunk Click the mouse cursor on a desired position to anchor one end of a line 3 Move the mouse to another position then press the left mouse button again Repeat steps 2 and 3 until the zone is closed or press the right mouse button to abort gt To delete a zone 1 Click the assign value button You do not need to click this button if its relief 1s already sunk 2 Move the mouse cursor into a zone The boundary of the zone will be highlighted The value s of the current zone will be shown on the status bar 3 Press the Del key gt assign new value s to a zone 1 Click the assign value button l You do not need to click this button 1f its relief is already sunk 2 Move the mouse cursor into a zone The boundary of the zone will be highlighted The value s of the current zone will be shown on the status bar 3 2 The Data Editor Processing Modflow 63 3 Press the right mouse button once The Data Editor displays a dialog box 4 In the dialog box type new value s then click to transfer the new zone value s to cells Note that PMWIN always uses cell data for computations and if zone data are not transferred to the grid cells the original values in the cells are used gt To modify a zone 1 You may shift a vertex of a zone by pointing the mouse cursor at the vertex node and pressing down the left mouse button while moving t
10. select a species and click Editto editthe concentration data For single species simulation activate only one species Ns Description 2 MAGN ME ATE GE Fig 3 48 The Initial Concentration MT3DMS dialog box 3 6 4 MT3DMS Processing Modflow 133 MT3DMS gt Initial Concentraion At the beginning of a transport simulation MT3DMS requires the initial concentration of each active species at each active concentration cell 1 ICBUND gt 0 MT3DMS Advection The available settings of the Advection Package MT3DMS dialog box Fig 3 49 are described below Note that the simulation parameters except the Courant number in the table of this dialog box are only required when the method of characteristics or its variants see MT3D gt Advection for details is selected Advection Package MT3DM3 LX Solution Scheme Hybrid MOC MMOC HMOC Simulation Parameters Max number of total moving particles MXPART 5000 Courant number PERCEL 0 75 Concentration weighting factor D 0 5 Negligible relative concentration gradient DCEPS 0 00001 Pattern for initial placement of particles NPLANE No of particles per cell in case of DCCELL lt DCEPS NPL No of particles per cell in case of DCCELL gt DCEPS Minimum number of particles allowed per cell NPMIN Maximum number of particles allowed per cell NPMAX Pattern for placement of particle
11. 0 34 0 30 Geer 9 23 oz 0 17 0 15 8 13 8 11 5 10 0 09 0 31 0 30 0 29 B 27 B 24 B 22 8 18 8 15 8 11 0 06 0 02 90 94 90 P 76 0 09 0 06 0 04 0 01 rd face 7 09 7 04 rg P4 Tg 2 54 7 50 V4 45 rdd de Bb B1 rrd rd 7 56 FAE 7 39 E pga BE 7 14 41 70 bb h5 hl 5b 2 51 7 45 7 39 Pe P25 LI 7 10 7 03 6 56 6 59 6 54 6 75 6 75 b fe 4b 45 de 34 feed de 7 15 7 06 6 56 6 59 6 80 6 7 6 56 6 49 b 43 5 38 b 3b 6 35 fd 7 26 7 23 8 7 14 70 7 00 6 41 6 5 6 61 6 50 6 40 6 30 b 21 6 13 6 07 6 02 8 98 5 46 T 7 01 6 95 5 87 b B8 6 60 6 57 6 45 6 33 6 20 6 06 5 96 5 56 5 58 5 58 5 56 5 34 6 52 5 83 5 84 bf 5 58 6 56 6 46 6 33 5 13 6 05 5 40 5 75 5 6 5 49 5 38 5 2 5 16 5 14 6 80 b ro b 4 5 53 b 51 6 40 b 2b 6 11 5 34 Bu 5 59 5 42 5 2h 5 10 4 97 4 06 476 4 72 4 53 5 58 5 55 b 47 b 3b b 23 6 07 5 90 5 70 5 50 5 26 5 06 4 00 4 70 4 54 4 41 4 31 4 25 4 21 5 58 6 56 6 5 5 44 6 35 b 23 6 08 5 9 5 70 5 46 5 23 4 97 4 2 4 49 4 28 4 09 3 43 3 91 3 4 3 7 6 5 5 48 5 43 b 3b b 2b 6 13 5 46 bf 5 54 5 27 4 97 4 55 4 35 4 07 3 84 j b 3 40 Jer
12. Problem Type The choice of problem type affects the efficiency of solution significant work can be avoided if it is known that A remains constant all or part of the time Linear indicates that the flow equations are linear To meet the linearity requirement all model layers must be confined and there must be no formulations that change based upon head such as seepage from a river changing from head dependent flow to a constant flow when head drops below the bottom of the riverbed Examples of non linearity are cases with riverbed conductance drain conductance maximum evapotranspiration rate evapotranspiration extinction depth gerneral head boundary conductance and reservior bed conductance Nonlinear indicates that a non linear flow equation is being solved which means that some terms in A depend on simulated head Example of head dependent terms in A are 3 6 1 MODFLOW Processing Modflow 105 transmissivity for water table layers which is based on the saturated thickness flow terms for rivers drains and evapotranspiration of they convert between head dependent flow and constant flow and the change in storage coefficient when a cell converts between confined and unconfined When a non linear flow equation is being solved external iteration is normally required in order to accurately approximate the non linearities Note that when non linearities caused by water table calculations are part of a simulation there are not necessari
13. STT CBC Elevation of the top of the streambed SWI CBC Width of the stream channel in each reach 298 CBC Parameter numbers associated with stream cells 514 ZONE Zone file Time Variant Specified Head CHD Package Extension Type Description CH1 CBC A non zero value indicates a CHD cell CH2 CBC Head at the beginning of a stress period Start head CH3 CBC Head at the end of a stress period End head C1Z ZONE Zone file Well Package Extension Type Description WEL CBC Volumetric recharge rate of wells 299 CBC Parameter numbers associated with Well cells WEZ ZONE Volumetric recharge rate of wells MTSD Advection Package Extension Type Description ADV ASCII User specified settings for the Advection Package MT3D Dispersion Package Extension Type Description DPS ASCII User specified settings for the Dispersion Package TAL CBC Longitudinal dispersivity M1 1 ZONE Longitudinal dispersivity MT3D Chemical Reaction Package Extension Type Description CHE ASCII User specified settings for the Chemical Reaction Package C91 CBC Bulk density only used by MT3D96 C92 CBC First sorption constant only used by MT3D96 C93 CBC Second sorption constant only used by MT3D96 C94 CBC First order rate constant for the dissolved phase only used by MT3D96 C95 CBC First order rate constant for the sorbed phase only used by MT3D96 Z91 Zone Zone file containing the chemical reaction parameters for MT3D96
14. lumped to the right hand side of the system of transport equations Omitting the cross terms represents a method of approximation which 1s highly efficient MTSDMS Output Control MT3DMS and MT3D have the same output structure See MT3D Output Control for the use of the Output Control MT3D MT3DMS dialog box Fig 3 44 MT3DMS Run The available settings of the Run MT3DMS dialog box Fig 3 52 are described below MT3DMS Program contains the full path and filename of the MT3DMS code which will be called by PMWIN The default code 15 the version DoD_3 00 A developed by Zheng and Wang 1998 If you want to use a compiled version located in an other position click the open file button and select the desired code from a dialog box The File Table PMWIN uses the user specified data to generate input files of MT3D Description gives the name of the packages used in the flow model The path and name of the input files are shown in Destination File PMWIN generates an input file only if the corresponding Generate flag is checked You may click on a flag to check or uncheck it Normally you do not need to worry about these flags as PMWIN will take care of the settings Options Regenerate all input files for MT3DMS You should check this option if the input files have been deleted or overwritten by other programs Generate input files only don t start MT3DMS Check this option if you do not want to run MT
15. to choose the settings of the contours The contour plot for the first model layer should look similar to that in Fig 6 11 Granite Hills T T NN SW MAF M Mj CREE LN N eM South Granite Hills Fig 6 11 Steady state head distribution in the first model layer 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River 10 11 12 15 14 15 Processing Modflow 24 To delineate the capture zones of the pumping wells Start PMPATH by Models PMPATH Pathlines and contours PMPATH will load the current model automatically We will place particles around the pumping wells and examine their 10 year capture zones Move to Layer 3 by pressing the Page Down PgDn key twice Click on the button and drag a small box around the cell containing Well 1 by holding down the left mouse button and moving the mouse When you release the mouse button the Add New Particles dialog box appears edit Particles on circles such that the number of particles is equal to 15 the radius R 80 and the number of planes NK 3 Click the Properties tab and change the color of new particles to Blue Click on OK to exit the Add New Particles dialog box Using a similar procedure add particles around Well 2 and Well 3 Make each of these a different color say Green and Black To display the hydraulic heads and a transverse and longitudinal cross section open t
16. 09 8 09 8 09 8 09 8E 03 8E 09 8 09 8 09 8 09 8 09 8E 03 8E 09 8 09 8 09 8 09 8 09 8E 03 8E 09 E09 _ 8E 09 8E 09 8E 09 8E 09 8E 09 8E 09 8 09 8 09 8 09 8E 03 8 09 8 09 8 09 8 09 8 09 8E 03 8 8 09 8 09 8 09 8 09 8 09 8E 09 a 8 09 8E 09 09 09 09 8 09 8 09 8 09 8 09 8 09 8 09 8E 03 8E 03 8 09 8 09 8 09 8 09 8E 09 8E 09 8 09 8 09 8 09 8 09 8E 09 8E 09 8 09 8 09 8 09 8 09 8E 09 8E 09 8 09 8 09 8 09 8 09 8E 09 8E 09 8 09 8 09 8 09 8 09 8E 09 aF na RF f18 RF f18 RF f18 AF N4 RF f18 Load Save OK Cancel Help Fig 3 58 The Browse Matrix dialog box 3 8 The Value Menu 162 Processing Modflow To load an ASCII Matrix or a SURFER GRD file Click the Load button The Load Matrix dialog box appears Fig 3 59 Click and select a file type 1 e ASCII Matrix or SURFER GRD and a file from an Open File dialog box Specify the starting position As shown in Fig 3 60 the starting position indicates the column and row at which a matrix will be loaded Numbers of rows and columns of the loaded matrix need not to be identical to those of the finite difference grid This allows you to replace only part of the cell data by the matrix For example you can use the Field Generator to generate a matrix with heterogeneously distributed data from statistic parameters and load it into the grid
17. 569 p Bear J and A Verruijt 1987 Modeling groundwater flow and pollution D Reidel Publishing Dordrecht Holland Behie A und P Forsyth Jr 1983 Comparison of fast iterative methods for symmetric systems IMA J of Numerical Analysis 3 41 63 Cheng X and M P Anderson 1993 Numerical simulation of ground water interaction with lakes allowing for fluctuating lake levels Ground Water 31 6 929 933 8 References 328 Processing Modflow Chiang W H W Kinzelbach and R Rausch 1998 Aquifer Simulation Model for Windows Groundwater flow and transport modeling an integrated program Gebr der Borntraeger Berlin Stuttgart ISBN 3 443 01039 3 Chiang W H and W Kinzelbach 1993 Processing Modflow PM Pre and postprocessors for the simulation of flow and contaminant transport in groundwater system with MODFLOW MODPATH and MT3D Chiang W H and W Kinzelbach 1994 PMPATH for Windows User s manual Scientific Software Group Washington DC Chiang W H and W Kinzelbach 1998 PMPATH 96 An advective transport model for Processing Modflow and Modflow Clement T 1998 RT3D A modular computer code for simulating reactive multi species transport in 3 dimensional groundwater systems Battelle Pacific Northwest National Laboratory Richland Washington 99352 Cooper H H Jr and M I Rorabaugh 1963 Ground water movements and bank storage due to flood stages in surface streams U S
18. Animation This menu item is only activated by using the Presentation Tools Presentation tool for creating or displaying an animation sequence Before creating an animation sequence you should use the Enivironment Option and Maps Option dialog boxes refer to the Options menu for details to make sure that the model grid maps and contours are set properly gt create an animation sequence 1 Select Animation from the File menu An Animation dialog box appears 2 Inthe Animation dialog box click the open file button A Save File dialog box appears Select an existing frame file or specify a new base file name for the frame files in the dialog box then click Open Like a movie an animation sequence is based on lots of frames Each frame is saved by using the filenames fn xxx where fn 1s the Frame File specified above and xxx is the serial number of the frame files Note that you cannot save the animation files in the same folder as your model data So you need first to create a new folder or select another folder for the files 3 Check or uncheck Create New Frames Check Create New Frames if you want to create a new animation sequence Uncheck it if you want to playback a saved sequence 4 Select an appropriate Result Type and Display Time s Five result types are avaliable including Hydraulic Head Drawdown and Concentration calculated by MT3D MOC3D and MT3DMS Display Time is the display duration for e
19. Boundary Condition IBOUND Modflow An IBOUND array is required by the flow model MODFLOW The IBOUND array contains a code for each model cell A positive value in the IBOUND array defines an active cell the hydraulic head 1s computed a negative value defines a fixed head cell the hydraulic head 1s kept fixed at a given value and the value 0 defines an inactive cell no flow takes place within the cell It is suggested to use 1 for active cells for inactive cells and 1 for fixed head cells For fixed head cells the initial hydraulic head remains the same throughout the simulation The initial hydraulic head is specified by choosing Starting Values Hydraulic Heads from the Parameters menu A fixed head boundary exists whenever an aquifer 1s in direct hydraulic contact with a river a lake or a reservoir in which the water level is known It 1s important to know that a fixed head boundary provides inexhaustible supply of water A groundwater system may get as much water as necessary from such a boundary without causing any change in boundary head In some situations this may be unrealistic Therefore care must be taken when using fixed head boundaries Consider to use the General Head Boundary or the Time Variant Specified Head packages if the hydraulic head at the fixed head boundary varies with time If you intend to use the transport model MOC3D you should be aware that MOC3D allows you to specify zones along the fixed head bounda
20. OUT to the upper adjacent layer EXCHANGE LOWER gives the flow rate coming from 2 Run a Steady State Flow Simulation Processing Modflow 21 IN or going to OUT to the lower adjacent layer For example consider EXCHANGE LOWER of ZONE 1 and LAYER 1 the flow rate from the first layer to the second layer is 2 587256E 03 m s The percent discrepancy in Table 2 3 is calculated by 100 IN OUT TabW 2 3 fram the Water Budget Calculator FLOWS ARE CONSIDERED IHE UNIT OF THE FLOWS L5 TIME STEP ZONE 1 LAYER FLOW TERM STORAGE CONSTANT HEAD HORIZ EXCHANGE EXCHANGE UPPER EXCHANGE LOWER WELLS DRAINS RECHARGE SUM OF THE LAYER LAYER ZONE 2 FLOW TERM STORAGE CONSTANT HEAD HORIZ EXCHANGE EXCHANGE UPPER EXCHANGE LOWER WELLS DRAINS RECHARGE SUM OF THE LAYER lt Eu IN 1 OF STRESS PERIOD IN 0000000 00 8407618E 04 0000000 00 0000000 00 0000000 00 0000000 00 0000000 00 6880163E 03 8720924E 03 IN 0000000 00 0027100 03 0000000 00 5872560E 03 0000000 00 0000000 00 0000000 00 0000000 00 5899659E 03 2 2 IF THEY ARE ENTERING A SUBREGION OOrRrNODAON OC O OHH O OUT 0000000 00 4361895E 04 0000000 00 0000000 00 5872560E 03 0000000E 10 0000000 00 0000000 00 8308749E 03 OUT 00000
21. Processing Modflow A Simulation System for Modeling Groundwater Flow and Pollution Wen Hsing Chiang and Wolfgang Kinzelbach December 1998 Contents Preface 1 Introduction 1 System RCGUIFCINCHIS 22 2209 ohne ABUS euh ows ahead oes he oe ee 4 4 VADE hues hoe bos hie hae he 4 5 2 Your First Groundwater Model with PMWIN 7 2 1 Runa Steady State Flow Simulation 8 2 2 Simulation of Solute Transport dee bewat ate ds 32 2 2 1 Perform Transport Simulation with MT3D 33 2 2 2 Perform Transport Simulation with MOC3D 39 2 3 Automatic Calibration 44 2 3 1 Perform Automatic Calibration with PEST 46 2 3 2 Perform Automatic Calibration with 49 DAL ME EDO DTP PPP 51 3 The Modeling Environment 53 i s6nimuoM m 55 32 Ene Data socseustauste uaa iow ss oo ewes a sl eee awe dd td S 59 3 2 1 The Cell by Cell Input Method 61 2424 2 The Zone Input Method doe RC DR ds ed 62 3 2 3 Specification of Data for Transient Simulations 63 or NCPC cositas en Ata ee Ada MEM E I S
22. The analytical solution of the seepage rate after the Dupuit assumption is hf hi h h K 2L 2 L 6 2 where B is the length of the dam L is the thickness of the dam K is the hydraulic conductivity h and h are the heads at the uptream and downstream sides of the dam respectively The modified form of the analytical solution is Darcy s Law with a mean transmissivity of h h 2 For this example with h 10 m h 2 m L 10m 100 m and K 1 x 10 m s the seepaga rate is exactly equal to 4 8 x 10 m s 6 5 3 Seepage Surface through a Dam 288 Cells in the l direction 6 5 3 Seepage Surface through a Dam _ i e 3 1 10 9 75 9 75 9 74 9 74 9 74 9 74 d ra 3 73 Bre g r2 9 7 9 7 4 70 4 70 4 69 4 69 4 69 4 69 4 66 3 58 4 50 4 50 4 50 4 49 9 49 9 46 9 47 9 46 9 45 9 44 3 43 9 42 3 41 4 40 3 394 3 394 9 36 9 37 9 37 9 37 4 9 25 9 25 9 25 9 24 923 dee 9 21 9 20 3 18 9 16 9 15 9 13 9 12 4 10 4 09 4 06 4 0 4 06 4 06 4 06 Processing Modflow Cells in the J direction EE Ee Ee ERR RU RE EE 80 4 01 4 01 4 00 0 99 0 90 0 97 0 95 0 99 0 91 0 09 0 07 0 05 doe 0 01 g 7g Gf g 75 g 74 0 74 B 7 Gf B rb 6 75 B 73 0 69 5 6 0 56 0 56 g 53 o da 0 46 0 44 0 43 B 42 B 42 B 54 B 53 B be 5 5 0 49 0 46 0 44 0 40
23. determined by linear interpolation using the starting and ending stages for the stress period The interpolated reservoir stage corresponds with the simulation time at the end of a model time step Stage Time Table of Reservoirs x Reservoir Description o OO MH This is the first reservoir The secondreservoir Cancel E Ese Help Save Clear Output Options Make stage volumn area table for reservoirs Use 10 points in constructing the table Fig 3 22 The Stage Time Table of Reservoirs dialog box MODFLOW River The River package is used to simulate the flow between an aquifer and a surface water feature such as rivers lakes or reservoirs Rivers are defined by using the River Package dialog box of the Data Editor to assign the following values to the model cells Hydraulic conductance of the riverbed Ca LT Head in the river Hay L Elevation of the bottom of the riverbed Rgo7 L and Parameter Number After specifying the values they are shown from left to right on the status bar The parameter number is used to assign Cay as a parameter for an automatic calibration by the inverse models PEST see PEST gt Parameter List gt Parameter List For transient flow simulations involving several stress periods these values can be different from period to period If th
24. 1 ral d How LE i l E 4 T 4 L i s Ps d pec Fig 3 63 Defining iis and orientation of the worksheet and model erid Environment Options Appearance Coordinate System Contours Grid Position Worksheet Coordinate System Y our model grid Y Xo Y a Worksheet Size xt 0 A Rotation angle in degree X1 Y1 Display zones in cell by cell mode Ea aca Fig 3 64 The Coordinate System tab of the Environment Options dialog box 3 9 The Options Menu 168 Processing Modflow Ignore inactive cells If this box is checked the data of inactive cells will not be used for creating contours Parameter If you are editing a particular package in which a cell has more than one value for example the River package requires three values for each cell you can select the parameter type from this drawdown box PMWIN uses the data associated with the selected parameter type to create contours Contour level table You can click on each cell of the table and modify the values or you can click on the header button of each column of the table to change the values for all cells of the column Level To produce contours on regular intervals click the header of this column A Contour Levels dialog box allows you to specify the contour range and interval By default this dialog box displays the maximum and minimu
25. 2000E 03 RECHARGE 0 RECHARGE 0 0000 IOTAL OUT 464137 TOTAL OUT 9027E 03 IN OUT ZO ppm OUT 008E 07 PERCENT DISCREPANCY 0 PERCENT DISCREPANCY 0 01 Step 5 Calculate subregional water budget There are situations in which it is useful to calculate water budgets for various subregions of the model To facilitate such calculations flow terms for individual cells are saved in the file path BUDGET DAT These individual cell flows are referred to as cell by cell flow terms and are of four types 1 cell by cell stress flows or flows into or from an individual cell due to one of the external stresses excitations represented in the model e g pumping well or recharge 2 cell by cell storage terms which give the rate of accumulation or depletion of storage in an 2 Run a Steady State Flow Simulation 20 Processing Modflow individual cell 3 cell by cell constant head flow terms which give the net flow to or from individual fixed head cells and 4 internal cell by cell flows which are the flows across individual cell faces that is between adjacent model cells The Water Budget Calculator uses the cell by cell flow terms to compute water budgets for the entire model user specified subregions and flows between adjacent subregions gt calculate subregional water budgets 1 Choose Water Budget from the Tools menu A Water Budget dialog box appears Fig 2 8 For a steady state flow simulation you do not nee
26. 274 6 4 3 The Theis Solution Transient Flow to a Well in a Confined Aquifer 276 6 4 4 The Hantush and Jacob Solution Transient Flow to a Well ina Leaky Confined Aquifer 279 653 Geotechnical Problems RC i ES SS 262 6 5 1 Inflowof Water into an Excavation 282 6 5 2 Flow Net and Seepage under a Weir 284 6 5 3 Seepage Surface through Dam 286 uinum hte ae eae hee ee cae tan Sena eB 289 6 5 5 Compaction and Subsidence 292 6 5 Solute Transpo Sue ARE de ee aes s Pte diede degna 295 6 6 1 One Dimensional Dispersive Transport 295 6 6 2 Two Dimensional Transport in a Uniform Flow Field 297 6 6 3 Benchmark Problems and Application Examples from Liturature 300 6 7 Miscellaneous LODICS ad hea hea doo o deo deo dem eon een ecu 302 0 7 T Usine the Field IntetpolatOE 2 at ER E ERE A a S RS dt 302 6 7 2 An Example of Stochastic Modeling 306 Tz PDDENCICES E 309 Appendix 1 Limitation of PMWIN lere IIa 300 Appendix 2 Files and Formats sesa ee eoe eia des oe e a e pea Ro cd 310 Appendix 3 Input Data Files of the Supported Models 315 Appendix 4 Internal Data Files of PMWIN 0 20 ce
27. 7 Leave the Data Editor by File Leave Editor gt Yes 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River 236 Processing Modflow gt To specify the bottom elevation of each aquifer 1 Select Grid gt Bottom of Layers BOT PMWIN will ask if you want to use the Top of Layer 2 as the Bottom of Layer 1 and Top of Layer 3 as the Bottom of Layer 2 We will accept this Note that the elevation of the bottom of the layer 3 is 0 0 m so we do not need to change the default value 2 Leave the Data Editor by File Leave Editor Yes Specification of the geometry of the system is now complete all we need to do now is enter the physical parameters of the system South Granite Hills Fig 6 9 Boundary Conditions in layer 1 and layer 3 Granite Hills South Granite Hills Fig 6 10 Boundary Conditions in layer 2 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River Processing Modflow 237 Time parameters To specify the time parameters Select Parameters Time In the Time Parameters dialog box change the Simulation Time Unit to DAYS and check t
28. A Time Parameter file can be saved or loaded by the Time Parameter dialog box see section 3 3 3 File Format 1 Data NPER ITMUNI Appendix 2 Files and Formats Processing Modflow 313 The following data repeats NPER times 2 Data ACTIVE PERLEN NSTP TSMULT DTO MXSTRN TTSMULT Explanation of Fields Used in Input Instructions ALL DATA IN THE SAME RECORD ARE SEPARATED BY A COMMA OR BLANK NPER is the number of stress periods in the simulation ITMUNI indicates the time unit of model data It is used only for printout of elapsed simulation time It does not affect model calculations 0 undefined 1 seconds 2 minutes 3 hours 4 days 5 years The unit of time must be consistent for all data values that involve time For example if years is the chosen time unit stress period length timestep length transmissivity etc must all be expressed using years for their time units Likewise the length unit must also be consistent ACTIVE A stress period is active if ACTIVE 1 Set ACTIVE 0 if a stress period is inactive PERLEN is the length of a stress period It is specified for each stress period NSTP is the number of time steps in a stress period TSMULT isthe multiplier for the length of successive time steps The length of the first time step DELT 1 is related to PERLEN NSTP and TSMULT by the relation DELT 1 PERLEN 1 TSMULT 1 TSMULT NSTP DIO is the length of transport steps If 0 0 the length of transport
29. Chapter Al McDonald M G A W Harbaugh B R Orr and D J Ackerman 1991 BCF2 A method of converting no flow cells to variable head cells for the U S Geological Survey Modular Finite Difference Ground water Flow Model U S Geological Survey Open File Report 91 536 Denver Mejia and Rodriguez Iturbe 1974 On the synthesis of random field sampling from the spectrum An application to the generation of hydrologic spatial processes Wat Res Res 10 4 705 711 Moench A F and A Ogata 1981 A numerical inversion of the Laplace transform solution to radial dispersion in a porous medium Water Resour Res 17 1 250 253 8 References 252 Processing Modflow Neumann S P 1984 Adaptive Eulerian Lagrangian finite element method for advection dispersion Int J Numerical Method in Engineering 20 321 337 Oakes B D and W B Wilkinson 1972 Modeling of ground water and surface water systems I Theoretical relationships between ground water abstraction and base flow Reading Great Britain Reading Bridge House Water Resources Board 16 37 pp Pannatier Y 1996 Variowin Software for spatial data analysis in 2D Springer ISBN 0 387 94679 9 Poeter E P and M Hill 1998 Documentation of a computer code for universal inverse modeling U S Geological Survey Water Resources Investigations Report 98 4080 Pollock D W 1988 Semianalytical computation of path lines for finite differe
30. Fig 6 48 shows the flow net for the aquifer in the 6 5 2 Flow Net and Seepage under a Weir Processing Modflow 285 anisotropic case The flux through the aquifer is now only 2 5x10 m s m 21 6 m day m Note that in a homogeneous and anisotropic medium flowlines intersect head contours at right angle only where flow is parallel to one of the principal directions of hydraulic conductivity Embedded weir water table h 12 water table h 10 ee LEE EE EE T Ht LM Ka 4 TAKER e CHER CERT Sa EE CU 4 EE ER ERE EL ERE EI ULIS LT INET LL BS LA pu SS soe 6 CCoCN Ts Peace CCN IA ION 08 HEEL LC 7 LINE Canis see BINNEBNEN Sse Fig 6 48 Flowlines and calculated head contours for anisotropic medium 6 5 2 Flow Net and Seepage under a Weir 286 Processing Modflow 6 5 3 Seepage Surface through a Dam Folder pm5 examples geotechniques geo3 Overview of the Problem This example is adopted from Kinzelbach and Rausch 1995 This example demonstrates how to calculate the seepage surface using a vertical cross sectional model As shown in Fig 6 49 the length of the dam is 100 m the thickness and height are 10m
31. ITER1 Residual L 3 T 10 11 001 Printout From the Solver All available information C The number of iterations only Cancel C None Printout Interval 1 Help Fig 3 30 The Preconditioned Conjugate Gradient Package 2 dialog box 3 6 1 MODFLOW Processing Modflow 107 MODFLOW Solvers gt SIP The required parameters for the SIP package are specified in the Strongly Implicit Procedure Package dialog box Fig 3 31 The parameters are described below gt is the maximum number of iterations in one time step in an attempt to solve the system of finite difference equations gt IPRSIP is the printout interval for this package A positive integer is required The maximum head change positive or negative is saved in the run record file OUTPUT DAT for each iteration of a time step whenever the time step 1s an even multiple of IPRSIP This printout also occurs at the end of each stress period regardless of the value of IPRSIP gt NPARM is the number of iteration parameters to be used Five parameters are generally sufficient gt ACCL is the acceleration parameter It must be greater than zero and is generally equal to one gt Head Change L is the head change criterion for convergence When the maximum absolute value of head change from all cells during an iteration is less than or equal to Head Change iteration stops MODFLOW Solvers gt SSOR The required parameters for SSOR package
32. In addition PMWIN generates two batch files UCODE BAT and UCODE1 BAT in your model folder When all necessary files are generated PMWIN automatically runs UCODE BAT in a DOS window UCODEI BAT will be called by the inversion code After completing the parameter estimation process UCODE prints the optimized parameter values to the run record file UCODE ot in your model folder and automatically writes the optimized parameter values to the input files of MODFLOW BCF DAT WEL DAT etc The simulation results of MODFLOW are updated by using these parameter values Note that PMWIN does not retrieve the optimized parameter values into the data matrices Your PMWIN model data will not be modified in any way This provides more security for the model data because an automatic calibration process does not necessarily lead to success If you want to operate on a calibrated model you can import the calibrated MODFLOW model by choosing Convert Model from the File menu 3 6 6 Inverse Modeling 160 Processing Modflow Modflow Version MODFLOW96 INTERFACE TOMT3D96ANDLATER Modflow Program c program files pm5 modfw96 kmt2 modflow2exe 000000 Inverse Code E Aprogram files pm5 ucode mrdrive exe Destination File Basic Package c program files pm5 examples sample bas d Block Centered Flow BCF1 2 c program files pm5 examples sample1 bcf de Output Control c program files pm5 examples sample oc da
33. Iv Preconsolidation Heads from IBS1 Echo Print of Input Values Interface file to MT3D Output Frequency Stress period 1 Time step 1 Predefined Head Values For na flow cells 399 98 For cells which went dry 1E 30 Fig 3 28 The MODFLOW Output Control dialog box gt Hydraulic Heads are the primary result of a MODFLOW simulation Hydraulic heads in each finite difference cell are saved in the unformatted binary file HEADS DAT gt Drawdowns are the differences between the initial hydraulic heads and the calculated hydraulic heads Drawdowns in each cell are saved in the unformatted binary file DDOWN DAT gt Cell by cell Flow Terms are flow terms for individual cells including four types 1 cell by cell stress flows or flows into or from an individual cell due to one of the external stresses excitations represented in the model e g pumping well or recharge 2 cell by cell storage 3 6 1 MODFLOW Processing Modflow 101 terms which give the rate of accumulation or depletion of storage in an individual cell 3 cell by cell constant head flow terms which give the net flow to or from individual constant head cells and 4 internal cell by cell flows which are the flows across individual cell faces that 1s between adjacent model cells The cell by cell flow terms are used for calculating water budgets and for particle tracking and transport simulations by P
34. Load Save OK Cancel Fig 2 10 The Browse Matrix dialog box 2 1 Run a Steady State Flow Simulation 26 Processing Modflow Load Matrix x Click the open file button to select a file po m ean LA E NN Fig 2 11 The Load Matrix dialog box Environment Options x Coordinate System Contours 00000 qu 111150 7 amp D 2 nactive cell head cell IBOUND lt 0 ixed concentration cell ICBUND lt 0 General boundary head cell Discharge well Recharge well River or stream Horizontal flow barrier slurry wall orehole Digitized point Time variant specified head Environment Options lt 4 84805201 645 8485201 848528 200001 B 8 485281 8485280 300001 B 8 485281 8485280 400002 8485201 8485281 500002 B 8 485281 8485281 600002 B 8 485281 8485281 700003 B 841 8485280 800003 B 841 8485281 900003 B 8 485281 8485280 000004 8 485281 8485281 __tabeiFormet _ Restore Deteute toad Seve Look cence onem Fig 2 13 The Contours options of the Environment Options dialog box 2 Run a Steady State Flow Simulation Processing Modflow 21 i Processing Modflow SAMPLE1 PM5 File Value Options Help p oe __ im 1042789 B 70E FOQ Os z 98 80E F0d ce iD 1 1 EE LL 5 90E HO0 31 8 40E 00 8 3
35. MODFLOW Processing Modflow 103 MODFLOW Solvers gt DE45 Although a direct solver requires more memory and typically requires more computational effort than iterative solvers it may excute faster than an iterative solver in some situations The Direct Solution package Harbaugh 1995 uses Gaussian elimination with an alternating diagonal equation numbering scheme that is more efficient than the standard method of equation numbering It is the most efficient when solving small linear problems Use the Direct Solution DE45 dialog box Fig 3 29 to specify required parameters as described below gt iterations external or internal is the maximum number of iterations in each time step Set this number to if iteration is not desired Ideally iteration would not be required for direct solution however it is necessary to iterate if the flow equation is non linear see Problem type below or if computer precision limitations result in inaccurate calculations as indicated by large water budget error For a non linear flow equation each iteration is equally time consuming because the coefficient matrix A is changed each iteration and Gaussian elimination is required after each change This is called external iteration For a linear equation iteration is significantly faster because A is changed at most once per time step thus Gaussian elimination 15 required at most once per time step This 1s called internal iteration gt
36. MT3D Sink amp Source Mixing Package Extension Type Description TCH CBC Specified concentration at constant head cells TE CBC opecified concentration of evapotranspiration flux Appendix 4 Internal Data Files of PMWIN 322 TG TR TRC TST TW C54 C55 MT3 MT5 MT6 MT7 MT8 MT9 M10 Z54 MOC3D Extension MOC MPP C57 C58 757 758 MT3DMS Extension 231 260 261 290 401 430 431 460 461 490 601 630 631 660 661 690 801 830 831 860 861 890 1001 1030 1031 1060 1201 1230 331 360 361 390 501 530 531 560 ASCII ASCII CBC CBC ZONE ZONE CBC CBC CBC ZONE ZONE ZONE ZONE CBC ZONE ZONE ZONE ZONE Processing Modflow Specified concentration at general head boundary cells Specified concentration of river Specified concentration of recharge flux Specified concentration of stream Specified concentration of injection wells Flag indicates a Time variant specified concentration Concentration in a Time variant specified concentration cell Specified concentration of injection wells Specified concentration of river Specified concentration of evapotranspiration flux Specified concentration at general head boundary cells Specified concentration of recharge flux Specified concentration of stream Specified concentration at constant head cells Time variant specified concentration Description Subgrid initial concentration outside of t
37. MTADVI1 dialog box Fig 3 40 are described below Note that some of the simulation parameters are only required when a particular solution scheme 15 selected 3 6 3 MT3D 120 Processing Modflow Advection Package MTADY1 Simulation Parameters Max number of total moving particles MxXPART Courant number PERCEL Concentration weighting factor AD Negligible relative concentration gradient DCEPS Pattern for initial placement of particles NPLANE No of particles per cell in case of DCCELL lt DCEPS NPL No of particles per cell in case of DCCELL gt DCEPS NPH Minimum number of particles allowed per cell NPMIN Maximum number of particles allowed per cell NPMAX Multiplier for the particle number at source cells SRMULT OK Cancel Help Fig 3 40 The Advection Package MTADV1 dialog box gt Solution Scheme MT3D provides four solution schemes for the advection term including the method of characteristics MOC modified method of characteristics MMOC hybrid method of characteristics HMOC and upstream finite difference method The method of characteristics MOC scheme see MOC3D gt Advection was implemented in the transport models MOC Konikow and Bredehoeft 1978 and MOC3D and has been widely used One of the most desirable features of the MOC technique is that itis virtually free of numerical dispersion which creates serious difficulty in many numerical
38. PERLEN 1 TSMULT a 1 3 3 Delt m 1 TSMULT Delt m 3 4 where PERLEN is the length of a stress period T8MULT is the time step multiplier NSTP is the number of time steps and Delt m is the length of time step m in a stress period gt Transport Step size In the transport models MT3D MT3DMS and MOC3D each time step is further divided into smaller time increments called transport steps Because the explicit numerical solution of the solute transport equation has certain stability criteria associated with it the length of a time step used for a flow solution may be too large for a transport solution Each time step must therefore be divided into smaller transport steps For explicit solutions in MOC3D MT3D or MT3DMS i e when the Generalized Conjugate Gradient solver is not used the transport step sizes in the table are used for the simulation Considering stability criteria the transport models always calculate a maximum allowed transport step size Atna Setting the transport step size in the table to zero to a value max greater than will cause Atna to be used for the simulation For details about the stability max criteria associted with the explicit transport solution refer to Zheng 1990 or Konikow et al 1996 For implicit solutions in MT3DMS i e when the Generalized Conjugate Gradient solver is used the transport step sizes in the table are the initial transport step size i
39. PMWIN automatically runs MOC3D BAT in a DOS window During a simulation MOC3D writes a detailed run record to the listing file MOC3D LST MOC3D saves the simulation results in various files only if a transport simulation has been successfully completed See MOC3D Output Control for details about the output terms and the corresponding result files from MOC3D Run Moc3d Eq Moc3d Program c program files jpm5 moc3d moc3d exe gt Destination File Basic Package c pmbdata samplel bas dat Block Centered Flow c pmbdata sample bcf dat Output Control c pmSdata sample oc dat vvell c pm5data samplel wel dat Recharge c pm5data samplel rch dat Solver DE45 c pmbdata samplel de45 dat MOCS3D Main Package c pm5data samplet mocmain dat MOC3D concentration in recharge c pm5data samplel mocerch dat MOC3D observation well file c pmb5data samplel mocobs dat Options Regenerate all inputfiles Check the model data Generate input files only don t start MOC3D Don t generate MODPATH files anyway Cancel Help Fig 3 39 The Run Moc3d dialog box 3 6 3 MT3D MT3D gt Initial Concentration MT3D requires the initial concentration of each active concentration cell 1 e ICBUND gt 0 at the beginning of a transport simulation The values specified here are shared with MOC3D MT3D gt Advection The available settings of the Advection Package
40. PMWIN saves most of the user specified data in binary files by using the model name as the file name and the extensions given in the following lists Cell by cell data are saved in files indicated by CBC Zone data are saved in files indicated by ZONE The data files with the same file type e g CBC or ZONE are saved in the same format The source code in the Visual Basic 6 format for the input and output of the CBC files can be found in the folder source array_io of the companion CD ROM Geometry and Boundary Conditions Extension Type Description XY ASCII sizes and numbers of cells and layers BOT CBC Elevation of the bottom of layers IBD CBC IBOUND matrix used by MODFLOW and MOC3D TIC CBC ICBUND matrix used by MT3D and MT3DMS TOP CBC Elevation of the top of layers BOZ ZONE Elevation of the bottom of layers IBZ ZONE IBOUND matrix TOZ ZONE Elevation of the top of layers Initial Values Extension Type Description HEA CBC Initial hydraulic heads TSC CBC Initial concentration used by MT3D and MOCSD 201 230 CBC Initial concentration of species 1 to 30 used by MT3DMS HEZ ZONE Initial hydraulic heads MT1 ZONE _ Initial concentration 301 330 ZONE Initial concentration of species 1 to 30 used by MT3DMS Aquifer Parameters Extension Type Description CON CBC horizontal hydraulic conductivity HIC CBC Transmissivity LEA CBC Vertical hydraulic conductivity LKN CBC Vertical leakance POR
41. Source of the CD ROM Setting Up PMWIN You install PMWIN on your computer using the self installing program PM32010 EXE contained in the folder programs pm5 of the CD ROM Please note If you are using Windows NT 4 0 you must install the Service Pack 3 or above before installing PMWIN Refer to the file readme txt on the PM5 CD ROM for more information Documentation The folder Document of the CD ROM contains electronic documents in the Portable Document Format PDF You must first install the Acrobat Reader before you can read or print the PDF documents You can find the installation file of the Acrobat Reader in the folder Reader Execute the file Reader win95 ar302 exe from the CD directly and follow the screen to install the Reader Starting PMWIN Once you have completed the installation procedure you can start Processing Modflow by using the Start button on the task bar in Windows Introduction Processing Modflow 5 Online Help The online help system references nearly all aspects of PMWIN You can access Help through the Help menu Contents command by searching for specific topics with the Help Search tool or by clicking the Help button to get context sensitive Help Help Search The fastest way to find a particular topic in Help is to use the Search dialog box To display the Search dialog box either choose Search from the Help menu or click the Search button on any Help topic screen gt To search He
42. The water table is 10 m at the upstream side of the dam and 2 m at the downstream side The material of the dam 15 homogeneous and isotropic with a hydraulic conductivity of 1 x 10 m s The unrealistic bank slope is used here to simplify the data input Your task 1s to calculate the seepage surface and the seepage rate by using a vertical cross sectional numerical model Compare the seepage rate with an analytical solution after Dupuit impervious 10 Fig 6 49 Seepage surface through a dam Modeling Approach and Simulation Results To compute the head distribution and the seepage surface it is sufficient to consider a vertical cross section of the aquifer with a uniform thickness of 1 m The aquifer is simulated using a grid of one layer 21 columns and 20 rows A regular grid spacing of 0 5 m is used for each column The layer type is 0 confined The boundary at the upstream side of the dam is modeled as fixed head boundary with the hydraulic head h 10 m On the right hand side of the dam there are four fixed head cells with h 2 2 m The other cells on this boundary are modelled as drain cells with a high drain hydraulic conductance L T value The elevation of the drain is set the same as the bottom elevation of each cell for example the 2 0 m for the cell 21 16 1 and 2 5 m for the cell 21 15 1 The drain cells are activated only if water table is higher than the level of the 6 5 3 Seepage Surface through a Dam
43. Transmissivity varies Confined Calculated Calculated Fig 3 14 The Layer Options dialog box gt Transmissivity MODFLOW requires transmissivity horizontal hydraulic conductivity x layer thickness L for layers of type 0 or 2 If the Transmissivity flag is set to Calculated PMWIN calculates transmissivity by using user specified horizontal hydraulic conductivity and the elevations of the top and bottom of each layer Set the Transmissivity flag to User Specified if you want to specify transmissivity manually gt Leakance For flow simulations involving more than one model layer MODFLOW requires the input of the vertical conductance term known as vertical leakance VCONT between two model layers Set the Leakance flag of a layer to User Specified if you want to specify the vertical leakance between the layer and the underlaying layer directly In the Data Editor the vertical leakance between the layers i and i 1 is given as the data of the layer 1 A VCONT array is not required for the bottom layer because MODFLOW assumes that the botton layer is underlain by impermeable material Setting the Leakance flag of a layer to Calculated causes PMWIN to calculate VCONT by using the following rule As illustrated in Fig 3 15a when each model layer represents a different hydrostratigraphic unit or when two or more model layers represent a single hydrostratigraphic unit PMWIN uses eq 3 1 to calculate the verti
44. Water Resour Res 13 1 125 136 Watson D F 1992 Contouring A guide to the analysis and display of spatial data with programs on diskette Pergamon ISBN 0 08 040286 0 Wexler E J 1992 Analytical solutions for one two and three dimensional solute transport in groundwater systems with uniform flow U S Geological Survey Techniques of Water Resources Investigations Book 3 Chapter B7 190 pp Wilson J L and P J Miller 1978 Two dimensional plume in uniform ground water flow J Hyd Div ASCE 4 503 514 Zheng C 1990 MT3D a modular three dimensional transport model S S Papadopulos amp Associates Inc Rockville Maryland Zheng C 1993 Extension of the method of characteristics for simulation of solute transport in three dimensions Ground Water 31 3 456 465 Zheng C and G D Bennett 1995 Applied contaminant transport modeling Theory and parctice 440 pp Van Nostrand Reinhold New York 8 References 334 Processing Modflow Zheng C 1996 MT3D Version DoD 1 5 a modular three dimensional transport model The Hydrogeology Group University of Alabama Zheng C and P P Wang 1995 MT3DMS A modular three dimensional multispecies transport model for simulation of advection dispersion and chemical reactions of contaminants in groundwater systems Documentation and user s guide Departments of Geology and Mathematics University of Alabama 8 References
45. by using the Maps Options dialog box See section 3 9 for details gt Save and Load The entries in the Trace Table can be saved or loaded in trace files The format of the trace file is given in Appendix 2 3 8 The Value Menu Processing Modflow Search And Modify Parameter Digitizer Active Color Minimum 1 Display Only 165 Sa eee Display Only Display Only Display Only Display Only Display Only Display Only Display Only Display Only Display Only Display Only Display Only Display Only Display Only Display Only pjocjejojmimpjeojojojo DI Ooo oo oo oo oo oo oloo sey ny Maps Load o Cancel Help Fig 3 61 The Search and Modify dialog box Result Extractor Y ou may use this menu item to call the Result Extractor Refer to Chapter 5 for details about the use of this modeling tool Boreholes and Observations You may use this menu item to open the Boreholes and Observations dialog box Refer to section 3 5 for details about this dialog box 3 9 The Options menu There are four menu items in the Options menu namely Environment Maps Display Mode and Input Method The use of the menu items Environment and Maps is described below Refer to section 3 2 for the description of the display modes and input methods
46. conceal from PEST the true value of a parameter as seen by the model PEST optimizing instead the parameter b where O S 3 51 3 6 5 PEST Inverse Modeling 144 Processing Modflow Here b is the parameter optimized by PEST b is the parameter seen by the model while S and O are the scale and offset values for that parameter respectively If you wish to leave a parameter unaffected by scale and offset enter the SCALE as 1 0 and the OFFSET as 0 0 List of Calibration Parameters PEST x Parameters Group Definitions Prior Information Control Data Options PARVALI PARLBND PARUBND 1 i Transmissivity in layer 3 0 00001 0 ce ololololololololololololololo ololololololololololololololo Fig 3 53 The List of Calibration Parameters PEST dialog box gt Group Definitions In PEST the input variables that define how derivatives are calculated pertain to parameter eroups rather than to individual parameters These input variables are spcified 1n the Group Definitions tab of the List of Calibration Parameters PEST dialog box Thus derivative data does not need to be entered individually for each parameter however if you wish you can define a group for every parameter and set the derivative variables for each parameter separately In many cases pa
47. g is simulated by assigning an initial concentration of 5 g m to the cell 10 1 1 Using the Boreholes and Observations dialog box an observation borehole is set in the center of the cell 30 1 1 The breakthrough curves for the dispersivities of 1 m and 4 m are shown in Fig 6 58 It 15 interesting to see that the concentration peak arrives earlier with a lower concentration value when the value of dispersivity 1s higher At the first glance this result is somewhat confusing because the center of mass should travel with the same velocity regardless of the value of dispersivity Because of a higher dispersivity the front of the concentration plume travels faster and at the same time the intensity of the concentration drops faster This combination causes this phenomenon Analytical solutions for solute transport involving advection dispersion and first order 6 6 1 One Dimensional Dispersive Transport 296 Processing Modflow irreversible decay in a steady state uniform flow field are available in many text books for example Javandel et al 1984 Kinzelbach 1986 or Sun 1995 A computer program for the analytical solutions of 1 D and 2 D solute transport for point like pollutant injections 1s provided by Rausch 1998 and included in the folder Source analytical solution of the companion CD ROM This program is written in BASIC and can be run by the BASIC interpreter QBASIC under MS DOS Try to use this program to compare the
48. if the selected simulation result does not exist 5 4 The Results Extractor Processing Modflow 209 MT3DMS The primary result of MT3DMS is concentration The species number and simulation time from which the result is read can be selected from the Species Number and Total Elapsed Time drop down boxes These drop down boxes are empty if simulation results do not exist Save and Read To extract a certain result type simply click the Read button You may save the contents of the spreadsheet by clicking the Save button and specifying the file name and the file type in a Save Matrix As dialog box There are four file types ASCH Matrix Warp form ASCII Matrix SURFER files and SURFER files real world An ASCII Matrix file may be loaded into the spreadsheet at a later time The format of the ASCII matrix file is described in Appendix 2 A SURFER file has three columns containing the x y coordinates and the value of each cell If the file type is SURFER files the origin of the coordinate system for saving the file is set at the lower left corner of the model grid If the file type is SURFER files real world the real world coordinates of each cell will be saved The real world coordinate system is defined by Options Environment section 3 9 Apply The Apply button appears only if you start the Result Extractor from the Data Editor via Value Result Extractor Click on this button the content of the spreadsheet will
49. improved efficiency the user can apply MOC3D to a subgrid of the primary MODFLOW that is used to solve the flow equation However the transport subgrid must have uniform grid spacing along rows and columns Using MODFLOW as a built in function MOC3D can be modified to simulate density driven flow and transport The purpose of PEST and UCODE 1s to assist in data interpretation and in model calibration If there are field or laboratory measurements PEST and UCODE can adjust model parameters and or excitation data 1n order that the discrepancies between the pertinent model generated numbers and the corresponding measurements are reduced to a minimum Both codes do this by taking control of the model MODFLOW and running it as many times as is necessary in order to determine this optimal set of parameters and or excitations Introduction 4 Processing Modflow System Requirements Hardware Personal computer running Microsoft Windows 95 98 or Windows NT 4 0 or above 16 MB of available memory 32MB or more highly recommended A CD ROM drive and a hard disk VGA or higher resolution monitor Microsoft Mouse or compatible pointing device Software A FORTRAN compiler is required if you intend to modify and compile the models MODFLOW 88 MODFLOW 96 MOC3D MT3D or MT3DMS For the reason of compability the models must be compiled by a Lahey Fortran compiler The source codes of the above mentioned models are saved in the folder
50. of the Data Editor Chemical reactions supported by MT3DMS include equilibrium controlled sorption non equilibrium sorption and first order irreversible rate reactions such as radioactive decay or biodegradation The equilibrium controlled sorption and first order irreversible rate reactions are essentially the same as in MT3D see MT3D Chemical Reaction Layer by Layer It should be noted that the basic chemical reaction supported by the present version of MT3DMS is intended for single species systems More sophisticated reaction models such as RT3D Clement 1997 TBC Schafer et al 1997 should be used for multi species reactions Three new options the first order kinetic sorption and the dual domain mass transfer with 3 6 4 MT3DMS Processing Modflow 135 or without sorption are described below Using these options you have the choice of specifying the initial concentration for the sorbed or immobile phase for each species To do this simple check Use the initial concentration for the nonequibrilium sorbed or immobile liquid phase and specify the concentration value to Initial concentration for the sorbed phase or Initial concentration for the immobile liquid phase in the Chemical Reaction MT3DMS dialog box Chemical Reaction MT3DMS x Type of Sorption First order kinetic sorption nonequilibrium Simulate the radioactive decay or biodegradation Use the initial concentration for the non
51. pmSdata samplel oc dat Well c pmbdata samplel wel dat weltpl dat Recharge c pmbdata samplel rch dat rchtpl dat gg Solver PCG2 c pmbdata samplel pcq2 dat Options Regenerate all input files for MODFLOW and PEST Generate input files only don t start PEST Perform PESTCHEK prior to running PEST Check the model data Cancel Help Fig 2 38 The Run PEST dialog box Check calibration results During the automatic calibration several result files are created PEST writes the optimized parameter values to the input files of MODFLOW BCF DAT WEL DAT etc and creates a detailed run record file path PESTCTL REC where path is the folder in which your model data are saved The simulation results of MODFLOW are updated by using the optimized parameter values which are saved in a separate file PESTCTL PAR 2 3 1 Perform Automatic Calibration with PEST 48 Processing Modflow Note that PMWIN does not retrieve the optimized parameter values into the data matrices Your PMWIN model data will not be modified in any way This provides more security for the model data because an automatic calibration process does not necessarily lead to a success If you want to operate on a calibrated model you can import the model by choosing Convert Model from the File menu see Chapter 3 for details You can create a scatter diagram to present the calibration result The observed head values are plotte
52. select the option These data will be printed or saved every Nth particle moves and enter N 20 Click OK to accept all other default values and close the Output Control MOC3D dialog box Fig 2 32 2 2 2 Perform Transport Simulation with MOC3D 42 Processing Modflow C These data will be printed or saved Jat the end of every stress period These data will be printed or saved every Nth particle moves Cancel Help Fig 2 32 The Output Control MOC3D dialog box gt To perform the transport simulation 1 Choose MOC3D Run from the Models menu The Run MOC3D dialog box appears Fig 2 33 2 Click OK to start the transport computation Prior to running MOC3D PMWIN will use user specified data to generate input files for MOC3D as listed in the table of the Run MOC3D dialog box An input file will be generated only if the generate flag is set to El You can click on the button to toggle the generate flag between and Ll Generally you do not need to change the flags as PMWIN will care about the settings Run Moc3d x Moc3d Program c program files pm5 moc3d moc3d exe 3 Basic Package c pmbdata samplel bas dat Block Centered Flow lc pm5data samplel Abcef dat Output Control c pmbdata samplel oc dat Vell c pmbdata sample wel dat Recharge c pmbdata samplel rch dat Solver PCG2 c pmSdata samplel pcg2 dat MOC3D Main Package c pm5data samplel imocmain dat MOC3D concentration in recha
53. water level h 5m A Cross section Fig 6 43 Problem description 6 5 1 Inflow of Water into an Excavation Pit Processing Modflow 283 Modeling Approach and Simulation Results The aquifer is simulated using a grid of one layer 40 columns and 19 rows A regular grid spacing of 50 m is used for each column and row The layer type is 1 unconfined To simplify the simulation use of symmetry is made by modeling only half the domain The river and the pit are modelled as fixed head boundaries with hydraulic heads of h 5 m and 3 m respectively All other boundaries are no flow boundaries The distance between the eastern no flow boundary and the pit is not known a priori and must be selected large enough so that it is not influenced by the pit Fig 6 44 shows the head contours the catchment area of the excavation and two cross sections Using the Water budget calculator the inflow into the pit 1s calculated at 2 x 0 0129 m s 0 0258 m s cross section Fig 6 44 Simulated head distribution and catchment area of the excavation pit 6 5 1 Inflow of Water into an Excavation Pit 284 Processing Modflow 6 5 2 Flow Net and Seepage under a Weir Folder pm5 examples geotechniques geo2 Overview of the Problem This example is adopted from Kinzelbach and Rausc
54. 1192811E 05 IN 0000000 00 0000000 00 6035380E 04 96962 768 035 0000000 00 0000000 00 4005010E 04 IN 0000000 00 0000000 00 5766129E 04 4027577 04 0000000 00 0000000 00 1979371E 03 OUT 0000000800 0000000 00 0000000 00 0000000 00 9696278E 05 0000000E 10 0000000 00 0000000 00 9696380E 05 OUT 0000000E 00 0000000 00 0000000 00 0000000 00 4027577 04 0000000E 10 4027589E 04 OUT 0000000 00 0000000 00 0000000 00 0000000 00 0000000 00 2000001E 03 200000 1LE D 2 IN OUT 0000000E 00 0000000 00 7992809E 05 0000000 00 9696278E 05 0000000E 10 0000000 00 1999998E 06 4964317E 06 IN OUT 0000000 00 0000000 00 6035380E 04 9696278E 05 4027577E 04 0000000E 10 22040 152E 07 IN OUT 0 0000000ET00 0 0000000 00 B 6 0 1 5766129E 04 4027577 04 0000000 00 2000001E 03 0629959E 06 Step 6 Produce Output In addition to the water budget PMWIN provides various possibilities for checking simulation 2 1 Run a Steady State Flow Simulation Processing Modflow 23 results and creating graphical outputs Pathlines and velocity vectors can be displayed by PMPATH Using the Results Extractor simulation results of any layer and time step can be read from the unformatted binary re
55. 1988 was designed to account for the amount of flow in streams and to simulate the interaction between surface streams and groundwater The particle tracking model PMPATH uses a semi analytical particle tracking scheme Pollock 1988 to calculate the groundwater paths and travel times PMPATH allows a user to perform particle tracking with just a few clicks of the mouse Both forward and backward particle tracking schemes are allowed for steady state and transient flow fields PMPATH calculates and displays pathlines or flowlines and travel time marks simultaneously It provides various on screen graphical options including head contours drawdown contours and velocity vectors The MT3D transport model uses a mixed Eulerian Lagrangian approach to the solution of the three dimensional advective dispersive reactive transport equation MT3D is based on the assumption that changes in the concentration field will not affect the flow field significantly This 1 Introduction Processing Modflow 3 allows the user to construct and calibrate a flow model independently After a flow simulation is complete MT3D simulates solute transport by using the calculated hydraulic heads and various flow terms saved by MODFLOW MT3D can be used to simulate changes in concentration of single species miscible contaminants in groundwater considering advection dispersion and some simple chemical reactions The chemical reactions included in the model are limited to equi
56. 3 20 3 17 Fig 6 51 Calculated hydraulic heads after one iteration step b 4b5 b 43 5 38 6 30 6 19 6 05 5 00 5 5 5 41 5 05 ae 4 33 3 94 3 60 3 39 3 13 2 00 eb 2 6 2 59 5 43 6 40 6 35 be 6 16 6 02 5 03 5 61 5 33 4 97 4 50 4 00 3 50 3 00 3 00 2 2 0 2 0 2 0 2 0 O Gy MIO 00 0 IO ce M Fig 6 52 Calculated hydraulic heads distribution and the form of the seepage surface elevation of the cell bottom m Processing Modflow 280 6 5 4 Cutoff Wall Folder pm5 examples geotechniques geo4 Overview of the Problem As shown in Fig 6 53 a highly contaminated area is located in the first stratigraphic unit of an unconfined aquifer To the west and east of the aquifer exist fixed head boundaries with the hydraulic head h 0 4 m and 0 5 m The aquifer consists of five stratigraphic units Each unit is horizontally isotropic with uniform thickness The elevations and horizontal hydraulic conductivities are illustrated in Fig 6 53 The vertical hydraulic conductivities are assumed to be a tenth of the horizontal hydraulic conductivities The effective porosity of the aquifer is 0 15 The recharge rate is 1 x 10 m s Because of the high cost the contaminants cannot be removed Your task is to develop a strategy to isolate the contamination There are four steps to be done 1 Construct a groundwater flow model and perform a steady state flow simulation by using
57. 3 34 Refer to MOC3D Dispersion amp Chemical Reaction for more about the molecular diffusion coefficient and dispersivity In MT3D the concentration change due to dispersion alone is solved with a fully explicit central finite difference scheme There is a certain stability criterion associated with this scheme To retain stability the transport step size cannot exceed an upper limit defined by eq 3 38 0 5 R Dy Dy 3 38 Ay Az At lt 3 6 3 MT3D Processing Modflow 125 where Ax Ay and Az are the widths of the cell in the x y and z directions H is the retardation factor The components of the hydrodynamic dispersion coefficient D Dy and D are calculated by eq 3 39 2 2 2 V V Da 0 T Qn Ary D lV lV lV 2 2 2 V V V 4 1X Z D Q v m D 3 39 ge Z X io d 0 OQ Quy Oy v 14 lV where ot L is the longitudinal dispersivity o4 L is the horizontal transverse dispersivity L is the vertical transverse dispersivity V Vy LT are components of the flow velocity vector along the x y and z axes and M vy vi 3 40 Eq 3 38 is calculated for each active cell and the minimum At is taken as the maximum allowed step size for solving the dispersion term This criterion is compared with other transport step size constraints to determine the minimum step size for the simulation Ge
58. 32 bit compiler Fortunately PESTLM is sufficient for most groundwater problems You should use PESTLM unless you have other problems with the conventional memory gt File Table PMWIN uses the user specified data to generate input files of MODFLOW and PEST Description gives the name of the packages used in the flow model The path and name of the input file are shown in Destination File PMWIN generates an input file only if the corresponding Generate flag is checked You may click on a flag to check or uncheck it Normally you do not need to worry about these flags as PMWIN will care about the settings gt Options Regenerate all input files for MODFLOW and PEST You should check this option if the input files have been deleted or overwritten by other programs Generate input files only don t start PEST Check this option if you do not want to run PEST You can start the simulation at a later time by executing the batch file PEST BAT Perform PESTCHEK prior to running PEST PESTCHEK reads the PEST input files 3 6 5 PEST Inverse Modeling Processing Modflow 153 generated by PMWIN making sure that every item 1s consistent with every other item and writes errors to the file PEST CHK It is recommended to use PESTCHEK as PMWIN and PEST do not carry out consistency checks of all user specified control data and parameters Check the model data Before creating data files for MODFLOW PMWIN will check the geometr
59. Environment The Environment Options dialog box allows you to configure the coordinate system and modify appearance of the model grid Available settings are grouped under three tabs Appearance 3 9 The Options Menu 166 Processing Modflow Coordinate System and Contours The checkbox Display zones in the cell by cell mode is used to force PMWIN to display the user specified zones in the cell by cell input mode gt Appearance Fig 3 62 allows you to change the visibility and appearance color of each simulated component A simulated component is visible if the corresponding Visibility checkbox is checked To select a new color click on the colored cell a button appears then click on the button and select a color from a Color dialog box Environment Options LX Appearance Coordinate System Contours E Grid Inactive cell Fixed head cell IBOUND lt 0 Fixed concentration cell ICBUND lt 0 General boundary head cell Discharge well Recharge well Drain Hiver or stream Horizontal flow barrier slurny wall Digitized point _ Time variant specified head Time variant specified concentration Cancel Help Fig 3 62 The Appearance tab of the Environment Options dialog box gt Coordinate System is used to define the extent and location of the area of interest the worksheet and to define location and orientation of the model grid As il
60. Geological Survey Water Supply Paper 1536 J 343 366 Davis J C 1973 Statistics and data analysis in geology John Wiley amp Sons Inc Doherty J 1990 MODINV Suite of software for MODFLOW pre processing post processing and parameter optimization User s manual Australian Centre for Tropical Freshwater Research Doherty J L Brebber and P Whyte 1994 PEST Model independent parameter estimation User s manual Watermark Computing Australia Domenico P A 1972 Concepts and Models in Groundwater Hydrology McGraw Hill N Y AOS p Domenico P A and Schwartz F W 1990 Physical and Chemical Hydrogeology John Wiley amp Sons New York 709 pp Englund E and A Sparks 1991 User s guide of GEO EAS Geostatistical environmental assessment software EPA 600 8 91 008 Fenske J P S A Leake and D E Prudic 1996 Documentation of a computer program RES1 to simulate leakage from reservoirs using the modular finite difference ground water flow model MODFLOW U S Geological Survey Open File Report 96 364 Fetter C W 1994 Applied Hydrogeology 3rd Edition Macmillan College New York 691 pp 8 References Processing Modflow 329 Franke R 1982 Scattered data interpolation Tests of some methods Mathematics of computation 38 157 181 200 Freeze R A and J A Cherry 1979 Groundwater Prentice Hall Inc Englewood Cliffs New Jersey Frenzel H 1995 A field generator based
61. If the simulation time limit is reached and this option is not checked PMPATH calculates flowlines by assuming that the flow field of the first or last time step 1s steady state gt Pathline Colors Normally the color of each pathline is the same as the color of each particle It is sometimes useful when the colors of pathlines are distinguished by layers instead of particles There are two ways to change the color of each layer 1 Change the color individually a Click on a colored cell of the table a J button will appear in the cell b Click on the button then select a color from a Color dialog box 2 Change the color using the Color Spectrum dialog box Using the Color Spectrum dialog box the color of each layer can be automatically assigned so you get a gradational change from one color to another a Click the header button Color A Color Spectrum dialog box appears b Inthe Color Spectrum dialog box click the Minimum Color button to display a Color dialog box In the Color dialog box select a color and click OK Repeat this procedure for the Maximum Color button c Inthe Color Spectrum dialog box click OK A gradation of colors from the minimum to the maximum is assigned to each layer gt RCH EVT Options Recharge The option is disabled if recharge 1s not used MODFLOW treats recharge as an internal distributed source of a cell and does not assign it to any of the six cell faces The distributed sour
62. Mode PMPATH can be used to calculate flowlines or pathlines Flowlines indicate the instantaneous direction of flow throughout a system at all times of a steady state flow simulation or at a given time step of a transient flow simulation Pathlines map the route that an individual particle of water follows through a region of flow during a steady state or transient condition In a steady state flow system pathlines will coincide with flowlines In this case only the option Flowline use the flow field from the current time step is available In the case of a transient flow simulation that groundwater flow varies from time step to time step the flowlines and pathlines do not coincide Use the option Pathlines use transient flow fields to calculate transient pathlines Stop Conditions In general particles will stop when the allowed travel time defined in Tracking Step is reached or when the particles reach specified head cells In addition to these conditions two stop conditions are available 1 Particles stop when they enter cells with internal sinks The flow model MODFLOW includes the options to simulate wells drains rivers general head boundaries streams evapotranspiration and recharge Except the last two options they are treated as internal distributed sources or sinks by PMPATH If the internal sink of a cell is sufficiently strong flow will be into the cell from all cell faces In that case every particle that enters the cell wi
63. Model PMPATH PMPATH is an advective transport model running independently from PMWIN PMPATH retrieves the groundwater models and simulation result from PMWIN and MODFLOW A semi analytical particle tracking scheme Pollock 1988 1989 1s used to calculate the groundwater paths and travel times Through the interactive graphical modeling environment of PMPATH you can place particles and perform particle tracking with just a few mouse clicks While most available particle tracking models need postprocessors for visualization of computed paths and times data PMPATH calculates and animates the pathlines simultaneously Fig 4 1 Moreover PMPATH provides various on screen graphical options including head contours drawdown contours and velocity vectors for any selected model layer and time step Both forward and backward particle tracking are allowed for steady state and transient flow simulations For transient flow simulations particles can start from the beginning of any time step During the simulation the particle tracking algorithm will check the current time of every particle If a particle reaches the end forward tracking or the beginning backward tracking of a time step PMPATH forces the particle to wait until the flow field of the next time step has been read The particle tracking simulation proceeds until all particles have left the model via sinks or until the user specified time limit is reached wW PMPATH example pm5 loa
64. Modeling Environment Processing Modflow 187 small Click the Stop button if the particle tracking simulation appears too slow Run particles forward step by step Click this button to move particles forward a single particle tracking step The particle tracking step length is defined in the Particle Tracking Time Properties dialog box See sec 4 3 for details Run particles forward Click this button to execute forward particle tracking for a specified time length The time length is the product of the number of particle tracking steps and the particle tracking step length given in the Particle Tracking Time Properties dialog box See sec 4 3 for details 4 3 PMPATH Options Menu Environment The Environment Options dialog box Fig 4 7 allows to modify the appearance of the model The available settings are grouped under 4 tabs namely Appearance Cross Sections Velocity vectors and Contours These tabs are described below Appearance allows to change the visibility and appearance color of each simulated component A simulated component is visible if the corresponding Visibility check box is checked To select a new color click on the colored cell a zl button appears then click on the button and select a color from a Color dialog box gt Cross Sections To display the cross section windows check the Visible check box To display the model grid check the Show grid check box To display the groundwater su
65. NCOL NROW 2 Data MATRIX NCOL NROW Explanation of Fields Used in Input Instructions ALL DATA IN THE SAME RECORD ARE SEPARATED BY A COMMA OR BLANK NCOL is the number of model columns NROW is the number of model rows MATRIX is a two dimensional data matrix saved row by row Matrix can be saved in free format If the wrap from is used to save the matrix each line of the matrix contains up to 20 values Example If NCOL 6 and NROW 5 an ASCII Matrix file would be 6 5 121 152 133 144 315 516 221 252 233 244 215 216 321 352 333 344 315 316 421 452 483 444 415 416 521 552 533 544 515 516 Or 6 5 121 152 133 144 315 516 221 252 233 244 215 216 321 352 333 344 315 316 421 452 433 444 415 416 921 552 533 544 515 516 Boreholes file A borehole file can be saved or loaded by the Boreholes and Observations dialog box see section 3 5 File Format 1 Data LABEL 2 Data NB XXX XXX XXX XXX The following data repeats NB times 3 Data ACTIVE X Y LAYER DRAW COLOR NAME Explanation of Fields Used in Input Instructions ALL DATA IN THE SAME RECORD ARE SEPARATED BY A COMMA OR BLANK LABEL is the file label It must be PMWIN5000 BOR FILE NB is the number of boreholes Maximum number of NB is 1000 XXX reserved ACTIVE A borehole is active if Active 1 X is the x coordinate of the borehole Y is the y coordinate of the borehole LAYER is the layer number of the borehole DRAW If DRAW 1 the obervation vs time curve of a b
66. Press any key to exit the DOS Window Produce output Using the Presentation tool and the Results Extractor you can create contour plots for the water level at the end of each time step The water level at the end of the pumping period dry season corresponds to the heads in time step 12 of period 1 Fig 6 5 The water level at the end of the recharge period wet season corresponds to the heads in time step 6 of period 2 Fig 6 6 Both figures use the contour interval of 0 5m The minumum and maximum contour levels are 12 5m and 19m respectively Animation Now we can create an animation sequence to show the development of the water level during the wet and dry seasons gt create an animation sequence 1 Before creating an animation sequence open the Enivironment Option dialog box to make sure that the contours are set to visible and the contour levels are set properly 2 Select File Animation 3 Inthe Animation dialog box click the open file button a A Save File dialog box appears Select or specify a base filename for the animation files in the dialog box then click Open Note that you cannot save the animation files in the same folder as your model data So you need first to create a new folder or select another folder for the files 4 Check Create New Frames set Result Type to Hydraulic Head and set Display Time s to 0 2 Like a movie an animation sequence is based on lots of frames Each frame 1s save
67. Solver PCG 2 c program files pm5 examples samplel pcqe2 q Options Regenerate all input files for MODFLOW and PEST Generate input files only don t start PEST Perform PESTCHEK prior to running PEST Check the model data Cancel Help Fig 3 54 The Run PEST dialog box 3 6 5 PEST Inverse Modeling 154 Processing Modflow 3 6 6 UCODE Inverse Modeling This menu provides an interface between PMWIN the flow model MODFLOW and the inverse model UCODE The use of this interface 1s very similar to that of PEST The adjustable parameters and or excitations are given in Table 3 7 During a calibration process UCODE searches for a parameter set for which the sum of squared deviations between model calculated and measurement values at the observation boreholes is reduced to a minimum The coordinates of the observation boreholes and measurement values are given in Parameters Boreholes and Observations A simultaneous fit of highly correlated parameters for example transmissivities and recharge for given head observations 15 of little value in steady state problems due to the non uniqueness of such a fit gt define an estimated parameter 1 From the Parameters or Models Modflow menu select a parameter or a package for example Horizontal Hydraulic Conductivity or Well 2 Assignaunique parameter number to cells within an area where the parameter value will be estimated If yo
68. Solver Help Interval IPRSOR 1 Acceleration Parameter ACCL 1 Convergence Criterion Head Change L 01 Fig 3 32 The Slice Successive Overrelaxation Package dialog box MODFLOW Run Select this menu item if you want to check the model data or run the flow simulation with MODFLOW The available settings of the Run Modflow dialog box Fig 3 33 are described below gt Modflow Version and Modflow Program Several variants of MODFLOW are included in PMWIN all of them are compiled with a FORTRAN compiler of Lahey PMWIN automatically installs the executables of these variants Their full paths and file names are given in table 3 4 If you want to use a compiled version located in another position click the open file button and select the desired code from a dialog box The User s own version must be selected if you want to use your own version of MODFLOW Refer to Appendix 5 for how to configure PMWIN to run with your own MODFLOW gt File Table PMWIN uses the user specified data to generate input files for MODFLOW 3 6 MODFLOW Processing Modflow 109 and MODPATH Description gives the name of the packages used in the flow model The path and name of the input file are shown in Destination File PMWIN generates an input file only if the corresponding Generate flag is checked You may click on a flag to check or uncheck it Normally you do not need to wor
69. Specification File The grid specification file provides the grid geometry and location details File Format 1 Data NROW NCOL 2 Data X Y ANGLE 3 Data DELR NCOL 4 Data DELC NROW 5 Date X1 Y1 6 Data X2 Y2 7 Data NLAY Explanation of Fields Used in Input Instructions NROW is the number of model rows NCOL is the number of model columns X is the x coordinate of the top left corner of the model grid is the y coordinate of the top left corner of the model grid ANGLE is the rotation angle expressed in degrees and measured countercolckwise from the positive x axis DELR is the cell width along rows Read one value for each of the NCOL columns This is a single array with one value for each column DELC is the cell width along columns Read one value for each of the NROW rows This is a single array with one value for each row X1 Y1 is the coordinates of the lower left corner of the model worksheet see Coordinate System for details Appendix 2 Files and Formats 312 Processing Modflow X2 Y2 is the coordinates of the upper right corner of the model worksheet see Coordinate System for details NLAY is the number of model layers Line Map file A line map file contains a series of polylines each polyline is defined by the number of vertices and a series of coordinate pairs File Format Repeat Data 1 and 2 for each polyline 1 Data NVERTEX The following data repeats NVERTEX times 2 Data
70. The configuration of the model is shown in Fig 6 59 The model layer is simulated as a confined layer The top and bottom of the model layer are at an elevation of 10 m and 0 m respectively To simulate the groundwater seepage velocity of 1 3 m day fixed head boundaries with h 11 m and h 10 m are assigned to the west and east side of the model The horizontal hydraulic conductivity 15 45 m day The flow field was first calculcated by MODFLOW The third order TVD scheme was used in the simulation for the advection term and the GCG solver is used to solve the system equations The contour map of the concentration field at the end of the 365 day simulation period obtained for this example is shown in Fig 6 60 An analytical solution for this problem is given by Wilson and Miller 1978 The analytical solution is applicable only under the assumption that 1 the aquifer 1s relatively thin so that instantaneous vertical mixing can be assumed 2 the injection rate 1s insignificant compared with the ambient uniform flow Fig 6 61 shows the breakthrough curves at an observation well located 60 m downstream of the injection well The analytical solution 1s obtained by using the computer program Rausch 6 6 2 Two Dimensional Transport in a Uniform Flow Field 208 Processing Modflow 1998 included in the folder Source analytical solution of the companion CD ROM Fig 6 62 compares the analytical solution with the numerical solution obtained by
71. The next step is to specify the type of layers gt assign the type of layers 1 Choose Layer Type from the Grid menu A Layer Options dialog box appears 2 1 Run a Steady State Flow Simulation 12 Processing Modflow 2 Clickacell of the Type column a drop down button will appear within the cell By clicking the drop down button a list containing the avaliable layer types Fig 2 5 will be displayed 3 Select 1 Unconfined for the first layer and 0 Confined for the other layers then click OK to close the dialog box As transmissivity and leakance are by default assumed to be calculated see Fig 2 5 from conductivities and geometrical properties the primary input variables to be specified are horizontal and vertical hydraulic conductivities Now you must specify basic boundary conditions of the flow model The basic boundary contition array IBOUND array contains a code for each model cell which indicates whether 1 the hydraulic head 15 computed active variable head cell or active cell 2 the hydraulic head is kept fixed at a given value fixed head cell or time varying specified head cell or 3 no flow takes place within the cell inactive cell Use 1 for an active cell 1 for a constant head cell and 0 for an inactive cell For the sample problem we need to assign 1 to the cells on the west and east boundaries and 1 to all other cells gt assign the boundary condition to the flow model 1 Choo
72. Time Variant Specified 20 20 20 Head Dey LL 1 This version of MODFLOW uses dynamic memory allocation and allows pratically unlimited number of cells 2 DE45is not supported by the KIWA version of MODFLOW 3 The Density Package is a proprietary software and is contained only in the KIWA version of MODFLOW Use of this software is royalty free The source code is however not contained in PMWIN Appendix 5 Using PMWIN with your MODFLOW Processing Modflow 325 Table 7 2 IUNIT assignments given in the main program of MODFLOW IF IUNIT 1 GT 0 CALL BCF2AL ISUM LENX LCSC1 LCHY 1 LCBOT LCTOP LCSC2 LCTRPY IUNIT 1 ISS 2 NCOL NROW NLAY IOUT IBCFCB LCWETD IWDFLG LCCVWD 3 WETFCT IWETIT IHDWET HDRY IF IUNIT 2 GT 0 CALL WEL1AL ISUM LENX LCWELL MXWELL NWELLS 1 IUNIT 2 IOUT IWELCB IF IUNIT 3 GT 0 CALL DRN1AL ISUM LENX LCDRAI NDRAIN MXDRN 1 IUNIT 3 OUT IDRNCB IF IUNIT 4 GT 0 CALL RIV1AL ISUM LENX LCRIVR MXRIVR NRIVER 1 IUNIT 4 IOUT IRIVCB IF IUNIT 5b GT 0 CALL EVT1AL ISUM LENX LCIEVT LCEVTR LCEXDP 1 LCSURF NCOL NROW NEVTOP IUNIT 5 IOUT IEVTCB IF IUNIT 7 GT 0 CALL GHB1AL ISUM LENX LCBNDS NBOUND MXBND 1 IUNIT 7 OUT IGHBCB IF IUNIT 8 GT 0 CALL RCH1AL ISUM LENX LCIRCH LCRECH NRCHOP 1 NCOL NROW IUNIT 8 IOUT IRCHCB IF IUNIT 9 GT 0 CALL SIP1AL ISUM LENX LCEL LCFL LCGL LCV 1 LCHDCG LCLRCH LCW MXITER NPARM NCOL NROW NLAY 2 IUNIT 9 IOUT IF IUNIT 11 GT 0 CALL SOR1AL ISUM LENX LCA LCRES LC
73. Unconfined Aquifer System with River Processing Modflow 243 Fig 6 13 125 years streamlines particles are started at the cell 6 5 1 and flow towards Well 2 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River 244 Processing Modflow 6 2 Basic Flow Problems 6 2 1 Determination of Catchment Areas Folder pm5 examples basic Woasic1 Overview of the Problem Fig 6 14 shows a part of an unconfined aquifer The extent of the aquifer to the North and South is assumed to be unlimited The aquifer is homogeneous and isotropic with a measured horizontal hydraulic conductivity of 0 0005 m s and an effective porosity of 0 1 The elevations of the aquifer top and bottom are 15 m and m respectively The aquifer is bounded by a no flow zone to the west To the east exists a river which is in direct hydraulic connection with the aquifer and can be treated as fixed head boundary The river width is 50 m and stage is 10m The mean groundwater recharge rate is 8 x 10 m s A pumping well is located at a distance of 1000 m from the river Your task is to calculate the catchment area of the well and the 365 days capture zone under steady state flow conditions Well Q 005 m s 1475 m 1000 m No flow boundary fixed head boundary 2525 m ME M Fig 6 14 Plan view of the model area 6 2 1 Determination of Catchment Areas Processing Modflow 245 Modeling Approach and Simula
74. X Axis Time Y Axis Data Types Min time Min value Iv Save Plot As fo fo Observation Data gt gt Max time Max value EU pe Up IRR Draw horizontal grid MER Ticks Draw vertical grid __ i Auto Adjust Min Max Close Fig 5 8 The Graph Viewer displaying drawdown time curves Fig 5 9 Interpolation of simulation results to a user specified borehole The available settings of the Graph Viewer are summarized below The Borehole table The table contains the borehole numbers and the plot colors The curve of a borehole will be displayed only when the corresponding Plot flag is checked The plot color of each curve is given in the Color column Click on a colored cell of the table to 5 6 The Graph Viewer 212 Processing Modflow change the color Note that if you have deactivated a borehole in the Boreholes and Observations dialog box the corresponding row of the table is dimmed and its settings cannot be changed Time Min Time and Max Time define a range of simulation time for which the curves should be displayed The number of desired ticks is given in the edit field Ticks Y Axis Min Value and Max Value specify the minimum Y axis value and maximum Y axis value on the graph The number of desired ticks 1s given in the edit field Ticks Data Types Check the Calculated or Observation box to display the curves based on the co
75. again dispersion sink source and reaction terms are solved implicitly without any stability constraints The required settings and parameters for this package are specified in the Generalized Conjugate Gradient GCG dialog box Fig 3 51 3 6 4 MT3DMS 138 Processing Modflow Generalized Conjugate Gradient GCG Preconditioning Method Modified Incomplete Cholesky Max Number of Outer Iterations MT TER iu Max Number af Inner Iterations TERT Relaxation Factor Concentration Closure Criterion Concentration Change Printout Interval LEN Include full dispersion tensor memory intensive rem Fig 3 51 The Generalized Conjugate Gradient GCG dialog box Preconditioning Method The GCG package has three preconditioning options Jacobi Symmetric Successive Overrelaxation SSOR and the Modified Incomplete Cholesky MIC The MIC preconditioner usually takes fewer iterations than the other methods but it requires significantly more memory Max Number of Outer Iterations MXITER and Max Number of Inner Iterations ITER1 The GCG solver has two iteration loops an inner loop and an outer loop Like the PCG2 solver of MODFLOW see MODFLOW gt Solvers gt PCG2 within the inner loop all coefficients in the transport matrix A and the right hand side vector b remain unchanged during inner iterations The inner loop continues until ITER iterations are executed or the convergenc
76. allow you to run several models simultaneously multitasking 2 Click OK PMWIN takes a few seconds to create the new model The name of the new model name is shown in the title bar Step 2 Assign Model Data The second step in running a flow simulation is to generate the model grid mesh specify boundary conditions and assign model parameters to the model grid PMWIN requires the use of consistent units throughout the modeling process For example if you are using length L units of meters and time T units of seconds hydraulic conductivity will be expressed in units of m s pumping rates will be in units of m s and dispersivities will be in units of In MODFLOW an aquifer system is replaced by a discretized domain consisting of an array of nodes and associated finite difference blocks cells Fig 2 2 shows a spatial discretization of an aquifer system with a mesh of cells and nodes at which hydraulic heads are calculated The nodal grid forms the framework of the numerical model Hydrostratigraphic units can be represented by one or more model layers The thicknesses of each model cell and the width of each column and row may be variable The locations of cells are described in terms of columns rows and layers PMWIN uses an index notation J I K for locating the cells For example the cell located in the 2nd column 6th row and the first layer 1s denoted by 2 6 1 gt generate the model grid 1 Choose
77. amp 3 2 x P6 stat 2 2 flag 2 plot 1 gt Control Data The control data are used to control the sensitivity and regression calculations and define the inversion algorithm The items of the control data Fig 3 56 are described below Convergence criterion TOL When parameter values change less than this fractional amount between regression iterations parameter estimation converges 0 01 15 recommended Convergence criterion SOSR When the sum of squared weighted residuals changes less than this fractional amount over three regression iterations parameter estimation converges Ideally for the final results convergence is achieved by satisfying the TOL criterion so that SOSR can be equal to 0 0 in which case SOSR is not used as a convergence criteria Values of SOSR of 0 01 and even 0 1 can be useful however in the early stages of model calibration because it stops the regression when it 1s not progressing Maximum number of regression iterations MA X ITER is self explanatory Starting with twice the number of parameters is recommended Maximum fractional parameter change MAX CHANGE is the maximum fractional change of a parameter value allowed in one regression iteration For example if MAX CHANGE 2 0 a parameter value of 1 0 will not be allowed to change by more than 2 0 MAX CHANGE times the parameter value Consequently the new value will be between 1 0 and 3 0 A parameter value of 2 0 will not be allowed to change
78. appears Fig 2 38 2 Click OK to start the calibration Prior to running PEST PMWIN will use user specified data to generate input files for PEST and MODFLOW as listed in the table of the Run PEST dialog box An input file will be generated only if the generate flag is set to EJ You can click on the button to toggle the generate flag between and Ll Generally you do not need to change the flags as PMWIN will care about the settings 2 3 Perform Automatic Calibration with PEST Processing Modflow 47 List of Calibration Parameters PEST EG Parameters Group Definitions Prior Information Control Data Options PARVALI PARLEND PARUBND iTransmissivityinlayer3 0 00001 0 oo oo OO wi oj B amp B oo ro 4 4 4 an ce oie eoo 4 1 oo oo oo oo Fig 2 37 The List of Calibration Parameters PEST dialog box Run PEST Modflow Version MODFLOW96 INTERFACE TO MT3D96 AND LATER Modflow Program c program files pm5 modflw96 lkmt2 modflow2 exe PEST Program c program filles pm5 pest pestlite exe Generate Description Destination File Basic Package c pmbdata samplel bas dat Block Centered Flow BCF1 2 c pmbdeta samplel bct dat bcttpl dat Output Control c
79. are specified in the Slice Successive Overrelaxation Package dialog box Fig 3 32 The parameters are described below gt MXITER is the maximum number of iterations in one time step in an attempt to solve the system of finite difference equations gt IPRSOR is the printout interval for SSOR A positive integer is required The maximum head change positive or negative is saved in the run record file OUTPUT DAT for each iteration of a time step whenever the time step is an even multiple of IPRSOR This printout also occurs at the end of each stress period regardless of the value of IPRSOR gt ACCL is the acceleration parameter usually between 1 0 and 2 0 gt Head Change is the head change criterion for convergence When the maximum absolute value of head change from all cells during an iteration 1s less than or equal to Head Change iteration stops 3 6 1 MODFLOW 108 Processing Modflow Strongly Implicit Procedure Package x Allowed Iteration Number MXITER 50 Printout From the Solver Interval IPRSIP 1 No of Iteration Parameters NPARM 5 Acceleration Parameter 3 Convergence Criterion Head Change L 01 Fig 3 31 The Strongly Implicit Procedure Package dialog box OK Cancel Help dii Slice Successive Overrelaxation Package Allowed Iteration Number 50 Cancel Printout From the
80. around each front Away from such fronts the advection term is solved by MMOC The criterion for controlling the switch between the and MMCC schemes is given by DCHMOC see below Because of the problems of numerical dispersion and artificial oscillation the upstream finite difference method 1s only suitable for solving transport problems not dominated by advection When the grid Peclet number Pe Ax a Ax is the grid spacing and Q is the longitudinal dispersivity 15 smaller than two the upstream finite difference method 15 reasonably accurate It is advisable to use the upstream finite difference method anyway for obtaining first approximations in the initial stages of a modeling study gt Particle Tracking Algorithm MT3D provides three particle tracking options a first order Euler algorithm a fourth order Runge Kutta algorithm and a combination of these two Using the first order Euler algorithm numerical errors tend to be large unless small transport steps are used The allowed transport step At of a particle is determined by MT3D using eq 3 36 Ax Ay Az VOV V lt y R MIN 3 36 where Ax Ay and Az are the cell widths in the x y and z directions y is the Courant number The particle velocities v V and v at X y Z are obtained by linear interpolation from the specific discharges at the cell faces The minimum At of all particles is used in a transport step The basic idea of
81. as name of the new model 3 Click OK to exit the dialog box Step 2 Define Model Size gt To define the size of the model Select Grid Mesh Size 2 Inthe Model Dimension dialog box enter Layers Number 3 Columns Number 27 Size 250 Rows Number 20 Size 250 3 Click OK to exit this dialog box You are now in the Grid Editor of the PMWIN To help visualize the problem we can overlay a DXF file as a map which gives us the locations of the boundaries and the pumping wells gt To load a map 1 Select Options Maps to open the Map Options dialog box 2 Click the box beside the space for the DXF filename to activate that particular map it 1s also possible to choose a color by clicking on the colored square 3 In the first filename field of DXF files click the right mouse button to bring up Map Files dialog box 4 Choose BASEMAP2 DXF from the folder pm5 examples tutorials tutorial2 click OK to exit the dialog box 5 Click OK to exit the Map Options dialog box You will see that it does not match the grid that you have generated gt move the grid Select Options Environment to open the Environment Options dialog box 2 Enter X 200 and Y 6000 and click OK to exit the dialog box 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River 234 Processing Modflow 3 Leave the Data Editor by File Leave Editor Yes Step 3 Refine Model Grid gt Torefine the mod
82. at the cell throughout the simulation A fixed head cell may or may not be a constant concentration cell The initial concentration is specified by choosing MT3D Initial Concentration or MT3DMS Initial Concentration from the Models menu Note that for multi species simulation in MT3DMS the boundary condition type defined by ICBUND is shared by all species Top of Layers TOP The top elevation of a layer 1s required when 1 layer type 2 or 3 is used 2 one of the transport models PMPATH MT3D MT3DMS or MOC3D is used 3 vertical leakance to the underlaying layer is calculated by PMWIN or 4 transmissivity or confined storage coefficient 15 calculated by PMWIN see Layer Type Bottom of Layers BOT The bottom elevation of a layer 1s required when 1 layer type 1 or 3 is used 2 one of the transport models PMPATH MT3D MT3DMS or MOC3D is used 3 vertical leakance to the underlaying layer is calculated by PMWIN or 4 transmissivity or confined storage coefficient is calculated by PMWIN see Layer Type 3 4 The Grid Menu 74 Processing Modflow 3 5 The Parameters Menu Time Use the Time Parameters dialog box Fig 3 16 to specify temporal parameters including the time unit the length of stress periods and the numbers of stress periods time steps and transport steps The table and the elements of this dialog box are described below Multiplier Transpart ha 12 365 365 365 1
83. be put into the model grid Note that this button is dimmed and cannot be used if the spreadsheet is empty or the orientation is not Plan View or the data has been applied to the model grid Results Extractor E MODFLOW MT3DMs Result Type Hydraulic Head Stress Period Time Step Orientation Plan View Layer ColumnWicdth 27 11 12 13 14 15 16 17 REN 13 36 13 36 13 36 13 36 13 36 13 36 13 37604 13 37470 13 37384 13 37314 13 37261 13 3722 13 M Baal 13 361 13 36066 13 3803 13 38012 13 37991 13 37973 13 4 13 3813 13 382183 13 3824 13 38273 13 36296 13 36316 13 5 13 37943 13 36024 13 38103 13 38178 13 382493 13 3831 13 amp 13 37382 13 37506 13 37626 13 37746 13 37661 13 37973 13 13 36496 13 36662 13 36823 13 369581 13 37134 13 3728 1 ig 13 3573 13 35922 13 36091 13 36261 13 36453 13 36619 13 9 13 35401 13 35615 13 35614 13 36005 13 36219 13 36415 1 30 13 3509 13 35304 13 35541 13 35759 13 35976 13 36187 13 13 34793 13 35026 13 35263 13 35492 13 35716 13 35941 13 32 13 34485 13 34729 13 34971 13 35209 13 35445 13 35679 1i 13 13 34164 13 34416 13 34665 13 34912 13 35156 13 354 13 12 2720721 13 3 4n0n 12724244 13 34Cn0 13 34A0C14 d ohio idi b Save Read Help Close ek ee 1 co oo ds co 2 4 Fig 5 7 The Results Extractor dialog box 5 4 The Results Extractor
84. be specified you may try to run your model by selecting the menu item Run from the corresponding model in the Models menu PMWIN will then tell you what parameters or model data are necessary to run your model if unspecified An overview of the menus in PMWIN is given in table 3 1 Most of the user specified data are saved in binary files A list of the internal data files of PMWIN is given in Appendix 4 Prior to running the supported models MODFLOW MT3D MT3DMS MOC3D or the inverse models PEST and UCODE PMWIN will generate the required ASCII input files The names of the ASCII input files are given in Appendix 3 The formats of the input files of MODFLOW and MT3D MT3DMS and MOC3D can be found in the user s guide the corresponding software on the companion CD ROM The particle tracking model PMPATH retrieves the binary data files of PMWIN directly thus no ASCII input file 1s required by PMPATH 3 The Modeling Environment 54 Processing Modflow Table 3 1 An overview of the menus in PMWIN Menu Description File Create new models open existing models convert models to the PMWIN format Save and print plots Grid Generate or modify the size of a model grid input of the geometry of the aquifer Parameters Input of spatial aquifer parameters for example transmissivity Input of temporal parameters for example simulation length or number of stress periods Models opecify model specific data using the module provided and call
85. be used throughout the first three periods The data of the fourth period will be used for the rest of the simulation The data of the third period will not be used because the Use flag 15 cleared 3 2 The Data Editor 64 Processing Modflow Temporal Data E a lu Fig 3 9 The Temporal Data dialog box 3 2 The Data Editor Processing Modflow 65 3 3 The File Menu New Model Select New Model to create a new model A New Model dialog box allows you to specify a filename on any available folder or drive for the new model A PMWIN model must always have the file extension pm where is the version number of Processing Modflow All file names valid under Windows 95 98 NT with up to 120 characters can be used It is a good idea to save every model in a separate folder where the model and its output data will be kept This will also allow you to run several models simultaneously multitasking Open Model Use Open Model to load an existing PMWIN model Once a model is opened PMWIN displays the filename of the model on the title bar Convert Model A Convert Models dialog box appears after selecting this menu item The options in this dialog box are grouped under three tabs PMWIN 4 x MODFLOW 88 96 and Telescoping Flow Model Fig 3 10 Using the first two tabs you can convert existing PMWIN 4 x or MODFLOW models to the format of the present version of PMWIN The use of these two tabs is straigh
86. columns 31 rows and 1 layer is used to simulate the concentration change at the injection extration well numerical results were compared with the approximate analytical solution of Gelhar and Collins 1971 PM5 TRANSPORT5 This model is described in section 7 7 of the manual of 5 A numerical model consisting of 21 columns 15 rows and 8 layers is used to solve three dimensional transport in a uniform flow field The point source was simulated at column 3 row 8 and layer 7 Numerical results were compared with the analytical solution of Hunt 1978 PM5 TRANSPORT6 This model is described in section 7 9 of the manual of MT3DMS This example illustrates the application of MODFLOW MT3D MT3DMS to a problem involving transport of contaminants in a two dimensional heterogeneous aquifer 6 6 3 Benchmark Problems and Application Examples from Literature Processing Modflow 301 Table 6 7 continued PMB TRANSPORT7 This model is described in section 7 10 of the manual of MT3DMS This example illustrates the application of MT3D MT3DMS to an actual field problem involving the evaluation of the effectiveness of proposed groundwater remediation schemes PM5 TRANSPORT8 This model is described in the section MODEL TESTING AND EVALUATION One Dimensional Steady Flow of the user s guide of MOCS3D A numerical model consisting of 122 columns 1 row and 1 layer is used to simulate one dimensional transport having a third t
87. completed MODFLOW saves the simulation results in various unformatted binary files as listed in Table 2 1 Prior to running MODFLOW the user may control the output of these unformatted binary files by choosing Modflow Output Control from the Models menu The output file path INTERBED DAT will only be generated if the Interbed Storage Package 1s activated see Chapter 3 for details about the Interbed Storage Package 2 Run a Steady State Flow Simulation 18 Processing Modflow To check the quality of the simulation results MODFLOW calculates a volumetric water budget for the entire model at the end of each time step and saves it in the file output dat see Table 2 2 A water budget provides an indication of the overall acceptability of the numerical solution In numerical solution techniques the system of equations solved by a model actually consists of a flow continuity statement for each model cell Continuity should also exist for the total flows into and out of the entire model or a sub region This means that the difference between total inflow and total outflow should equal to steady state flow simulation or to the total change in storage transient flow simulation It is recommended to check the record file or at least take a glance at 1t The record file contains other further essential information In case of difficulties this supplementary information could be very helpful T Run Modflow Ld Run Modflow Modf
88. drag a zoom window over a part of the model Zoom Out Forces PMPATH to display the entire model grid Particle color Allows a user to select a color for new particles from a color dialog box Run particles backward executes backward particle tracking for a time lenght The time length is defined by the product of the number of particle tracking steps and the particle tracking step length Run particles backward step by step executes backward particle tracking for a user specified particle tracking step length Stop stops the particle tracking or stops drawing particles Run particles forward step by step executes backward particle tracking for a user specified particle tracking step length Tai A Run particles forward executes forward particle tracking for a time length The time length is defined by the product of the number of particle tracking steps and the particle tracking step length Open model Opens an existing model created by PMWIN A PMWIN model file always has the extension PMS Prior to openning a model the flow simulation must be performed By default PMPATH reads the unformatted binary files HEADS DAT and BUDGET DAT from the same folder as the loaded model Set particle Use the following two methods to place particles in the current layer The current layer is shown in the tool bar Fig 4 5 Change it first if you need to place particles into another layer Note that particles can
89. elevation of the base of the aquifer to Om Although the default value in this model is zero we still have to enter the editor to let the model knows that 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge 2 Processing Modflow the parameter has been specified Wall z Well a a Well 5 Well m n Wall 7 Wall H Well 8 H E a Fig 6 3 Boundary conditions Aquifer parameters The next stage is to assign the aquifer parameters gt specify the horizontal hydraulic conductivity Select Parameters Horizontal Hydraulic Conductivity 2 Since the horizontal hydraulic conductivity is uniform throughout the model it is possible to set a single value to the entire grid by Value gt Reset Matrix 3 Enter 160 in the Reset Matrix dialog box and click OK to exit Leave the Data Editor by File Leave Editor gt Yes 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge Processing Modflow 223 Initial Conditions MODFLOW requires some initial hydraulic head conditions to enable it to perform the flow simulation In a steady state flow model only the hydraulic head values of the fixed head cells are important as these do not change throughout the simulation The values in the other cekks serve as initial guesses for the iterative solvers In a transient simulation however the hydraulic heads at the start of the simulation are the basis for determining the resulting head distribution after the aquifer is su
90. end of each time step and saves the results in the simulation record file OUTPUT DAT A water budget provides an indication of the overall acceptability of the numerical solution In numerical solution techniques the system of equations solved by a model actually consists of a flow continuity statement for each model cell Continuity should therefore also exist for the total flows into and out of the entire model or a sub region This means that the difference between total inflow and total outflow should equal the total change in storage It 1s recommended to read the record file The record file also contains other essential information In case of difficulties this supplementary information could be very helpful 3 6 1 MODFLOW 102 Processing Modflow MODFLOW Solvers To calculate heads in each cell in the finite difference grid MODFLOW prepares one finite difference equation for each cell expressing the relationship between the head at a node and the heads at each of the six adjacent nodes at the end of a time step Because each equation may involve up to seven unknown values of head and because the set of unknown head values changes from one equation to the next through the grid the equations for the entire grid must be solved simultaneously at each time step The system of simultaneous finite difference linear equations can be expressed in matrix notation as Ax b 3 30 where A is a coefficient matrix assembled by MODFLOW using u
91. fit the observation values as closely as possible That 1s PEST searches a parameter set for which the sum of squared deviations between model calculated and measurement values at the observation boreholes 15 reduced to a minimum The coordinates of the observation boreholes and measurement values are given in Parameters Boreholes and Observations A simultaneous fit of highly correlated parameters for example transmissivities and recharge is of little value in steady state problems due to the non uniqueness of such a fit gt define an estimated parameter 1 From the Parameters or Models Modflow menu select a parameter or a package for example Horizontal Hydraulic Conductivity or Well 2 Assignaunique parameter number to cells within an area where the parameter value will be estimated If you intend to calibrate the pumping rate of wells or the conductance of head dependent cells e g drain general head boundary river or stream cells for example you must also assign a non zero pumping rate or conductance to those cells Pumping rate or conductance values will not be adjusted 1f the user specifed values are equal to zero 3 Use the List of Calibration Parameters PEST dialog box to activate the estimated parameter and to specify the necessary values 3 6 5 PEST Inverse Modeling Processing Modflow 141 Note that for layers of type 0 confined and 2 confined unconfined transmissivity const MODFLOW reads transmis
92. gt MODFLOW Well 2 Ateach of the wells marked by a little shaded box on the DXF Map click the left mouse button to select the cell and then the right mouse button to set the pumping rate to 3888 in the Cell Value dialog box This pumping rate is equivalent to 45 I s the negative sign means that water 1s being extracted from the system A recharge well would have a positive sign 3 Exit the Data Editor by File Leave Editor Upon leaving you are presented with a Temporal Data dialog box this allows you to select and edit the data so that different values can apply during different Stress Periods 4 Select Period 2 and click on Edit Data The status bar displays Period 2 indicating that you are entering data for stress period 2 5 For each well in the system set the pumping rate to O this is the default value 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge Processing Modflow 220 6 Exit the Data Editor by File Leave Editor which again brings up the Temporal Data dialog box 7 Exit the Temporal Data dialog box and the Data Editor by Leave Editor gt Yes Recharge rates There are two recharge periods namely the dry season when recharge is zero and the wet season when recharge is 7 5 x 10 m day v To specify the recharge rate Select Models gt MODFLOW gt Recharge Edit Set the entire grid to a uniform value for the first Stress Period by Value Reset Matrix M za In the Reset Matrix di
93. h a Exponential model Vin 1 EXP h a 5 2 5 3 5 4 5 5 5 6 Where C is the variance of measurement data and will automatically be calculated by the program the correlation length the nugget variance amp the slope and w the power factor of the power model W 1 yields the linear model Fig 5 4 The variance C will be calculated by the program a ariogram Ea Yariogram Model Power or Linear Parameters Correlation Length Nugget Variance Col Power Factor wi slope Fig 5 3 The Variogram dialog box 5 2 The Field Interpolator Processing Modflow 205 Yh Yh 084 linear 0 8 logarithmic 0 6 0 6 0 4 C 0 4 d OWer 0 2 02 1 2 3 4 h 2 5 102030 Fig 5 4 Linear power and logarithmic model Search Method The interpolation algorithms use three search methods to find a certain number of the measurement data points to interpolate a cell value The search methods are called SIMPLE QUADRANT and OCTANT The search radius is assumed to be infinitely large The SIMPLE search method finds the data points nearest to the model cell The QUADRANT or OCTANT search methods find closest data points from each quadrant or octant around a model cell Fig 5 5a and 5 5b The number of data points used in a search is defined by the Data Per Sector value If fewer than Data Per Sector points are found in a sector the program uses the other nearest poi
94. into the volume of the solid portion V and the volume of viods the porosity n is defined as n2 V V Effective porosity with the respect to flow through the medium is normally smaller than porosity because part of the fluid in the pore space is immobile or partially immobile This may occur when the flow takes place in a fine textured medium where adhesion 1 e the attraction to the solid surface of the porous matrix by the fluid molecules adjacent to it is 1mportant On a more macroscopic scale the effective porosity also has to accommodate the fact that unresolved conductivity variations lead to a reduction of effective porosity Effective porosity 1s used by transport models for example PMPATH MOC3D or MT3D to calculate the average velocity of the flow through the porous medium If a dual porosity system is simulated by MT3DMS effective porosity should be specified as the portion of total porosity filled with mobile water and the immobile porosity is defined through MT3DMS Chemical Reaction of the Models menu A summary of representive porosity values for different soil types can be found in Zheng and Bennett 1995 or Domenico and Schwartz 1990 Specific Storage Storage Coefficient and Specific Yield For transient flow simulations MODFLOW requires dimensionless storage terms specified for each layer of the model For a steady state simulation these menu items are not used and are therefore dimmed 3 5 The Parameters M
95. ions in porous geologic materials The diffusion coefficients D of the major ions Na Mg Ca HCO SO are temperature dependent and range from 1x 10 to 2x 10 m s at 25 C Li and Gregory 1974 Robinson and Stokes 1965 At 5 C the coefficients are about 50 smaller The molecular diffusion coefficient 1s 3 6 2 MOC3D Processing Modflow 115 generally very small and negligible compared to the mechanical dispersion see below and is only important when groundwater velocity is very low gt Longitudinal dispersivity ot L horizontal transverse dispersivity L and vertical transverse dispersivity L describe the spreading of the solute concentration in groundwater caused by the irregular shape of the interconnected pore space and the velocity variations at the microscopic level The velocity of groundwater varies according to the size of the pores and water moves faster at the internal points between soil grains than on the solid surface This spreading 1s often referred to as mechnical dispersion and it occurs in all three spatial directions The coefficient of mechanical dispersion is defined by Q vi where Q is the dispersivity and V is the average linear velocity in the direction The sum of mechanical dispersion and molecular diffusion is called hydrodynamic dispersion Values of dispersivity used for simulations generally depend on the scale of a concentration plume being considere
96. is the folder in which PMWIN is installed If you want to use another version of Moc3d click the open file button E and select the desired program from a dialog box gt File Table PMWIN uses the user specified data to generate input files of MODFLOW and MOC3D Description gives the name of the packages used in the flow model The path and name of the input file are shown in Destination File PMWIN generates an input file only if the Generate flag is checked You may click on a flag to check or uncheck it Generally you do not need to worry about these flags as PMWIN will take care of the settings gt Options Regenerate all input files You should check this option if the input files have been deleted or overwritten by other programs Check the model data Before creating data files for MODFLOW PMWIN will check the geometry of the model and the consistency of the model data given in table 3 5 if this option is checked The errors if any are saved in the file CHECK LST located in the same folder as your model data Generate input files only don t start MOC3D Check this option if you do not want to run MOC3D You can start the simulation at a later time by executing the batch file MOC3D BAT 3 6 2 MOC3D Processing Modflow 119 gt Click OK to start the generation of input files for MODFLOW and MOC3D In addition PMWIN generates a batch file MOC3D BAT saved in your model folder When all necessary files are generated
97. layer is acceptably small This means the model equations have been correctly solved To calculate the exact flow rates to the well we repeat the previous procedure for calculating subregional water budgets This time we only assign the cell 25 15 1 to zone 1 the cell 25 15 2 to zone 2 and the cell 25 15 3 to zone 3 All other cells are assigned to zone 0 The water budget is shown in Table 2 4 The pumping well is extracting 7 7992809E 05 m s from the first layer 5 603538E 04 m s from the second layer and 5 5766129E 04 m s from the third layer Almost all water withdrawn comes from the second stratigraphic unit as can be expected from the configuration of the aquifer Table 2 4 Output from the Water Budget Calculator for the pumping well FLOWS ARE CONSIDERED IN IF THEY THE UNIT THE FLOWS IS L 3 T ARE ENTERING A SUBREGION TIME STEP 1 OF STRESS PERIOD ZONE 1 LAYER 1 FLOW TERM STORAGE CONSTANT HEAD HORIZ EXCHANGE EXCHANGE UPPER EXCHANGE LOWER WELLS DRAINS RECHARGE SUM OF THE LAYER ZONE 2 FLOW TERM STORAGE CONSTANT HEAD HORIZ EXCHANGE EXCHANGE UPPER EXCHANGE LOWER WELLS SUM OF THE LAYER ZONE FLOW TERM STORAGE CONSTANT HEAD HORIZ EXCHANGE EXCHANGE UPPER EXCHANGE LOWER WELLS SUM OF THE LAYER LAYER 3 LAYER IN 0000000 00 0000000 00 7992809E 05 0000000 00 0000000 00 0000000 00 0000000 00 1999998E 06
98. may not be imported into PMWIN without modifying the scale factor and the X Y values If these values are incorrect a DXF map will be displayed too small too large or outside the worksheet If this happens use the Environment options dialog box to define a very large worksheet ensuring that the map can be displayed within the worksheet Then you can check the units on the imported map by moving the mouse around the map and looking at the X and Y coordinates displayed in the status bar Choose two points that are a known distance apart and check their distance with the status bar If the distance 1s incorrect compute a scale factor and import the map again Once you have the correct scale factor you may shift the scaled DXF map to the desired position by using X and Y Fig 3 70 uses a triangle as an example to show the use of X Y and the scale factor 3 9 The Options Menu 172 Processing Modflow s Xat X S Y4 Y X5 Y3 X4 Y4 X2 Y2 s X4 X sS Y Y s X X s Yo Y a triangle before scaling and shifting the triangle after scaling and shifting a scale factor s and displacements X and Y are used Fig 3 70 Scaling a vector graphic gt Raster Graphics Raster graphics saved in Windows Bitmap bmp or JPEG jpg format can be imported and geo referenced gt import a raster graphic 1 Click the Raster Graphics tab 2 Click the open file button and select a file from a Raster Graphics dialog
99. of water movement at any instant of a given time step of the simulation The time step is defined by Current Time of the Particle Tracking Time Properties dialog box see Fig 4 11 Check the Visible check box the projection of velocity vectors of each active model cell will be displayed on the Worksheet and cross section windows Click the color button next to the Visible check box to change the appearance color of the velocity vectors The appearance size of the largest velocity vector is defined by the Vector size in pixels which defaults to 25 and can be ranged from 1 to 32767 Environment Options Fixed head cell JIBOUND U Fixed concentration cell ICBUND D General boundary head cell Discharge well Recharge well Drain Hiver or stream Horizontal flow barrier slurry wall Reservoir Time variant specified head Fig 4 7 The Environment Options dialog box 4 3 PMPATH Options Menu Processing Modflow 189 Contours PMPATH displays contours based on the calculated heads or drawdowns The Contours tab allows you to control the display of the contour levels labels and colors The options of this tab are listed below Visible Contours are visible if this box is checked Orient label uphill If this box is checked the contours labels are displayed so that they are always oriented uphill 1 e oriented to places with higher cell values Head or Drawdown Use
100. often around 0 01 If it is set too large the criterion for moving on to the next optimization iteration is too easily met and PEST is not given the opportunity of adjusting lambda to its optimal value for that particular stage of the parameter estimation process On the other hand if PHIREDLAM is set too low PEST will test too many Marquardt lambdas too many parameter sets on each iteration step when it would be better off starting a new iteration NUMLAM is the maximum number of lambdas parameter sets that PEST can test during any one optimization iteration It should normally be set between 5 and 10 For cases where parameters are being adjusted near their upper or lower limits and for which some parameters are consequently being frozen thus reducing the dimension of the problem in parameter space experience has shown that a value closer to 10 may be more appropriate than one closer to 5 RELPARMAX and FACPARMAX are used to limit parameter adjustments RELPARMAX is the maximum relative change that a parameter is allowed to undergo between iterations whereas FACPARMAX is the maximum factor change that a parameter is allowed to undergo A parameter is denoted as either relative limited or factor limited through PARCHGLIM see p 142 3 6 5 PEST Inverse Modeling Processing Modflow 149 If a parameter b is relative limited The relative change between optimization iterations 1 1 and 1 1s defined as b bj D The absolute v
101. only when FORCEN is Always 3 or Switch PEST provides three vaiants Parabolic Best fit or Outside pts Refer to the manual of PEST for details about these methods Prior Information It often happens that we have some information concerning the parameters that we wish to optimize and that we obtained this information independently of the current experiment This information may be in the form of other unrelated estimates of some or all of the parameters or of relationships between parameters It is often useful to include this information in the parameter estimation process because it may lend stability to the process To define a prior information first check the Active flag in the Prior Information tab then enter the prior information equation in the Prior Information column The syntax of a prior information equation is PIFAC PARNME PIFAC log PARNME PIVAL WEIGHT 3 52 To the left of the sign there are one or more combinations of a factor PIFAC plus parameter name PARNME with a log prefix to the parameter name if appropriate PIFAC and PARNME are separated by a character which must be separated from PIFAC and PARNME by at least one space signifying multiplication All parameters referenced in a prior information equation must be adjustable parameters 1 e you must not include any fixed or tied parameters in a prior information equation Furthermore any particular parameter can be referenced only once i
102. output During a transport simulation MT3D writes a detailed run record to the file pathNOUTPUT MT3 where path is the folder in which your model data are saved MT3D saves the simulation results in various files which can be controlled by choosing MT3D Output Control from the Models menu To check the quality of the simulation results a mass budget is calculated at the end of each transport step and accumulated to provide summarized information on the total mass into or out of the groundwater flow system The discrepancy between the total mass in and out servers as an indicator of the accuracy of the simulation results It is highly recommended to check the record file or at least take a glance at it Using Presentation you can generate contour maps of the calculated concentration Fig 2 27 shows the calculated concentration in the third layer at the end of the simulation simulation time 9 467E 07 seconds To generate the breakthrough curves choose Graphs Concentration Time MT3D from the Tools menu Click on the Plot flags of the Boreholes table until they are set to Fig 2 28 2 2 1 Perform Transport Simulation with MT3D 38 Processing Modflow Processing Modflow SAMPLE1 PM5 File Value Options Help no flow boundary contaminated constant head boundary h 9 m constant head boundary h 8 m no flow boundary 515 7567 4642746 25 153 Steady state ecycle
103. package The simulation 6 2 6 Simulation of an Aquifer System with irregular Recharge and a Stream 262 Processing Modflow was done to determine if the STR1 package correctly accumulates flow from the aquifer into the stream Annual recharge is 1 5 feet recharge for analytical solution Ss recharge rate assigned to each 15 day period in model simulation Recharge rate in hundreths of a foot per day DON RRA AMA a 7 f Af I A 2 120 180 240 300 360 Time in days since start of infiltration period Fig 6 27 Distribution of recharge used for analytical solution and the model simulation after Prudic 1988 simulation results E Z analytical solution eene imm om pm omes ponens dise ep Eee pes e i i i i i hand Se a a ooo ooo ooo omo oo il rA l l 2 i p Tor ar aao CU Xe 1 a Ni UE NE EE 4 MEN en e E i 1 i 1 U a i 1 i i i E Foo i aa a pepe 2 ae a I E a I I I L 9 i On 2 XOT u O crm 4 n a p EE TUE ORI ese a Gece ages CRINE n MUT eq es Se ee ee ee ME ed c 5 2 9 5 4E 1 1 56E 6 1 67E 6 Elapsed simulation time seconds Fig 6 28 Comparison of simulation results to analytical solution developed by Oakes and Wilkinson
104. path of the particle within the cell The particle tracking sequence is repeated until the particle reaches a discharge point or until a user specified time limit is reached Backward particle tracking is implemented by multiplying 4 1 The Semi analytical Particle Tracking Method Processing Modflow 179 all velocity terms in equations 4 3a 4 3f by 1 For transient flow fields in addition to the condition for steady state flow fields t and t must lie within the same time step In PMPATH each particle may be associated with a set of attributes 1 e the retardation factor the starting forward and backward travel times and positions If a particle 1s travelling across the end forward tracking or the beginning backward tracking of a time step of a flow simulation PMPATH sets t to the end or beginning time of this time step and forces the particle to wait until the flow field of the next time step forward tracking or the previous time step backward tracking 1s read If the end or beginning time of a transient flow simulation 1s reached the most recent flow field can be treated as steady state and the movement of particles can go on Consideration of the display of the calculated pathlines Because of the capability of calculating particle s exit point from a cell directly pathlines displayed by PMPATH may sometimes intersect each other Consider the case shown in Fig 4 4 two particles within a two dimensional cell start at th
105. polyline is defined by a header line and a series of coordinate pairs The header line only contains the number of the coordinate pairs Refer to Appendix 2 for the format of the Line Map files gt To import a DXF map or a Line map 1 Select the Vector Graphics tab 2 Click the right mouse button on any of the DXF File or Line Map File edit fields and select a file from a Map Files dialog box 3 9 The Options Menu Processing Modflow 171 3 f necessary use a scale factor to enlarge or reduce the appearance size of the map Then use the values in X and Y to shift the scaled map to the desired position For details see Scaling a vector graphic below 4 Click the colored button in the front of the edit field and select a color for the DXF map from a Color dialog box The color will be assigned to a DXF graphics entity if the entity s color is not defined in the DXF file A line map will always use the selected color 5 Check the check box next to the edit field The map will be displayed only when the box is checked Maps Options Ea Vector Graphics Raster Graphics DXF File Filename Line Map File Filename X Y Factor Fig 3 69 The Maps Options dialog box gt Scaling a vector graphic X and Y should be and Scale should be 1 if a DXF file is generated by PMWIN or PMPATH Because of different length units DXF files created by some drawing or CAD software
106. simulation programs For example you can add wells use the recharge or river modules to MODFLOW or define the advection or dispersion parameters in MT3D The simulation programs are called by selecting Run from the corresponding model Tools Call the modeling tools Value Manipulate model data read or save model data in separate files Options Modify the appearance of the model grid on the screen Load site maps Help Call the Help file 3 The Modeling Environment Processing Modflow 35 3 1 The Grid Editor The first steps in the groundwater modeling process are to define the goals of the model select a computer code here MODFLOW collect the necessary data develop a conceptual model of the groundwater system and define the spatial discretization of the model domain Anderson and Woessner 1992 discuss the steps in going from aquifer systems to a numerical model grid Zheng and Bennett 1995 describe the design of model grids which are intended for use both in flow and transport simulations These sources provide valuable general information relating to spatial discretization and grid design in numerical groundwater modeling In the block centered finite difference method an aquifer system is replaced by a discretized domain consisting of an array of nodes and associated finite difference blocks cells Fig 3 1 shows a spatial discretization of an aquifer system with a mesh of cells and nodes at which hydraulic heads are cal
107. stress preconsolidation stress compaction is permanent inelastic In analogy to eq 3 10 the package uses the following equation to calculate the approximate inelastic compaction b L Ab Ah Sq by Ah S 3 11 where S L is the skeletal component of inelastic specific storage and S is the user specified inelastic storage factor Elastic compaction or expansion of sediments in an unconfined aquifer can be expressed as Ab Ah 1 n n Se b Ah 5S 3 12 ske where n is porosity and n is moisture content above water table as a fraction of total volumn of porous medium Similarly inelastic compaction or expansion of sediments can be expressed as Ab Ah 1 n n 5 skv Ah S 3 13 For an aquifer with n interbeds with specific storage values S 9 5 and with thicknesses b Dn a single equivalent storage factor Sytem is given by Jorgenson 1980 S S D 5 D S b 3 14 system sn n 3 6 1 MODFLOW Processing Modflow 87 MODFLOW Recharge The Recharge package is designed to simulate areally distributed recharge to the groundwater system Recharge is defined by assigning the following data to each vertical column of cells in the Recharge Package dialog box Fig 3 20 of the Data Editor Recharge Flux I LT Layer Indicator lac Parameter Number After specifying the values they are displayed from left
108. that the wetting of cells sometimes produces erroneous head changes in neighboring cells during the succeeding iteration which may cause erroneous conversions of those cells These erroneous conversions can be prevented by waiting a few iterations until heads have had a chance to adjust before testing for additional conversions When setting IWETIT greater than one there is some risk that cells may be prevented from correctly converting from dry to wet If the solution for a time step is obtained in less than IWETIT iterations then there will be no check during that time step to see if cells should be converted from dry to wet The potential for this problem to occur is greater in transient simulations which frequently require only a few iterations for a time step The method of wetting and drying cells used in the BCF2 Package can cause problems with the convergence of the iterative solvers used in MODFLOW Convergence problems can occur in MODFLOW even without the wetting capability but problems are more likely to occur when the wetting capability is used Symptoms of a problem are slow convergence or divergence combined with the frequent wetting and drying of the same cells It is normal for the same cell to convert between wet and dry several times during the convergence process but frequent conversions are an indication of problems As a matter of fact situations exist where the real solution oscillates such as in the case of a well causing a drawdo
109. the Open Model dialog box 2 To calculate the capture zone of the pumping well Click the Set Particle button Move the mouse cursor to the model area The mouse cursor turns into crosshairs Place the crosshairs at the upper left corner of the pumping well as shown in Fig 2 15 ce oO fF Hold down the left moust button and drag the crosshairs until the window covers the pumping well e Release the left mouse button 2 1 Run a Steady State Flow Simulation 28 Processing Modflow An Add New Particles dialog box appears Assign the numbers of particles to the edit fields in the dialog box as shown in Fig 2 16 Click the Properties tab and click the colored button to select an appropriate color for the new particles When finished click OK f To set particles around the pumping well in the second and third layer press PgDn to move down a layer and repeat steps c d and e Use other colors for the new particles in the second and third layers g Click J to start the backward particle tracking PMPATH calculates and shows the projections of the pathlines as well as the capture zone of the pumping well Fig 2 17 To see the projection of the pathlines on the cross section windows in greater details open an Environment Options dialog box by choosing Environment from the Options menu and set a larger exaggeration value for the vertical scale in the Cross Sections tab Fig 2 18 shows the same pathlines by setting
110. the fourth order Runge Kutta method is to calculate the particle velocity four times for each tracking step one at the initial point twice at two trial midpoint and once at a trial end point A weighted velocity based on values evaluated at these four points is used to move the particle to a new position The fourth order Runge Kutta method permits the use of larger tracking steps However the computational effort required by the fourth order Runge Kutta method is considerably larger than that required by the first order Euler method For this reason a mixed option combining both methods 1s introduced in MT3D The mixed option is implemented by automatic selection of the fourth order Runge Kutta algorithm for particles located in cells which contain or are adjacent to sinks or sources and automatic selection of the first order Euler algorithm for particles located elsewhere gt MXPART is the maximum number of particles allowed in a simulation gt PERCEL is the Courant number or number of cells or a fraction of a cell any particle will be allowed to move in any direction in one transport step Generally 0 5 lt lt gt WD is a concentration weighting factor between and 1 The value of 0 5 is normally a good 3 6 3 MT3D 122 Processing Modflow choice This number can be adjusted to achieve better mass balance Generally it can be increased toward 1 as advection becomes more dominant gt DCEPS is a criterion for
111. the vertical exaggeration value to 10 Note that some pathlines end up at the groundwater surface where recharge occurs This 1s one of the major differences between a three dimensional and a two dimensional model In two dimensional areal simulation models such as ASM for Windows Chiang et al 1998 FINEM Kinzelbach et al 1990 or MOC Konikow and Bredehoeft 1978 a vertical velocity term does not exist or always equals to zero This leads to the result that pathlines can never be tracked back to the ground surface where the groundwater recharge from the precipitation occurs PMPATH can create time related capture zones of pumping wells The 100 days capture zone shown in Fig 2 19 is created by using the settings in the Particle Tracking Time Properties dialog box Fig 2 20 and clicking E To open this dialog box choose Particle Tracking Time from the Options menu Note that because of lower hydraulic conductivity and thus lower flow velocity the capture zone in the first layer is smaller than those in the other layers 2 Run a Steady State Flow Simulation Processing Modflow w PMPATH sample pm5 29 T T eee 4 749E 02 3242E 02 7 038E 00 24141 80763E 00 7 3990E 06 1 7199E 07 1 1 0 Add New Particles Fig 2 16 T
112. to change contour color if you desire If Fill Contours is checked the contours will be filled with the colors given in the Fill column of the table Use the Label Format button to specify an appropriate format 3 Click OK to exit the Environment Options dialog box Contours should now appear and if everything has gone well they will look similar to Fig 6 4 Note the display of the model grid is deactived by using the Environment Options dialog box You may use File Save Plot As or File Print Plot to save or print the plot Leave the Presentation by File Leave Editor Yes 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge Processing Modflow 22 ugs ge al ogge ooo Qual Well 1 Well 2 Well B Or a Do cer ie Well 4 Well 5 E Wall Y Wall H Well 8 a H a Fig 6 4 Steady state head distribution Step 8 Transient Flow Simulation Initial Hydraulic Head It is now time to perform the transient simulations with the wet season recharge 120 days and dry season pumping 240 days The hydraulic heads resulting from the steady state simulation are used as the starting heads for the transient analysis v To set the steady state heads as the starting values for the simulation Select Parameters Initial Hydraulic Heads Open the Browse Matrix dialog box by Value Matrix In the Browse Matrix dialog box select Load to open the Load Matrix dialog bo
113. to have hands on experience with the practical application of models Twenty documented problems complete with problem statements input data sets and discussion of results are presented in that manual The problems are designed to cover modeling principles specifics of input output options available to the modeler rules of thumb and common modeling mistakes You can find an electronic version of this manual in the folder Documents Instructional Problems for MODFLOW EPA on the companion CD ROM Modeling Approach and Simulation Results We have rebuilt most of the models described in the manual of instructional problems If you have selected to install the Example Pack EPA instructional problems during the installation of PMWIN you can find the models in sub folders under om5 examples EPA Instructional Problems Although these models are ready to run it is suggested to construct the models by yourself because one will learn more through mistakes and exercises 6 3 EPA Instructional Problems 270 Processing Modflow 6 4 Automatic Calibration and Pumping Test 6 4 1 Basic Model Calibration Skill with PEST UCODE Folder pm5 examples calibration calibration 1 Overview of the Problem Groundwater models are usually applied to conceptualize and understand a hydrologic system or to predict the outcome of a future change to the system In order to provide some assurance that the model reflects the behavior or appearance of the flow system
114. to right on the status bar The parameter number is used to assign the Recharge Flux I as a parameter for an automatic calibration by the inverse models PEST see PEST gt Parameter List or Parameter List Note that although these values are specified for each vertical column of cells you may move to other layers within the Data Editor and examine the grid configuration in each layer Recharge Flux 25E08 Layer Indicator RCH 0 Parameter Number o Recharge Options C Recharge is only applied to the top grid layer C Recharge is applied to the highest active cell Current Position Column Row 33 14 he recharge option is applied to the entire matrix IRCH is only required if he second recharge option is selected Cancel Help Fig 3 20 The Recharge Package dialog box MODFLOW uses Ip to calculate the recharge flow rate LT applied to the model cell Q4 lp DELH DELC 3 15 where DELR is the map area of a model cell In MODFLOW the recharge rate Qp is applied to a single cell within a vertical column of cells In the simplest situation the water table is located 1n the top layer of the model the top layer 1s designated as unconfined and an array of Recharge Flux lp is specified for that layer Problems may arise when the water table cuts across layers To solve this kind of problems the Recharge package provides thr
115. to the second layer by pressing PgDn Choose Reset Matrix from the Value menu or press Ctrl R type 0 00005 in the dialog 2 Run a Steady State Flow Simulation 16 Processing Modflow box then click OK 5 Repeat steps 3 and 4 to set the value of the third layer to 0 00005 6 Choose Leave Editor from the File menu or click the leave editor button ge gt specify the effective porosity 1 Choose Effective Porosity from the Parameters menu Because the standard value is the same as the prescribed value of 0 25 you may leave the editor and save the changes 2 Choose Leave Editor from the File menu or click the leave editor button ge gt Tospecify the recharge rate 1 Choose MODFLOW Recharge from the Models menu 2 Choose Reset Matrix from the Value menu or press Ctrl R enter SE 9 for Recharge Flux L T in the dialog box then click OK 3 Choose Leave Editor from the File menu or click the leave editor button ge The last step before performing the flow simulation 1s to specify the location of the pumping well its pumping rate In MODFLOW an injection or pumping well is represented by a node or a cell The user specifies an injection or pumping rate for each node It 1s implicitly assumed that the well penetrates the full thickness of the cell MODFLOW can simulate the effects of pumping from a well that penetrates more than one aquifer or layer provided that the user supplies the pumping rate for
116. using the Reservoir Package dialog box Fig 3 21 of the Data Editor to assign the following values to the model cells Reservoir Number Ipes Land surface elevation of the reservoir Bees L Vertical hydraulic conductivity of the reservoir bed HCpes L T Thickness of the reservoir bed Rb L and Layer Indicator IRESL Parameter Number The parameter number is used to assign as a parameter for an automatic calibration by the inverse models PEST or UCODE see PEST Parameter List or UCODE Parameter List The elevation of the water table in reservoirs are specified by using the Stage Time Table of Reservoirs dialog box see below The land surface elevation within the specified area of potential inundation for each reservoir 1s typically defined by the average land surface elevation 3 6 MODFLOW Processing Modflow 89 of individual cells within the area At cells in which reservoir stage exceeds land surface elevation within the specified reservoir area the reservoir boundary is activated Similarly wherever reservoir stage is less than the land surface elevation of a cell the reservoir boundary is not activated If reservoir stage drops below the lowest land surface elevation for all cells within the specified reservoir area water exchange 1s not simulated between the reservoir and the underlying groundwater system In active cells water exchange between surface water and gro
117. using the upstream finite difference method The numerical dispersion is significant when the upstream finite difference method is used to solve the advection term 11 10 Injection well Q 1 E Observation borehole 300 m fixed head boundary h fixed head boundary h 450 m aT Fig 6 59 Configuration of the model and the location of an observation borehole Fig 6 60 Calculated concentration distribution 6 6 2 Two Dimensional Transport in a Uniform Flow Field Processing Modflow 299 1 909 1 numerical solution c N c _ analytical solution a o 0 0 1 0 3 hbE 2 Simulation time days Fig 6 61 Comparison of the breakthrough curves at the observation borehole The numerical solution 1s obtained by using the 3rd order TVD scheme 83E 1 m 2 numerical F c solution ium Led I analytical e solution O E 0 1 E 0 3 BBE Simulation time days Fig 6 62 Comparison of the breakthrough curves at the observation borehole The numerical solution is obtained by using the upstream finite difference method 6 6 2 Two Dimensional Transport in a Uniform Flow Field 300 Processing Modflow 6 6 3 Benchmark Problems and Application Examples from Literature Folder pm5 examples transport Overview of the Problems To test the accuracy and performance of the MT3D MT3DMS and MOC3D codes sev
118. values can be specified for different stress periods A time variant specified concentration cell is defined by specifying the following data in 3 6 3 MT3D Processing Modflow 129 the Data Editor Note that Time Variant Specified Concentration may not be supported by some earlier version of MT3D Flag A non zero value indicates that a cell is specified as a constant concentration cell In a multiple stress period simulation a constant concentration cell once defined will remain a constant concentration cell in the duration of the simulation but its concentration value can be specified to vary in different stress period To change the concentration value in a particular stress period simply set a non zero value to Flag and assign the desired concentration value to Specified Concentration Specified Concentration ML This value is the concentration in the cell from the beginning of a stress period MT3D gt Output Control Use the Output Control MT3D MT3DMS dialog box Fig 3 45 to set the output options from MT3D The options in this dialog box are grouped under three tabs described below Output Terms The MT3D transport model always generates a listing file OUTPUT MT3 which documents the details of each simulation step Optionally you can save other output terms by checking the corresponding output terms in this tab All output terms denoted by ASCII are also saved in the listing file The calculated conce
119. variable head cells either immediately below or horizontally adjacent to the dry cell can cause the cell to become wet When a cell is wetted its IBOUND value 15 set to 1 which indicates variable head cell vertical conductances are set to the original values and the hydraulic head h at the cell is set by using one of the following equation h BOT WETFCT hn BOT 3 28 h BOT WETFCT THRESH 3 29 3 6 1 MODFLOW Processing Modflow 99 where hn is the head at the neighboring cell that causes the dry cell to wet and WETFCT is a user specified constant called the wetting factor You may select between eq 3 28 and 3 29 in the Wetting Capability dialog box Fig 3 27 This dialog box appears after selecting Wetting Capability from the Models menu Wetting Capability EW Iteration Interval for amp ttemping ta Wet Cells Wetting Factor WETFCT Initial Heads at Rewetted Cells h BOT WETFCT ihn BOT C h BOT WETFCT THRESH BOT Bottom of cells HRESH Vetting threshold hn heads atthe neighboring cells Click OR to edit wetting threshold Cancel Help Fig 3 27 The Wetting Capability dialog box The dialog box also allows you to specify the iteration interval for attempting to wet cells IWETIT Wetting is attempted every IWETIT iterations When using the PCG2 solver Hill 1990 this applies to outer iterations and not inner iterations The reason for adjusting IWETIT is
120. velocity components across each cell face Pollock s semi analytical particle tracking scheme is based on the assumption that each directional velocity component varies linearly within a model cell in its own coordinate direction The semi analytical particle tracking algorithm uses simple linear interpolation to compute the principle velocity components at any points within a cell Given the starting location X y Z of the particle and the starting time t the velocity components are expressed in the form V t 2 A Xx B X Va 4 4a v t Ay 7 yi t V 4 4b v t E 2 i 24 t 4 4c where X y and Z are defined in Fig 4 3 A A and A T are the components of the velocity eradient within the cell A Vo i V4 Ax 4 5a A Vo V4 Ay 4 5b A V V4 AZ 4 5c Using a direct integration method described in Pollock 1988 and considering the movement of the particle within a cell the particle location at time t is x t x v t e vA IA 4 6a y t y vh eA vy 4 6b z t z v t e v A 4 6c where AT t For steady state flow fields the location of the particle at time t must be still within the same cell as at time t Given any particle s starting location within a cell at time t Pollock s algorithm allows to determine the particle s exit time t and exit point from the cell directly without having to calculate the actual
121. very slow An inspection of the PEST run record by pressing the ESC key will often show whether you have set these values too low for PEST records the maximum parameter factor and relative changes are recorded on this file at the end of each optimization iteration If these changes are always at their upper limits and the estimation process is showing no signs of instability it is quite possible that RELPARMA X and or FACPARMAX are too low and could be increased Note that FACPARMAX can never be less than 1 RELPARMAX can be less than 1 as long as no parameter s upper and lower bounds are of opposite sign If necessary use OFFSET to shift the parameter domain so that it does not include zero FACORIG is a criterion for modifying RELPARMAX and FACPARMAX If in the course of an estimation process the absolute value of a parameter falls below the product 3 6 5 PEST Inverse Modeling 150 Processing Modflow of FACORIG and its original value then the product is substituted for the denominators of eq 3 55 or eq 3 56 to prevent the denominators becoming zero or too small FACORIG is not used to adjust limits for log transformed parameters FACORIG must be greater than zero A value of 0 001 is often adequate PHIREDSWH is acriterion for switching the calculation method of derivatives between the forward finite difference method and the central finite difference method If for the i th iteration the relative reduction in the objective f
122. where DELR DELC is the map area of a model cell Qe is drawn from only one cell in the vertical column beneath the map area The Evapotranspiration package provides two options for specifying the cell in each vertical column of cells where evapotranspiration is drawn from 1 Evapotranspiration is always drawn from the top layer of the model 2 Vertical distribution of evapotranspiration is specified in the Layer Indicator Array lg defines the layer where evapotranspiration 1s drawn from In either case the Qe has no influence on the simulation if the designated cell is either a no flow inactive cell or a constant head cell You can select an option in the Evapotranspiration Package dialog box The layer indicator array is needed only when the second option is used MODFLOW General Head Boundary The General Head Boundary package is used to simulate head dependent flow boundaries Cauchy boundary conditions Similar to the Drain package a General Head Boundary cell GHB cell is defined by three cell values GHB hydraulic conductance C L T Hydraulic head at the boundary h L Paramter Number The parameter number is used to assign C as a parameter for an automatic calibration by the inverse models PEST or UCODE see PEST Parameter List or UCODE Parameter List Flow through the general head boundary Q LT is calculated by Q C h h 3 9 where h is the hydraulic head in the aquife
123. wide by 6 000 ft long 1s divided into six equally spaced rows and columns The transmissivity of the aquifer is 0 08 ft s Recharge to the aquifer occurs only from stream leakage The example includes 7 stream segments with totally 16 reaches There is one diversion segment 2 and two places where streams join segments 2 and 4 join to make segment 5 and segments 3 5 and 6 join to make segment 7 Stream stages are also computed for each reach The streams range in width from 5 to 10 ft Streambed conductance values also vary depending on the length and width of each stream reach The hydraulic conductivity of the streambed deposits is 4 x 10 ft s Solution from equation 5 Flow assigned to stream for each stress period Streamflow in thousands of cubic feet per second 8 10 20 30 40 50 60 70 80 90 Time in days since start of flood Fig 6 29 Distribution of streamflow for a 30 day flood event used for the simulation after Prudic 1988 Stream stage in feet above sea level 10 20 30 40 50 60 70 S0 90 Time in days since start of flood Fig 6 30 Model calculated river stage 6 2 7 Simulation of a Flood in a River Processing Modflow 265 Columns stream segment dots indicate section of stream used to define a segment Arrow indicates the direction of flow 3 segment number 2 reach number within a segment section of st
124. with PEST select this menu item The available settings of the Run PEST dialog box Fig 3 54 are described below gt Modflow Version and Modflow Program Several variants of MODFLOW are included in PMWIN PMWIN automatically installs the executables of these variants Their full paths and filenames are given in table 3 4 If you want to use a compiled version located in an other position click the open file button E and select the desired code from a dialog box The User s own version must be selected 1f you want to use your own version of MODFLOW Refer to Appendix 5 for how to configure PMWIN to run with your own MODFLOW gt PEST Program There are four variants of PEST which are named PESTLITE PESTLM PESTSW and PESTEM PESTLITE included in PMWIN is an educational version of PESTLM and is restricted to 4 parameters and 80 observations Use of the other three variants 1s identical however they each use your machine s memory in a different way PESTLM 1s the most basic of the three It uses conventional DOS memory limited to 640k staying resident in this memory when it runs MODFLOW PESTSW is identical to PESTLM except it vacates the conventional memory as it calls MODFLOW PESTEM uses your machine s extended memory and executes faster as it was compiled with a 32 bit compiler However an unsolved memory problem will occur if you run PESTEM within Windows The problem is probably caused by the operating system or the
125. 00 00 7383324E 03 0000000 00 00000U0 UE UD 8930938E 03 0000000 E 10 0000000 00 0000000 00 26314263803 IN OUT 0000000 00 9542770 05 0000000 00 0000000 00 5872560E 03 0000000E 10 0000000 00 6880163E 03 1217543E 05 IN OUT 0000000 00 3562248E 04 0000000 00 5872560E 03 8930938E 03 0000000E 10 0000000 00 0000000 00 1460386E 05 WATER BUDGET OF SELECTED ZONES ZONE 1 ZONE 2 2a ot IN 8720924E 03 5899659E 03 OUT 8308751E 03 6314263E 03 IN OUT 1217310E 05 1460386E 05 WATER BUDGET OF THE WHOLE MODEL DOMAIN FLOW TERM STORAGE CONSTANT HEAD WELLS DRAINS RECHARGE IN 0000000 00 2149608E 03 0000000 00 0000000 00 26880163803 OOF OUT 0000000 00 7026911E 03 2000003E 03 0000000 00 0000000 00 IN OUT 0000000 00 4877303603 2000003E 03 0000000 00 698801635E 03 DISCREPANCY Ihe value of the element rate from the i th zone into the j th zone 9029770E 03 01 1 9 index j is the row index FLOW MATRIX 1 O 1 0 0000 0O 2 2 5873E 03 0 0000 0000 9026916E 03 8545037E 07 of the following flow matrix gives the flow Where i is the column 2 Run a Steady State Flow Simulation 22 Processing Modflow In this example the percent discrepancy of in and outflows for the model and each zone in each
126. 00 cece eee eee eee eee eens BCF DAT Density Package DENT 229 uo R cee bee clans ee eee eee E URN RE Pp eet eed DEN1 DAT Direct Solution Package DE45 eee rrr DE45 DAT ee esae eee a ee ee ee ae en dor ee re ee DRN DAT Evapotranspiralion Package a 1 5 3 519 a Ie hoe Sho Sen a P sie aca P uh Sem duds uia het EVT DAT General Head Boundary Package l l GHB DAT Horizontal Flow Barrier Package suede baie ieee baie fnew late hse baie HFB1 DAT Interbed Storage Package IBS1 DAT OIBDHEGOLU OL s tata entem Shit ier Aet hoa hiuc hix hix dtu Aii tae us OC DAT Preconditioned Conjugate Gradient 2 Package PCG2 PCG2 DAT ind V2 8 mare 6 clo eer PU ee RIV DAT Recharge Packie es doa tow tae eee eas a a ee RCH DAT MeSelVOll Package s vss mart eoe on uide So Mon anu Aa d b a uoi S BE ae Ae eh B ion nutem RES1 DAT Strongly Implicit Procedure Package SIP DAT Slice Successive Overrelaxation Package SOR DAT Stream Routing Flow Package 0 ccc ee eee ee eee eens STR1 DAT Time Variant Specified Head 0 0 0c eee ee eee eee eee CHD1 DAT AH We Rp rmm RE Yee WEL DAT MODPATH and MODPATH PLOT version 1 x Main ata tile oscec
127. 052 24660 0 529 493 0 077 35228 0 564 1233 0 168 49320 0 595 2466 0 25 123300 0 652 3523 0 294 6 4 4 Transient Flow to a Well in a Leaky Confined Aquifer 280 Processing Modflow Pumping rate Q 0 004 m s impervious im Overlying aquifer K 1 0E 5 m s Kv 1 0E 6 m s 3 75E4 1E 7 m s Aquitard _ 1 8 mis 1 4 2 3E 4 m s 2 3E5 mis 7 5E 4 Leaky confined aquifer 10 impervious K horizontal hydraulic conductivity Kv vertical hydraulic conductivity S confined storage coefficient Fig 6 41 Configuration of the leaky aquifer system and the aquifer parameters Modeling Approach and Simulation Results The modelled domain is the same as in the previous example Three model layers are used to simulate the system The layer types are 3 confined unconfined transmissivity varies In the Layer Options dialog box the Storage Coefficient flag is set to user specified and the Transmissvity flag is calculated All model cells in the first model layer are fixed head cells and all other cells are specified as active cells A transient flow simulation 1s performed for a stress period with the length of 49320 seconds 20 time steps and a time step multiplier of 1 3 For comparison the analytical solution is entered in the Boreholes and Observations dialog box Fig 6 42 shows the numerical and analytical drawdown time curves at the observation borehole which i
128. 0E OU L 8 20E 0G6 _ lt lt D L B 8 40E E00 4 d E 5 ES LX 05 9E 09 S 80E 00 8 80E 4 00 ma x aner9 P7 1 2 306400 constant head boundary h 9 m OECD DLL L 8 70E800 T L5 08 FUo 3 Ig 60E 0D tT 6E oo 24860E 4 00 BB OE 00 6 90E 00 8 90E 00 ___ BLE 00 40 0 LL ERSO 00 _ s Ci j 8 50 00 Q 73 x lt 592 5117 358 5023 Steady state Recycle H 9 Fig 2 14 A contour map of hydraulic heads in the first layer gt To delineate the capture zone of the pumping well 1 Choose PMPATH Pathlines and Contours from the Models menu PMWIN calls the advective transport model PMPATH and the current model will be loaded into PMPATH automatically PMPATH uses a grid cursor to define the column and row for which the cross sectional plots should be displayed You can move the grid cursor by holding down the Ctrl key and click the left mouse button on the desired position Note that if you subsequently modify and calculate a model within PMWIN you must load the modified model into PMPATH again to ensure that the modifications can be recognized by PMPATH To load a model click and select a model file with the extension PMS from
129. 1 65 Time independent Horizontal Hydr Conductivity L T 0001 0 Fig 3 6 The Data Editor real world display mode 3 2 The Data Editor Processing Modflow 61 3 2 1 The Cell by Cell Input Method To activate this method click the cell by cell button choose Input Method gt Cell By Cell from the Options menu gt assign new value s to a cell 1 Click the assign value button You do not need to click this button if its relief 1s already sunk 2 Move the grid cursor to the desired cell by using the arrow keys or by clicking the mouse on the cell The value s of the current cell will be shown in the status bar 3 Press the right mouse button once The Data Editor shows a dialog box 4 Inthe dialog box type new value s then click OK gt To check modify cell value s 1 Double click a cell the Data Editor will highlight the cells that have the same value as the clicked cell 2 Hold down the Shift key and press the left mouse button to open a Cell Infomation dialog box Fig 3 7 for checking but not editing the user specified data of the cell under the grid cursor 3 Hold down the Ctrl key and press the left mouse button to open a Search and Modify Cell Values dialog box Fig 3 8 This allows you to display all cells that have a value located within the Search Range to be specified According to the user specified Value and the operation Options you can easily modify the cell val
130. 1 DAT Sink amp Source Mixing MTMSSSM1 DAT PEST Erst eos din tst mato INSTRUCT DAT Control Bile 3o xu REX eX RO EUR RR DA ERU hac tarta e a ed PESTCTL DAT Block Centered Flow Package Template File BCFTPL DAT Dran Package template File iss Cacus gaat eae gs Re ee ee DRNTPL DAT Evapotranspiration Package Template File EVITPL DAT General Head Boundary Package Template File GHBTPL DAT Recharge Package Template RCHTPL DAT HiVersackage Templalte RllB i Silat tie heed ueque Set ithe aures Rees eae eee ars EUR RIVTPL DAT Well Package Template File kote hohe ieee bois WELTPL DAT Stream Routing Flow Package Template File SIRTPL DAT Interbed Storage Package Template File IBSTPL DAT Grid Specification File used by MODBORE EXE filename GRD Borehole Listing File used by MODBORE EXE BORELIST DAT Borehole Coordinates File used by MODBORE EXE BORECOOR DAT See appendix 2 for the format of the grid specificati
131. 1972 6 2 6 Simulation of an Aquifer System with irregular Recharge and a Stream Processing Modflow 263 6 2 7 Simulation of a Flood in a River Folder pm5 examples basic basic 7 Overview of the Problem This example is the second test problem of the STRI package The function of the STRI package that computes the head in the stream as well as changes in flows to and from the aquifer was compared to an analytical solution developed by Cooper and Rorabaugh 1963 The model grid used in the previous example was also used in this model The aquifer properties and assumptions are the same as those used in the previous example except for assumptions 8 10 which are replaced with the following assumptions 1 The recharge to the aquifer is only from the river as river stage increases with time and 2 The discharge from the aquifer is only to the river as river stage decreases with time The analytical solution from Cooper and Rorabaugh 1963 p 355 358 1s applicable for the case where the lateral boundary is at infinity referred to by Cooper and Rorabaugh as semi infinite The impermeable boundary assigned at 4 000 ft for this model is of sufficient distance from the river in order not to interfere with the results A flood in the river was simulated for a 30 day period The procedure used to calculate the distribution of streamflow for the 30 day period and for 60 days following the flood was first to calculate a distribution of river sta
132. 2 Add VALUE is added to the cell values OPTIOn 3 Multiply The cell values are multiplied by VALUE Zone file A zone file can be saved or loaded by the Data Editor by using the item Zones from the Value menu Appendix 2 Files and Formats Processing Modflow LABEL NZONES XXX XXX XXX XXX The following data data 3 6 repeat NZONES times 314 File Format 1 Data 2 Data 3 Data 4 Data 5 Data NP PARNO Value 1 Value 2 Value 3 Value l Value 16 The following data repeats NP times 6 Data X J Y J Explanation of Fields Used in Input Instructions ALL DATA IN THE SAME RECORD ARE SEPARATED BY A COMMA OR BLANK LABEL NZONES XXX NP PARNO Value l is the file label It must be PMWIN4000 ASCII ZONEFILE is the number of zones Maximum is 20 reserved is the number of nodes of each zone The first and the last node must overlap The maximum number of NP is 41 is the assigned parameter number see section 3 3 6 for how to define an estimated paramter 1 to 16 Value l are the zone values For aquifer parameters such as porosity or transmissivity only the first value or two values if a parameter number can be defined is used For MODFLOW packages such as Drain Package as many values as required by the package are used For example two values Hydraulic conductance and the elevation of the drain required for defining a drain will be saved in Value 1 and Value 2 Other va
133. 210 Processing Modflow 5 5 The Water Budget Calculator There are situations in which it is useful to calculate flow terms for various subregions of the model To facilitate such calculations the computed flow terms for individual cells are saved in the file BUDGET DAT These individual cell flows are referred to as cell by cell flow terms and are of four types 1 cell by cell stress flows or flows into or from an individual cell due to one of the external stresses excitations represented in the model e g pumping well or recharge 2 cell by cell storage terms which give the rate of accumulation or depletion of storage in an individual cell 3 cell by cell constant head flow terms which give the net flow to or from individual constant head cells and 4 internal cell by cell flows which are the flows across individual cell faces In the file BUDGET DAT the flow between the cells J I K and J 1 I K is denoted by FLOW RIGHT FACE the flow between the cells J I and J 1 1 K is denoted by FLOW FRONT FACE and the flow between the cells J I K and J I K 1 is FLOW LOWER FACE The Water Budget Calculator uses the cell by cell flow terms to compute water budgets for the entire model user specified subregions and in and outflows between adjacent subregions Refer to Step 5 Calculate subregional water budget of Section 2 1 for details 5 6 The Graph Viewer To activate the graph viewer select an appropriate menu i
134. 3D 34 Processing Modflow 2 Click OK to close the dialog box a Advection Package MTADY1 Solution Scheme Method of Characteristics MOC Particle Tracking Algorithm Firstorder Euler Max number of total moving particles MXFART Courant number FERCEL Concentration weighting factor WO Negligible relative concentration gradient Fatter for initial placement of particles NPLANE Mo of particles per cell in case of DCCELL DCEPS NFL No of particles per cell in case af DCCELLSDCEPS Minimum number of particles allowed per cell Maximum number of particles allowed per cell PMA Multiplier forthe particle number at source cells SRMULT 27 3 2 z gu Im m __ Max number of total moving particles MXPART Cowantnumber PERCEL M Concentration weighting factor WD 0 Negligible relative concentration gradient DCEPS No of particles per cell in case of DCCELL DCEPS NPL No of particles per cell in case of DCCELL gt DCEPS Minimum number of particles allowed per cell NPMIN Maximum number of particles allowed per cell NPMAX Cancel Help Fig 2 22 The Advection Package MTADV1 dialog box gt assign the dispersion parameters 1 Choose MT3D Dispersion from the Models menu A Dispersion Package MT3D dialog box appears Enter the ratios of the transverse dispersivity to lo
135. 3DMS You can start the simulation at a later time by executing the batch file MT3DMS BAT Click OK to start the generation of MT3DMS input files In addition PMWIN generates a batch file MT3DMS BAT saved in your model directory When all necessary files are generated PMWIN automatically runs MT3DMS BAT in a DOS window During a flow simulation MT3DMS saves results to various output files and writes a detailed run record to the listing file OUTPUT MTM saved in your model folder 3 6 4 MT3DMS 140 Processing Modflow Run MT3DMS Eq MT3DMS Program BN filles pm5 mt3dms mt3dms exe r Basic Transport Package c program fileskipmb5examplesYsamplel Advection Package c program files pm5 examples samplel Dispersion Package c program files pm5 examples samplel Chemical Reaction Package c program files pm5 examples samplel Generalized Conjugate Gradient Solver l c program files jpm5 examples samplel Sink and Source Mixing Package c program files pm5 examples samplel Options Regenerate all input files for MT3DMS Generate input files only don t start MT3DMS Cancel Help Fig 3 52 The Run MT3DMS dialog box 3 6 5 PEST Inverse Modeling This menu provides an interface between PMWIN the flow model MODFLOW and the inverse model PEST Depending on the layer type see Grid Layer Type the parameters and or excitations listed 1n Table 3 7 can be adjusted until model generated numbers
136. 4 The Stream Structure table of the Streamflow Routine Package dialog box segment 1 segment 4 segment 3 segment 5 Fig 3 25 The configuration of the stream system specified in the table of fig 3 24 3 6 MODFLOW 96 Processing Modflow MODFLOW Time Variant Specified Head For transient simulations the Time Variant Specified Head package Leake and Prudic 1991 allows fixed head cells to take on different head values for each time step The following required data are specified by using the Time Variant Specified Head Package dialog box Fig 3 26 of the Data Editor A non zero value indicates that a cell is specified as a time variant specified head boundary Start Head h L This value is the head in the cell at the start of the stress period End Head h L This value is the head that will be assigned to the cell for the last time step in the stress period This package does not alter the way fixed head boundaries are formulated in the finite difference equations of MODFLOW It simply sets the element in the IBOUND array to a negative value for all cells where a time variant specified head boundary is selected Flag 0 The package linearly interpolates boundary heads h for each time variant specified head boundary cell by using the equation PERTIM h h h Z s Ue BERLEN 3 25 where PERTIM is the starting time of a time step in a stress period and PERLEN is the length o
137. 6 Du The Results Extractor coude Sus Gus 9220 0 ee E Und an UR ewe MEUSE D CIC 208 5 9 The Water Balance Calculator EX Xe Xa ER exe 210 2 0 Whe Graph Viewer 210 Examples and Applications 215 oW WOMANS here 215 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge 215 6 1 2 Tutorial 2 Confined and unconfined Aquifer System with River 232 0 2 Basic Flow Problems bike at hes tthe ee hes ACER AIO C c a 244 6 2 1 Determination of Catchment Areas 244 6 2 2 Use of the General Head Boundary Condition 248 6 2 3 Simulation of a Two layer Aquifer System in which the Top Layer Converts between Wet and Dry 250 6 2 4 Simulation of a Water table Mound resulting from Local Recharge 253 6 2 5 Simulation of a Perched Water Table 254 6 2 6 Simulation of an Aquifer System with Irregular Recharge and a Stream 260 6 2 7 Simulation of a Flood ina River 263 6 2 8 Simulation OP Lakes 952 wa Se o oscar OR oa nC te E oca De E our a CS 266 6 3 EPA Instructional Problems 269 6 4 Automatic Calibration and Pumping 270 6 4 1 Basic Model Calibration Skill with PEST UCODE 270 6 4 2 Estimation of Pumping Rates
138. 85281 8 485281 84 85281 8 485281 84 85281 8 485281 84 85281 8 485281 84 85281 8 485281 84 85281 8 485281 84 85281 Label Format Restore Defaults Load Save Cancel Help Fig 3 65 The Contours tab of the Environment Options dialog box Display zones in the cell by cell mode i Color Spectrum Eq Minimum Color Maximum Color NEN OK Cancel Help Fig 3 66 The Color Spectrum dialog box 3 9 The Options Menu 170 Maps Processing Modflow Contour Labels First labeled contour line Labeled line frequency Fig 3 67 The Contour Labels dialog box L abel Format Fixed C Exponential Decimal digits 2 Pretix Suffix Fig 3 68 The Label Format dialog box The Maps Options dialog box Fig 3 69 allows you to display up to 5 background DXF maps 3 Line maps and one geo referenced raster bitmap graphics The options in this dialog box are grouped under two tabs described below gt Vector Graphics A DXF file contains detailed data describing numerous CAD entities An entity is a line or symbol placed on a drawing by the CAD system PMWIN supports the following entities LINE POLYLINE POINT ARC SOLID CIRCLE and TEXT The other entities will be ignored There is no size limit to the number of the acceptable entities A Line Map consists of a series of polylines Each
139. 888 m d each during the 8 month dry season to supply water for irrigation and domestic purposes Your task is to assess the water levels in the aquifer under the following conditions l steady state with the mean recharge rate 2 5x10 m day no pumping 2 after 8 months pumping during the dry season and 3 the water levels by the end of the following wet season 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge 216 Processing Modflow Fixed head h 15 m well well2 well 3 m m m well 4 well 5 well 6 u No flow boundary No flow boundary well 7 well8 well 9 a Specified Flux Boundary 0 0672 mJ day m Fig 6 1 Plan view of the model area There are eight main steps in this tutorial Create a new model Define model size Refine model grid Assign model data Perform steady state flow simulation Extract and view results from the steady state simulation Produce output from the steady state simulation and Transient flow simulation This tutorial will lead you through the steps required to construct a working groundwater model of the area being studied and to then use the model to assess the effects of changing some parameters on the modelled results Instructions are given for each step of the process in the following manner Select items from the menu in BOLD series of commands linked by gt for example to open a new model the steps are File N
140. A Boreholes and Observations dialog box appears Enter the coordinates of the observation boreholes into the dialog box as shown in Fig 2 21 2 Click OK to close the dialog box Boreholes and Observations Boreholes Observations ce pDoooOoOoODOOOOCD O O0 60 0 09 oo oc oo Co 4 4 4 Save Load Clear Cancel Help Fig 2 21 The Boreholes and Observations dialog box The Modeling Environment 3 1 The Grid Editor Processing Modflow 33 2 2 1 Perform Transport Simulation with MT3D MT3D requires a boundary condition code for each model cell which indicates whether 1 solute concentration varies with time active concentration cell 2 the concentration is kept fixed at a constant value constant concentration cell or 3 the cell 1s an inactive concentration cell Use 1 for an active concentration cell 1 for a constant concentration cell and O for an inactive concentration cell Active variable head cells can be treated as inactive concentration cells to minimize the area needed for transport simulation as long as the solute concentration is insignificant near those cells Similar to the flow model you must specify the initial concentration for each model cell The initial concentration at a constant concentration cell will be kept constant during a transport simulation The other concentration are starting values in a tran
141. Ay R 4 9 Q mAx Ay R 4 9 Erase particle You can only erase particles located in the current layer The current layer 1s shown in the tool bar Change it first if you need to erase particles in another layer v To delete particles Click the Erase particle button Move the mouse cursor to where you want a corner of the Erase window Drag the mouse cursor until the window covers the particles which will be deleted BOUM c Release the mouse button Zoom In By default PMPATH displays the entire model grid Zoom in is useful if you want to view a part of the model domain in greater detail or if you want to save plots of a certain part of the model area see Sec 4 4 for how to save plots 4 2 PMPATH Modeling Environment 186 Processing Modflow v To zoom in on a part of the model Click the Zoom In button a Move the mouse cursor to where you want a corner of the Zoom window Drag the mouse cursor until the window covers the model area which is to be displayed BG E us Release the mouse button Zoom Out Clicking on the Zoom out button forces PMPATH to display the entire model grid S Particle color Clicking on the Particle color button allows a user to select a color for new particles from a Color dialog box Particles with different colors are useful when for example you want to determine the capture zones of several pumping wells In this case particles with a certain color
142. CBC Effective porosity SCC CBC otorage coefficient STO CBC opecific storage TAL CBC Longitudinal dispersivity YLD CBC Specific yield 63 CBC Parameter numbers associated with horizontal hydraulic conductivity 64 CBC Parameter numbers associated with vertical hydraulic conductivity 65 CBC Parameter numbers associated with specific storage 66 CBC Parameter numbers associated with transmissvity 67 CBC Parameter numbers associated with vertical leakance 68 CBC Parameter numbers associated with storage coefficient 69 CBC Parameter numbers associated with specific yield COZ ZONE horizontal hydraulic conductivity HTZ ZONE LEZ ZONE Vertical hydraulic conductivity LKZ ZONE Vertical leakance POZ ZONE Effective porosity Appendix 4 Internal Data Files of PMWIN Processing Modflow SCZ ZONE STZ ZONE YLZ ZONE 163 ZONE 164 ZONE 165 ZONE 166 ZONE 167 ZONE 168 ZONE 169 ZONE BCF2 Package Extension Type DWA CBC DWZ ZONE Density Package Extension Type C37 CBC Z37 ZONE Drain Package Extension Type DRC CBC DRE CBC 291 CBC DCZ ZONE 319 Storage coefficient Specific storage Specific yield Parameter numbers associated with horizontal hydraulic conductivity Parameter numbers associated with vertical hydraulic conductivity Parameter numbers associated with specific storage Parameter numbers associated with transmissvity Parameter numbers associated with vertical leakance P
143. Catchment Areas 248 Processing Modflow 6 2 2 Use of the General Head Boundary Condition Folder pm5 examples basic Woasic2 Overview of the Problem This simple example demonstrates the use of the general head boundary package of MODFLOW A confined homogeneous and isotropic aquifer is shown in Fig 6 18 The aquifer is bounded by a no flow zones to the north and south The hydraulic heads at the west and east boundaries are 12m and 10m respectively The transmissivity of the aquifer is T 0 01 m s The aquifer has a constant thickness of 10 m Your task is to calculate the head contours for the case that only the west part of the aquifer is modelled The east boundary of the modelled part should be approached by using the general head boundary 10m fixed head boundary h 12m general head boundary 1000 m fixed head boundary h 1550 m 1000 m Fig 6 18 Plan view of the model area Modeling Approach and simulation results The aquifer is simulated using a grid containing 1 layer 10 rows and 16 columns A regular grid spacing of 100 m is used for each column and row The layer type is 0 confined and the Transmissivity flag in the Layer Options dialog box is User specified The initial hydraulic head is 12 m everywhere While the west model boundary is simulated by the fixed head boundary condition IBOUND 1 with the initial head at 12 m the east boundary is simulated by the general head boundary GHB condition with the
144. ELE d EAE 65 oc Ue WOpOdVIe oc uoa sit Rs wy s Mts Spi T RS Au EUR T RSS E sint 69 Sud The Paraime ters sx ace Se dove aCS n CR o at ts e E oa ab oa tno a PR no a C 74 25 0 The Models Ment miedo e dc dede bs dex d des ded eds ded 80 DIODE OW tate baa 80 502 MOG D 111 Jaci wan xui USES NUUS eos eas EIE UI EU IE 119 132 3 6 5 PEST Inverse Modeling 140 3 6 6 DC ODE Inverse Modeling 154 3 6 7 PMPATH Pathlines and Contours 160 2 4 Eine Toob Menu 4091 ero ioo riore der Mo ede aded r sid sioe didi 160 2 5 Pie ae d VIC DU eo sot uh A pata A ot a EARN AU Eu 161 2 9 The Options 20 424 doe E dowd UR E EU A RS tues 165 The Advective Transport Model PMPATH 175 4 1 The Semi analytical Particle Tracking Method 176 42 PMPATH Modeling Environment 180 43 PMPATH Options Menu utei asia b PAS PAS SES 187 4 4 PMPATH Output Files 195 s Modeling 000195 eee wmm www wee women 199 S L SDHOJDISIHZCE hoa see hoa bee bee hee bee hee EAR 199 2 2 Ae Ere 200 30 Vhe PicldGenerator x52 942 amos SUE AURA comet aoe cama 20
145. Flow Simulation 22 Processing Modflow 2 2 Simulation of Solute Transport Basically the transport of solutes in porous media can be described by three processes advection hydrodynamic dispersion and physical chemical or biochemical reactions Both the MT3D and MOC3D models use the method of characteristics MOC to simulate the advection transport in which dissolved chemicals are represented by a number of particles and the particles are moving with the flowing groundwater Besides the MOC method the MT3D and MT3DMS models provide other methods for solving the advective term see sections 3 6 3 and 3 6 4 for details The hydrodynamic dispersion can be expressed in terms of the dispersivity L and the coefficient of molecular diffusion L T for the solute in the porous medium The types of reactions incorporated into MOC3D are restricted to those that can be represented by a first order rate reaction such as radioactive decay or by a retardation factor such as instaneous reversible sorption desorption reactions goverened by a linear isotherm and constant distribution coefficient In addition to the linear isotherm supports non linear isotherms 1 Freundlich and Langmuir isotherms Prior to running MT3D or MOC3D you need to define the observation boreholes for which the breakthrough curvers will be calculated gt define observation boreholes 1 Choose Boreholes and Observations from the Paramters menu
146. HDCG LCLRCH 1 LCIEQP MXITER NCOL NLAY NSLICE MBW IUNIT 11 IOUT IF IUNIT 13 GT 0 CALL PCG2AL ISUM LENX LCV LCSS LCP LCCD 1 LCHCHG LCLHCH LCRCHG LCLRCH MXITER ITER1 NCOL NROW NLAY 2 IUNIT 13 IJOUT NPCOND IF IUNIT 14 GT 0 CALL STR1AL ISUM LENX LCSTRM ICSTRM MXSTRM 1 NSTREM IUNIT 14 IOUT ISTCB1 ISTCB2 NSS NTRIB 2 NDIV ICALC CONST LCTBAR LCTRIB LCIVAR IF IUNIT 16 GT 0 CALL HFB1AL ISUM LENX LCHFBR NHFB IUNIT 16 1 IOUT IF IUNIT 19 GT 0 CALL IBS1AL ISUM LENX LCHC LCSCE LCSCV 1 LCSUB NCOL NROW NLAY IIBSCB IIBSOC ISS IUNIT 19 IOUT IF IUNIT 20 GT 0 CALL CHD1AL ISUM LENX LCCHDS NCHDS MXCHD 1 IUNIT 20 IOUT Appendix 5 Using PMWIN with your MODFLOW 326 Processing Modflow Appendix 6 Running MODPATH with PMWIN PMWIN supports both two versions version 1 x and 3 x of MODPATH and MODPATH PLOT You must run MODPATH or MODPATH PLOT within a DOS Box of Windows or in the DOS Environment If you are using MODPATH version 1 x released prior to September 1994 type path PATHFILE at the prompt ENTER NAME OF FILE CONTAINING NAMES AND UNITS OF DATA FILES Where path is the path to the directory of your model data PATHFILE contains the IUNIT assignments and paths and names of input data files generated by PMWIN The names of the input files for MODFLOW and MODPATH are given in Appendix 7 If you are using MODPATH or MODPATH PLOT version 3 x follow the steps below TO READ INPUT FROM AN EXISTING RESPONSE FILE EN
147. M PATH and MOC3D The cell by cell flow terms are saved in the unformatted binary file BUDGET DAT gt Subsidence is the sum of the compaction of all model layers for which the interbed strorage calculation is turned on see Layer Type in section 3 4 Compaction of individual layers is the sum of the calculated compaction and the user specified starting compaction in each layer Preconsolidation head is the previous minimum head value in the aquifer For model cells in which the specified preconsolidation head is greater than the corresponding value of starting head the preconsolidation head will be set to the starting head Subsidence compaction and preconsolidation head are saved in the unformatted binary file INTERBED DAT gt Interface file to MT3D is an unformatted binary file containing the computed heads fluxes across cell interfaces in all directions and locations and flow rates of the various sinks sources The interface file 1s created by the LKMT package provided by MT3D or MT3DMS There are three versions of the LKMT package which are incorporated in the versions of MODFLOW contained in the PMWIN see MODFLOW Run below The LKMT1 package creates interface file to the version 1 xx of MT3D The LKMT2 package creates interface file to MT3D96 and MT3D Dod 1 5 The LKMT3 package creates interface file to MT3DMS To check the simulation results MODFLOW calculates a volumetric water budget for the entire model at the
148. Mesh Size from the Grid menu The Model Dimension dialog box appears Fig 2 3 2 Enter3 for the number of layers 30 for the numbers of columns and rows and 20 for the size of columns and rows 2 Run a Steady State Flow Simulation 10 Processing Modflow The first and second stratigraphic units will be represented by one and two model layers respectively 3 Click OK PMWIN changes the pull down menus and displays the generated model grid Fig 2 4 PMWIN allows you to shift or rotate the model grid change the width of each model column or row or to add delete model columns or rows For our sample problem you do not need to modify the model grid See section 3 1 for more information about the Grid Editor 4 Choose Leave Editor from the File menu or click the leave editor button e Columns J 1 23456789 10 N IA S CIE AAL Layers K Fig 2 2 Spatial d discretization of an aue system and the cell indices ial Model Dimension Layers Number Cancel Columns Help Number Number 20 SIZE LEN Fig 2 3 The Model Dimension dialog box 2 Run a Steady State Flow Simulation Processing Modflow 11 J Processing Modflow SAMPLE PM5 ETE B 2 Layer Options 1 Unconfined Calculated Calculated E 0 Confined Calculated Calculated NE 0 Confined Calculated Calculated Fig 2 5 The Layer Options dialog box and the layer type drop down list
149. Processing Modflow 287 drain The selected model grid and the boundary conditions are shown in Fig 6 50 Except the four fixed head cells at the right hand side of the dam the initial hydraulic head for all cells are 10 m no flow boundary z10m fixed head boundary h fixed head boundary h 2m no flow boundary Fig 6 50 Model grid and the boundary conditions The first step in solving this problem is to carry out a steady state flow simulation with these data Fig 6 51 shows the calculated hydraulic heads By comparing the calculated heads with the elevation of the cell bottom we can easily find that the hydraulic heads of some of the cells at the upper right corner of the model are lower than the cell bottom This means that these cells went dry In the second step these dry cells will be defined as inactive cells by setting IBOUND 0 and a steady state flow simulation will be carried out again Now it 1s possible that some of the calculated heads are higher than the top elevation of the highest active cell In this case these cells will be defined as active and a steady state flow simulation will be performed again This iterative solution will be repeated until the water table remains unchanged between two iteration steps Fig 6 52 shows the calculated head distribution and the form of the seepage surface The seepage rate is about 4 8 x 10 m s m and the total seepage rate through the dam lenght 100 m is 4 8 x 10 m s
150. Reaction MOC3D dialog box appears Check Simulate Dispersion and enter the values as shown in Fig 2 31 Note that the parameters for dispersion and chemical reaction are the same for each layer Click OK to close the dialog box 2 2 2 Perform Transport Simulation with MOC3D Processing Modflow 4 v E Dispersion Chemical Reaction MOC3D Iv Simulate Dispersion First order decay rate 1 ny 0 Effective molecular diffusion coefficient 2 71 0 Longitudinal Manaus HERE dispersivity L 10 2 1 To set Strong Weak Flag Choose MOC3D Strong Weak Flag from the Models menu Move the grid cursor to the cell 25 15 1 Press the right mouse button and type 1 then click OK Note that a strong sink or source is indicated by the value of 1 in the matrix When a fluid source 1s strong new particles are added to replace old particles as they are advected out of that cell Where a fluid sink 1s strong particles are removed after they enter that cell Repeat steps 2 and 3 to assign the value 1 to the cells 25 15 2 and 25 15 3 Choose Leave Editor from the File menu or click the leave editor button ipe To specify the output terms and times Choose MOC3D Output Control from the Models menu An Output Control MOC3D dialog box appears The options in the dialog box are grouped under five tabs Concentration Velocity Particle Locations Disp Coeff and Misc In the Concentration tab
151. T AAA IRURE AAA e ARAM 13 lt 8000 feet Fig 6 26 Configuration of the model and the location of the observation well Modeling Approach and Simulation Results The aquifer 1s simulated using one model layer Specification of the elevations of layer top and bottom are not necessary because the layer 1s confined and transmissivity and confined storage coefficient are specified directly as defined in the Layer Options dialog box The sinusoidal distribution of the recharge rate was divided into 15 day intervals for the model simulation and the rate for the middle of each interval was used as input value The distribution used in the simulation 1s also shown in Fig 6 27 A total of six 360 day infiltration periods 144 stress periods each with a length of 15 days was used in the simulation The first five 360 day infiltration periods were computed to allow the model to reach a stable yearly cycle because the starting water level for each model cell was not known Results of the model simulation from the sixth infiltration period are compared to the results from the analytical solution for an observation well 2 000 ft from the river Fig 6 28 The coordinates of the observation well are given in the Boreholes and Observations dialog box The Streamflow Routing package is not really needed to simulate this condition as the river could have been represented using fixed head or river cells The same results can be obtained using the River
152. T and tune the optimization algorithm to the problem at hand The items of the control data are described in detail below When in doubt you should use the default values given by PMWIN RLAMBDALT is the initial Marquardt lambda PEST attempts parameter improvement using a number of different Marquardt lambdas during any one optimization iteration In the course of the overall parameter estimation process the Marquardt lambda generally gets smaller An initial value of 1 0 to 10 0 is appropriate for many models though if PEST complains that the normal matrix is not positive definite you will need to provide a higher initial Marquardt lambda For high values of the Marquardt parameter and hence of the Marquardt lambda the parameter estimation process approximates the gradient method of optimization While the latter method is inefficient and slow if used for the entire optimization process it often helps in getting the process started especially if initial parameter estimates are poor PEST reduces lambda if it can However if the normal matrix 1s not positive definite or if a reduction in lambda does not lower the objective function PEST has no choice but to increase lambda RLAMEFAC is the factor by which the Marquardt lambda is adjusted RLAMFAC must be greater than 1 0 When PEST reduces lambda it divides by RLAMFAC when it increases lambda it multiplies by RLAMFAC PHIRATSUF is the first criterion for moving to the next optimization
153. TER FILE NAME CR ENTER DATA INTERACTIVELY Help WHAT YOU SHOULD DO Just press ENTER here For the first time you run MODPATH or MODPATH PLOT you do not have a response file and you have to enter data interactively The user specified data will be saved by MODPATH or MODPATH PLOT in the response files MPATH RSP or MPLOT RSP respectively Using a response file you do not need to go through the input procedures unless you want to change the data for MODPATH or MODPATH PLOT Only for MODPATH PLOT TO REDEFINE SETTINGS ENTER NAME OF FILE WITH SETTINGS DATA lt CR gt USE DEFAULT SETTINGS FOR DEVICE Help WHAT YOU SHOULD DO Just press ENTER here unless you want to change settings ENTER THE NAME FILE Help WHAT YOU SHOULD DO Type pathMPATH30 at this prompt Where path is the path to the directory of your model data For example if you have saved your model data in C PMWIN DATA you will type C PMWIN DATA MPATHS0 at this prompt After this prompt you enter the interactive input procedure of MODPATH or MODPATH PLOT Just follow the prompts of the programs Appendix 5 Using PMWIN with your MODFLOW Processing Modflow 327 8 References Akima H 1978a A method of bivariate interpolation and smooth surface fitting for irregularly distributed data points ACM Transactions on Mathematical Software 4 148 159 Akima H 1978b Algorithm 526 Bivariate interpolation and smooth surface fit
154. The hydraulic conductivity is uniformly 3x10 m s The unconfined storage coefficient specific yield is 0 2 Recharge is assumed to be zero The groundwater flow is directed from west to east with a hydraulic gradient of 0 5 o To prevent contaminated water flow out of the area a remediation measure is required Different types and combinations of measures can be introduced for this purpose including a cut off wall around the area drainages and pumping wells All measures are directed towards the same goal a reduction of the piezometric head in the contaminated area itself such that groundwater flows towards the contaminated area To achieve this objective a cut off wall around this area and four pumping wells have been chosen The cut off wall 15 0 5 m thick and the hydraulic conductivity of the material is 5x10 m s Your task 1s to estimate the required pumping rate of the wells such that the steady state piezometric head in the center of the contaminated area 1s 8 m Furthermore the duration until the steady state 1s reached should be calculated Modeling Approach and Simulation Results The aquifer 15 simulated using a grid of one layer 31 columns and 31 rows The layer type 15 1 unconfined Fig 6 36 shows the model grid and the selected boundary conditions The extent of the model is fairly large To obtain the hydraulic gradient of 0 5 o the west and east sides of the model are assumed to be fixed head boundaries with hydraulic heads
155. These tabs are described below Files PMWIN Model If you have already opened a model within PMWIN and started the Field Interpolator from the Tools menu this field contains the model file name If Open Field Interpolator L xi Files Grid Position Search Gridding Method PMWIN Model c pmwin examples pmex pm5_1 example pm5 r Input File c pmwin examples pmex pm5_1 measure dat r Fig 5 1 The Field Interpolator dialog box a model first is shown you must click and select an PMWIN model from a standard Open File dialog box A PMWIN model file always has the extension PMS Input File An input file contains the measurement data and can be prepared with the Digitizer or other software Click to select an existing input file An input file must be saved in ASCII and have the following format 5 dus Z Yo Z5 7 Yn Zy first line of the file N is the number of data points second line of the file third line of the file i 1 th line of the file last line of the file 5 2 The Field Interpolator 202 Processing Modflow Where is the number of data points X and y are the x and y coordinates of data point i and f is the measurement value at data point i The maximum number of data points is 2000 Output file An output file contains the interpolated data for each model cell and is saved in the ASCII matrix format See Appendix 2 for the format of the ASCII matri
156. WIN is installed for example C Program Files PM5 The memory allocation of the so called X array is fixed in MODFLOW 96 This means the maximum number of cells is limited at a certain level when you use MODFLOW 6 Use the versions of PMWIN 4 X if you have a large model Note that the corresponding source code of these programs except the density package can be found in the Source folder of the distribution CD Table 3 5 Model data checked by PMWIN Term Checking Criteria layer thickness top and bottom elevation of layers initial head at fixed head cells Horizontal hydraulic conductivity transmissivity vertical hydraulic conductivity vertical leakance or effective porosity Storage coefficient specific storage or specific yield Hiver package Drain package General head boundary otreamflow Routing package Well package 3 6 MODFLOW may not be zero or negative consistency of the elevations a fixed head cell may not be dry at the beginning of a simulation may not be zero or negative may not be negative 1 a river cell may not be a fixed head cell and should not be an inactive cell 2 elevation of the riverbed should be higher than the elevation of the cell bottom 3 the river stage must be higher than elevation of the riverbed 1 a drain cell may not be a fixed head cell and should not be an inactive cell 2 elevation of the drain should be higher than the elevation of t
157. X Y Explanation of Fields Used in Input Instructions ALL DATA IN THE SAME RECORD ARE SEPARATED BY A COMMA OR BLANK NVERTEX is the number of vertices of a polyline X is the x coordinate of the i th vertex is the y coordinate of the i th vertex Observation File An observation file can be created by the Boreholes and Observations dialog box see section 3 5 or the Graphs Viewer see section 5 6 An existing observation file can be imported into the Boreholes and Observations dialog box File Format 1 Data LABEL 2 Data NOBS XXX XXX XXX XXX The following data repeats NOBS times 3 Data TIME WEIGHT HEAD DDOWN CONC COMPAC PREHEAD SUBSDNS NAME Explanation of Fields Used in Input Instructions ALL DATA IN THE SAME RECORD ARE SEPARATED BY A COMMA OR BLANK LABEL is the file label It must be PMWIN5000 OBS FILE NOBS is the number of observations Maximum number of NOBS is 10000 XXX reserved BORENO is the borehole number where the observation is made TIME is the observation time measured from the start of the simulation WEIGHT is the weight attached to each observation HEAD is the observed head at time TIME DDOWN is the observed drawdown at time TIME CONC is the observed concentration at time TIME COMPAC isthe compaction at time TIME PREHEAD is the preconsolidation head at time TIME SUBSDNS is the subsidence at time TIME NAME is the name of the borehole at which the observations are made Time Parameter File
158. a value to a digitized point Click the Digitize button Move the mouse cursor to a point 3 Press the right mouse button once The Digitizer shows a dialog box 4 In the dialog box type a new value then click OK 5 2 The Field Interpolator Numerical groundwater models require areally distributed parameters e g hydraulic conductivity hydraulic heads elevations of geological layers etc assigned to each cell or element in the model domain Usually the modeler obtains a parameter distribution in the form of scattered irregular data points x y f 1 1 N N is the number of measurement points x and y are the coordinates and f is the parameter value at point 1 A basic problem is how to estimate the parameter values for each model cell from these data A number of interpolation or extrapolation methods for solving this kind of problems have been proposed Some of the methods are used by commercial contouring software e g GEOKRIG GRIDZO SURFER or TECKON A common approach done by many modeler is that contour maps are firstly created by these software then overlaid on the model grid for assigning parameter values to model cells The process is indirect and somewhat cumbersome The Field Interpolator provides a more direct way for assigning cell values by using the Kriging method and methods developed by Shepard 1968 Akima 1978a 1978b and Renka 1984a 1984b The interpolation programs take measurement data and interpola
159. ach frame 5 Select a species from Species Number if the result type is Concentration MT3DMS In the Animation dialog box click OK to start the animation PMWIN will create a frame image for each time point at which the simulation results have been saved When all frames are created PMWIN will repeat the animation indefinitely until the Esc key is pressed 3 3 The File Menu Processing Modflow 69 3 4 The Grid Menu Mesh Size Allows you to generate or modify a model grid See Section 3 1 for how to use the Grid Editor Layer Type Select Layer Type to open the Layer Options dialog box Fig 3 14 The elements of this dialog box are described below gt Type The numerical formulations which are used by the Block Centered Flow BCF package to describe groundwater flow depend on the type of each model layer The layer types are TypeO layer is strictly confined For transient simulations the confined storage coefficient specific storage x layer thickness is used to calculate the rate of change in storage Transmissivity of each cell is constant throughout the simulation Type 1 layer is strictly unconfined The option is valid for the first layer only Specific yield is used to calculate the rate of change in storage for this layer type During a flow simulation transmissivity of each cell varies with the saturated thickness of the aquifer Type2 layer of this type is partially convertible between con
160. ady state flow simulation with only one stress period and one time step the stress period and time step number should be 1 4 Click Read Hydraulic heads in the first layer at time step 1 and stress period 1 will be read and put into the spreadsheet You can scroll the spreadsheet by clicking on the scrolling bars next to the spreadsheet 5 Click Save A Save Matrix As dialog box appears By setting the Save as type option the result can be optionally saved as an ASCII matrix or a SURFER data file Specify the file name H1 DAT and select a folder in which H1 DAT should be saved Click OK when ready 6 Repeat steps 3 4 and 5 to save the hydraulic heads of the second and third layer in the files H2 DAT and H3 DAT respectively 7 Click Close to close the dialog box 2 Run a Steady State Flow Simulation 24 Processing Modflow To generate contour maps of the calculated heads Choose Presentation from the Tools menu Data specified in Presentation will not be used by any parts of PMWIN We can use Presentation to save temporary data or to display simulation results graphically Choose Matrix from the Value menu or Press Ctrl B The Browse Matrix dialog box appears Fig 2 10 Each cell of the spreadsheet corresponds to a model cell in the current layer You can load an ASCII Matrix file into the spreadsheet or save the spreadsheet in an ASCII Matrix file by clicking Load or Save Alternatively you may select the Results Extract
161. ald et al 1991 In an aquifer system where two aquifers are separated by a confining bed large pumpage withdrawals from the bottom aquifer can desaturate parts of the upper aquifer If pumpage is discontinued resaturation of the upper aquifer can occur Fig 6 21 shows two aquifers separated by a confining unit No flow boundaries surround the system on all sides except that the lower aquifer discharges to a stream along the right side of the area Recharge from precipitation 1s applied evenly over the entire area The stream penetrates the lower aquifer in the region above the stream the upper aquifer and confining unit are missing Under natural conditions recharge flows through the system to the stream Under stressed conditions two wells withdraw water from the lower aquifer If enough water 15 pumped cells in the upper aquifer will desaturate Removal of the stresses will then cause the desaturated areas to resaturate Your task 1s to construct a model to compute the natural steady state head distribution and then calculate the head distribution under the stressed condition When solving for natural conditions the top aquifer initially 1s specified as being entirely dry and many cells must convert to wet When solving for pumping condition the top aquifer is initially specified to be under natural conditions and many cells must convert to dry Modeling Approach and Simulation Results The model consists of two layers one for each aq
162. alent hydraulic conductivity describing all of the head loss between the drain and the aquifer It depends on the material and characteristics of the drain itself and the immediate environment The value C is usually unknown and must be adjusted during a model calibration MODFLOW Evapotranspiration The Evapotranspiration package simulates the effects of plant transpiration and direct evaporation in removing water from the saturated groundwater regime Evapotranspiration 1s defined by assigning the following data to each vertical column of cells in the Evapotranspiration Package dialog box Fig 3 17 of the Data Editor Maximum ET Rate Reg LT Elevation of the ET Surface h L ET Extinction Depth d L Layer Indicator I and Parameter Number The specified values are shown from left to right on the status bar These values are constant during a given stress period For transient flow simulations involving several stress periods these values can be different from period to period Note that although the values are specified for each vertical column of cells you may move to other layers within the Data Editor and examine the grid configuration in each layer The parameter number is used to assign Heg as a parameter for 3 6 1 MODFLOW 82 Processing Modflow an automatic calibration by the inverse models PEST see PEST gt Parameter List or UCODE Parameter List Maximum ET Rat
163. alog box enter Recharge Flux L T 0 0 Layer Indicator IRCH J 0 Recharge Options Recharge is applied to the highest active cell Click OK to exit the dialog box 5 Leave the Data Editor by File Leave Editor which brings up the Temporal Data dialog box Select Period 2 and click on Edit Data to edit the data for that period Using the above procedure change the recharge flux for the entire grid to 0 00075 the values for the layer indicator and recharge option remain the same 8 Exit the Data Editor by File Leave Editor which again brings up the Temporal Data dialog box 9 Exit the Temporal Data dialog box and the Data Editor by Leave Editor Yes opecific Yield Before running the transient simulation it 1s necessary to set the aquifer specific yield to 0 06 gt specify the specific yield 1 Select Parameters gt Specific Yield 2 Setthe entire grid to 0 06 and exit the Data Editor by File Leave Editor Yes Run transient flow simulation gt To run the flow simulation 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge 230 Processing Modflow Select Models gt MODFLOW Run 2 Click OK to accept the warning regarding the Effective Porosity in the Processing Modlflow dialog box 3 Click OK in the Run Modflow dialog box to generate the required data files and to run MODFLOW you will see a DOS window open and MODFLOW perform the iterations required to complete the flow simulation 4
164. alue of this relative change must be less than RELPARMA X If a parameter upgrade vector is calculated such that the relative adjustment for one or more 3 55 relative limited parameters 1s greater than RELPARMA X the magnitude of the upgrade vector is reduced such that this no longer occurs If parameter b is factor limited the factor change between optimization iterations i 1 and 1 15 defined as b 4 6 if b gt b or 3 56 b b If b gt b This factor change must be less than FACPARMA X If a parameter upgrade vector is calculated such that the factor adjustment for one or more factor limited parameters is greater than FACPARMA X the magnitude of the upgrade vector is reduced such that this no longer occurs It is important to note that a factor limit will not allow a parameter to change sign If a parameter must be free to change sign during an optimization process it must be relative limited furthermore RELPARMA X must be set at greater than unity or the change of sign will be impossible Similarly if a parameter s upper or lower limit is Zero it cannot be factor limited and RELPARMA X must be at least unity Suitable values for RELPARMA X and FACPARMA X can vary enormously from case to case If you are unsure of how to set these parameters a value of 5 for each of them is often suitable For highly non linear problems these values are best set low If they are set too low however the estimation process can be
165. an the initial hydraulic head the value of the preconsolidation head will be set to that of the initial hydraulic head Elastic Storage Factor for interbeds present in the model layer Inelastic Storage Factor S for interbeds present in the model layer Starting Compaction L Compaction values computed by the Interbed Storage package are added to the starting compaction so that stored values of compaction and land subsidence may include previous components The starting compaction does not affect calculations of storage changes or resulting compaction and 3 6 MODFLOW 86 Processing Modflow Parameter Number The parameter number is used to assign S as a parameter for an automatic calibration by the inverse models PEST or UCODE see PEST Parameter List or UCODE Parameter List For a confined aquifer elastic compaction or expansion of sediments is proportional or nearly proportional to change in hydraulic head in the aquifer The following equation is used to calculate the change in the thickness Ab L of the interbed positive for compaction and negative for expansion Ab Ah S by Ah S 3 10 where Ah L is change in hydraulic head positive for increase S 1 is the skeletal component of elastic specific storage 0 is the thickness of the interbed and S is the user specified elastic storage factor When compressible fine grained sediments are stressed beyond a previous maximum
166. analytical and numerical solutions EI porri cms cm qnn dran puc cm enc cmt cm rcm pe gee og m vm em dispersivity 4 ee a Se oe Se ee ol LE HLb k kLh l 1 1 2 simulation time days Fig 6 58 Comparison of the calculated breakthrough curves with different dispersivity values 6 6 1 One Dimensional Dispersive Transport Processing Modflow 297 6 6 2 Two Dimensional Transport in a Uniform Flow Field Folder pm5 examples transport transport2 Overview of the Problem In this example transport of solute injected continuously from a point source in a steady state uniform flow field should be simulated The available parameters are listed below Layer thickness 10 Groundwater velocity 1 3 m day Effective porosity 0 3 Longitudinal dispersivity 10 m Ratio of transverse to longitudinal dispersivity 0 3 Volumetric injection rate 1 m day Concentration of the injected water 1000 ppm Your task is to construct a 2D model and use MT3DMS to calculate the concentration distribution at the end of a 365 day simulation period Modeling Approach and Simulation Results A numerical model consisting of 46 columns 31 rows and 1 layer was constructed to simulate the problem A regular grid spacing of 10 m is used for each column and row
167. and the correlation coefficient matrix Calibration result from PEST Parameter Estimated 95 percent confidence limits value lower limit upper limit pl L20002928E 02 9 12499 LE 03 1 029859E 02 1 9965080E 09 L9995901E 09 2 0065 8E 08 Note confidence limits provide only an indication of parameter uncertainty They rely on a linearity assumption which may not extend as far in parameter space as the confidence limits themselves see PEST manual Correlation Coefficient Matrix gt TU 0 9572 2512 Ta OWO 6 4 1 Basic Model Calibration Skill with PEST UCODE Processing Modflow 273 Table 6 5 Optimized parameter values and the correlation coefficient matrix Calibration result from UCODE PARAMETER ID UPPER 95 C I 1 FINAL VALUES 1 00k LOWER 95 C I 9r 00m CORRELATION MAT 2 1 1 000 0 9869 2 0 9869 1 000 PA 02 02 03 P2 2 2 0 R0 2 0E 09 1 98E 08 6 4 1 Basic Model Calibration Skill with PEST UCODE 274 Processing Modflow 6 4 2 Estimation of Pumping Rates Folder pm5 examples calibration calibration2 Overview of the Problem This example involves the encapsulation of a highly contaminated area The aquifer in which the contaminated area is buried is unconfined isotropic and of infinite areal extent The extent of the contamination area is about 65 m x 65 m The head in the center of this area is about 9 45 m The elevation of the aquifer top is 10 m and the aquifer bottom is at 0 m
168. arameter numbers associated with storage coefficient Parameter numbers associated with specific yield Description Wetting threshold Wetting threshold Description Cell density Zone file Description Hydraulic conductance of the interface between an aquifer and a drain Elevation of drain Parameter numbers associated with drains Zone file Evapotranspiration Package Extension Type Description EET CBC Maximum evapotranspiration rate L T EIE CBC Layer indicator array For each horizontal location it indicates the layer from which evapotranspiration is removed ESU CBC Elevation of the evapotranspiration surface EXD CBC Evapotranspiration extinction depth 292 CBC Parameter numbers associated with EVP cells ETZ ZONE Zone file General Head Boundary Package Extension Type GHB CBC GHC CBC 293 CBC GCZ ZONE Description Head on the general head boundary Hydraulic conductance of the interface between the aquifer cell and the general head boundary Parameter numbers associated with GHB cells Zone file Appendix 4 Internal Data Files of PMWIN 320 Processing Modflow Horizontal Flow Barriers Package Extension Type Description WAL CBC Direction of a horizontal flow barrier WAC CBC Hydraulic conductivity divided by the thickness of a horizontal flow barrier Interbed Storage Package Extension Type Description IB1 CBC Preconsolidation Head IB2 CBC Elastic Storage Factor IB3 CBC Inelastic Stora
169. are placed around or on the cell faces of each pumping well Through backward tracking capture zones of each pumping well can be recognized by their different colors Run particles backward Click this button to execute backward particle tracking for a specified time length The time length is the product of the number of particle tracking steps and the particle tracking step length given in the Particle Tracking Time Properties dialog box See sec 4 3 for details Run particles backward step by step Click this button to move particles backward a single particle tracking step The particle tracking step length 15 defined in the Particle Tracking Time Properties dialog box See sec 4 3 for details Stop You can click the Stop button to stop particle tracking or stop redrawing particles when the Stop button is highlighted ie the rectangle on the button is colored in red PMPATH redraws the particles whenever the PMPATH window has been covered by other windows and becomes visible again For example if you change to another application and then return to PMPATH PMPATH will redraw all particles If too many particles are placed you will need to keep PMPATH from redrawing all particles Under some circumstances PMPATH will take a long time for calculating the coordinates of flow paths and travel times This 1s especially true if the flow velocities and the user specified time step length of particle tracking are very 4 2 PMPATH
170. as a subregion Select an option from the Options group Just before a loaded matrix is put to the spreadsheet its values will be modified according to the following options Replace The cell data in the spreadsheet are replaced by those of the ASCII Matrix Add The cell values of the ASCII Matrix are added to those of the spreadsheet Subtract The cell data in the spreadsheet are subtracted from those of the loaded matrix Multiply The cell data in the spreadsheet are multiplied by those of the loaded matrix Divide The cell data in the spreadsheet are divided by those of the loaded matrix If a cell value of the loaded matrix 1s equal to zero the corresponding cell value in the spreadsheet remains unchanged Load Matrix File C PMSDATA e_matrix dat Start Position Options Column J Row 1 Replace Add Cancel C Subtract lu Maximum Numbers n Column 30 Row 30 C Multiply Help C Divide Fig 3 59 The Load Matrix dialog box Notes 1 Because of the nature of SURFER a SURFER GRD file may only be used with regularly spaced model grids Consider to use the Field Interpolator see Chapter 5 if your model grid is irregularly spaced PMWIN only accepts SURFER GRD files which are saved in ASCII 3 8 The Value Menu Processing Modflow 163 I L H finite difference arid Fig 3 60 The starting position of a loaded ASCII matrix Rese
171. ase flow at western model boundary 10 cfs river base flow at eastern model boundary 11 125 cfs riverbed conductance 0 01 ft s 6 4 1 Basic Model Calibration Skill with PEST UCODE Processing Modflow 271 Eee LII SSi itt tt ENBENNERNSE MES HERS BEE PT CN eee ae Eee CERE tt og ie NEN See Fig 6 35 Configuration of the aquifer system Table 6 2 River data Row Column Stage ft Riverbed Elevation ft 4 1 100 0 90 0 4 100 0 90 0 4 3 100 0 90 0 4 4 99 0 89 0 4 5 99 0 89 0 5 6 98 0 88 0 6 7 97 0 86 0 7 8 96 0 86 0 8 9 95 0 85 0 9 10 94 0 84 0 9 11 94 0 84 0 9 12 94 0 84 0 9 13 94 0 84 0 9 14 93 0 83 0 9 15 93 0 83 0 Table 6 3 Measurement data Bore Row Column Head ft 1 14 1 124 0 2 11 4 119 9 3 13 13 113 9 4 8 1 116 1 5 4 12 113 0 6 9 6 114 0 7 2 3 108 5 8 11 10 111 7 9 7 14 107 6 10 3 18 111 3 11 2 15 115 6 6 4 1 Basic Model Calibration Skill with PEST UCODE 212 Processing Modflow Modeling Approach and Simulation Results The aquifer 1s simulated using a grid of one layer 15 columns and 15 rows A regular grid space of 500 ft is used for each column and row The layer type is 0 confined and the Transmissivity flag in the Layer Options dialog box is user specified Transmissivity and recharge are defined as estimated parameters with the parameter numbers 1 and 2 Note that the names of t
172. ata Editor Button Action Leave the Data Editor assign value Allows you to move the grid cursor and assign values zoom in Allows you to drag a zoom window over a part of the model domain amp e el e E zoom out Displays the entire worksheet Cell by cell input method Switch to the cell by cell input method ri Zone input method Switch to the zone input method local display mode Switch to the local display mode real world display mode Switch to the real world display mode an duplication on off If duplication is turned on the cell value s of the current cell will be copied to all cells passed by the grid cursor Duplication is on when the relief of the button is sunk layer copy on off If you turn layer copy on and then move to another layer the zones and cell values of the current layer will be copied Layer copy is on when the relief of the button is sunk 3 2 The Data Editor 60 Processing Modflow i Processing Modflow EXPMDIS PM5 File Value Options Help Eie aene ae current layer grid cursor mouse cursor position of the mouse cursor in real world x y coordinates position of the grid cursor in cell indices J I KJ 0001 0 value s associated with the cell J I K Fig 3 5 The Data Editor local display mode Processing Modflow EXPMDIS PM5 File value Options Help 8 je ser Worksheet 67784 71 5184
173. ate gt the flow simulation 1 Select Models gt MODFLOW gt Run 2 Click OK to accept the warning regarding the Effective Porosity in the Processing Modflow dialog box 3 Click OK in the Run Modflow dialog box to generate the required data files and to run MODFLOW you will see a DOS window open and MODFLOW perform the iterations required to complete the flow simulation 4 Press any key to exit the DOS Window 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge Processing Modflow 223 Step 6 Extract and view results from the steady state flow simulation It is now time to view the results of your efforts but first it is necessary to understand how the Results Extractor operates On occasions it 1s necessary to view some of the various sorts of output such as hydraulic heads and cell by cell flows generated by a MODFLOW simulation This 2D data is accessed using the Results Extractor and saved in ASCII format on the computer s hard drive for use in other parts of PMWIN or in other programs such as SURFER or a spreadsheet program It is quite a simple procedure to load and save any of the output generated by MODFLOW and in fact is a necessary first step in producing any form of graphical output from your MODFLOW simulations The data files saved in the Results Extractor can be read back into the model using the Data Editor this procedure will be explained shortly gt To load the head distribution after the
174. ate all input files for MT3D Generate inputfiles only don t start MT3D Cancel Help Fig 3 47 The Run MT3D MT3D96 dialog box 3 6 3 MT3D 132 Processing Modflow 3 6 4 MT3DMS As MT3DMS retains the same modular structure of the MT3D code the interface implemented in PMWIN is very similar to the MT3D interface One of the major differences is that you are asked to specify initial concentration source concentration and parameters for chemical reactions for each active species in the Data Editor Before switching to the Data Editor PMWIN will display a dialog box which allows you to manage the data of each species For example if you select MT3DMS Initial Concentration the Initial Concentration MT3DMS dialog box Fig 3 48 will appear You have the following options 1 Edit the initial concentration data for a species by selecting a row from the table and clicking the Edit button After specifying and saving the data the Active and Data flags will be checked You may click on an Active flag to activate or deactivate a species The Data flag offers three status configuration possibilities E data has been specified and will be used for simulation data has been specified but will not be used the default value of zero will be used O data is not available the flag is dimmed and deactivated Once the data 1s specified you may click on a Data flag to check or uncheck it Initial Concentration kMT3DMS
175. ated area This value is the concentration associated with the recharge flux Since the recharge rate is 8 x 10 m m s and the dissolution rate is 1 x 10 ug s m the concentration associated with the recharge flux is 1 x 10 8 x 10 12500 ug m Choose Leave Editor from the File menu or click the leave editor button ge To assign the parameters for the advective transport Choose MOC3D Advection from the Models menu A Parameters for Advection Transport MOC3D dialog box appears Enter the values as shown in Fig 2 30 into the dialog box select Bilinear X Y directions for the interpolation scheme for particle velocity As noted by Konikow et al 1996 if transmissivity within a layer 15 homogeneous or smoothly varying bilinear interpolation of velocity yields more realistic pathlines for a given discretization than does linear interpolation Click OK to close the dialog box Parameters for Advective Transport MOC3D Interpolation scheme for particle velocity Maximum number of particles NPMAX 50000 Courant number CELDIS 75 Fraction limit for regenerating initial particles FZERO De Initial number of particles per cell NPTPND 8 PNEWL PNEWR PNEWC Fig 2 30 The Parameters for Advective Transport dialog box To assign the parameters for dispersion and chemical reaction Choose MOC3D Dispersion amp Chemical Reaction from the Models menu A Dispersion Chemical
176. ated to all cells passed over by the grid cursor if duplication is on Move the grid cursor from the upper left cell to the lower left cell of the model grid The value of 9 is duplicated to all cells on the west side of the model Turn on layer copy by clicking the layer copy button Layer copy is on if the relief of the layer copy button is sunk The cell values of the current layer will be copied to another layer if you move to the other model layer while layer copy is on Move to the second layer and the third layer by pressing PgDn twice The cell values of the first layer are copied to the second and third layers Choose Leave Editor from the File menu or click the leave editor button ge To specify the horizontal hydraulic conductivity Choose Horizontal Hydraulic Conductivity from the Parameters menu Choose Reset Matrix from the Value menu or press Ctrl R type 0 0001 in the dialog box then click OK Move to the second layer by pressing PgDn Choose Reset Matrix from the Value menu or press Ctrl R type 0 0005 in the dialog box then click OK Repeat steps 3 and 4 to set the value of the third layer to 0 0005 Choose Leave Editor from the File menu or click the leave editor button e To specify the vertical hydraulic conductivity Choose Vertical Hydraulic Conductivity from the Parameters menu Choose Reset Matrix from the Value menu or press Ctrl R type 0 00001 in the dialog box then click OK Move
177. athematical models 228 pp American Geophysical Union Jorggensen D G 1980 Relationship between basic soils engineering equations and basic ground water flow equations U S Geological Survey Water Supply Paper 2064 Kinzelbach W 1986 Groundwater Modelling An introduction with sample programs in BASIC Elsevier ISBN 0 444 42582 9 Kinzelbach W P Ackerer C Kauffmann B Kohane and B Moller 1990 FINEM Numerische Modellierung des zweidimensionalen Stromungs und Transportproblems mit Hilfe der Methode der finiten Elemente Programmdokumentation Nr 89 23 HG 111 Institut f r Wasserbau Universitat Stuttgart Kinzelbach W M Marburger W H Chiang 1992 Determination of catchment areas in two and three spatial dimensions J Hydrol 134 221 246 Kinzelbach W R Rausch 1995 Grundwassermodellierung Einf rung mit bungen Borntraeger Berlin Stuttgart ISBN 3 443 01032 6 Konikow L and J D Bredehoeft 1978 Computer model of two dimensional solute transport and dispersion in ground water U S Geological Survey Water Resources Investigation Book 7 Chapter C2 90 pp 8 References Processing Modflow 331 Konikow L F D J Goode and G Z Homberger 1996 A three dimensional method of characteristics solute transport model U S Geological Survey Water Resources Investigations report 96 4267 Kuiper L K 1981 A comparison of the incomplete Cholesky conjugate gradient method with t
178. bject to some time dependent stresses It 1s usual to perform a steady state flow simulation first and use the resulting head distribution as the basis for the transient simulations which 1s what we shall do in this case v To set the initial hydraulic heads Select Parameters Initial Hydraulic Heads Firstly set the entire grid to a uniform value by Value Reset Matrix Enter 16 in the Reset Matrix dialog box and click OK to exit Now set hydraulic head of the northern fixed head boundary to 15 metres by first selecting A cx the top left cell 1 1 1 with the left mouse button and then assigning a value of 15 by clicking with the right mouse button and entering 15 in the Cell Value dialog box 5 Copy the value of 15 to the remainder of the northern boundary using the Duplication Button and the left mouse button 6 Leave the Data Editor by File Leave Editor Yes Time Parameters gt specify the time parameters Select Parameters gt Time 2 Inthe Time Parameters dialog box change the Simulation Time Unit to DAYS and check that Steady State is selected in the Simulation Flow Type box 3 Click OK to leave the Time Parameters dialog box Recharge rates v To specify the recharge rate Select Models gt MODFLOW Recharge Set the entire grid to a uniform value by Value gt Reset Matrix pure xs In the Reset Matrix dialog box enter 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharg
179. box The map is displayed in the Maps Options dialog box Fig 3 71 You can increase or decrease the magnification level of the display To zoom in hold down the Shift key and click the image with the left mouse button To zoom out hold down the Ctrl key and click the image with the right mouse button To display entire map hold down the Alt key and left click the image To move a part of the image to the center of the display simply left click the desired position gt To set geo reference points 1 Click the Set button from the Point 1 or Point 2 group The mouse cursor turns into a crosshairs 2 Place the crosshairs at a point with known x y real world coordinates and press the left mouse button 3 Enter the x y coordinates into the corresponding edit fields of the group Point 1 or Point 2 3 9 The Options Menu Processing Modflow 173 4 Repeat the steps 1 to 3 to set the other reference point Note that the geo reference points must not lie on a vertical or horizontal line e g the x and y coordinates of the points must not be the same Maps Options Vector Graphics Raster Graphics Filename e image2 bmp _ WE 1 Point 2 Raster x E 200 Iv Graphic Visible 20 200 Fig 3 71 Importing a geo referenced raster map 3 9 The Options Menu 174 Processing Modflow FOR YOUR NOTES 3 9 The Options Menu Processing Modflow 175 4 The Advective Transport
180. c Modeling Processing Modflow 307 mean safety criterion is the sum of safety criteria divided by the number of realizations A large number of realizations may be required for the mean safety criterion to converge vfum zoundury 8 m congzant head bou dary h c flow boundary Cree hd zoundary 7 8m rensar head 5 nust n boundary 8 rl h senstan eac boundary nu fhow seared M omn 8 m contaminated VM M 3 T x4 bheunday H constant ecd bounda h toris c flow bouaza gt t D T a T Z 1 E lt h Flow bou icu y Fig 6 68 Calculation of the mean safety criterion by the Monte Carlo method Realization 1 oafety Criterion 7 85 96 Mean Safety Criterion 85 Realization 2 safety Criterion 87 Mean Safety Criterion 86 Realization 3 Safety Criterion 97 Mean Safety Criterion 89 7 Realization 4 Safety Criterion 48 Mean Safety Criterion 79 3 Realization 5 Safety Criterion 93 Mean Safety Criterion 82 6 7 2 An Example of Stochastic Modeling 308 Processing Modflow FOR YOUR NOTES 6 7 2 An Example of Stochastic Modeling Processing Modflow 309 7 Appendices Appendix 1 Limitation of PMWIN This section gives the size limitation of PMWIN Refer to the documentation of individual packages f
181. cal leakance VCONT 3 4 The Grid Menu Processing Modflow 71 2 Av AV 9 1 UG Kajik where K and ik respectively While the ratio of horizontal to vertical hydraulic conductivity ranging from 1 1 to 1000 1 1s common in model application Anderson and Woessner 1992 A summary of hydraulic jare the vertical hydraulic conductivities of layers k and k l conductivity values of different materials can be found in Spitz and Moreno 1996 It is common in applications of MODFLOW to represent the resistance to flow in a low hydraulic conductivity unit see Fig 3 15b semiconfining unit by lumping the vertical hydraulic conductivity and thickness of the confining unit into a vertical leakance term between the adjacent layers These kinds of models are often called guasi three dimensional models because semiconfining units are not explicitly included and simulated In this case you must manually calculate the VCONT values using eq 3 2 and enter them into the Data Editor VCONT Az 2AZ AZ 3 2 where K o and K are the vertical hydraulic conductivities of the upper layer Z 2 semiconfining unit and lower layer respectively Geohydrologic VA Upper laver Unit A AV i ii k semiconfining unit k 7 Geohydrologie FA VA Unit B PA C 21 7 Aa ee AV 4 p i i AZ e fuer Y 4 Fig 3 15 Grid configurations used for the calcu
182. calculation of the objective function during an automatic calibration process but it must not be negative Refer to the documentations of UCODE and PEST for the function of weights in the parameter estimation process Note that drawdown at a certain observation time is defined by Ny h where hy is the initial hydraulic head and h is the head at the observation time gt Save Load and Clear Click the Clear button to clear the observation or borehole table Using the buttons Save and Load you can save or load the contents of tables in or from a Borehole file or Observation file The format of these files is given in Appendix 2 Note that you can insert or delete a row ina table by pressing Ctrl Ins or Ctrl Del key In PMWIN the maximum number of Boreholes is 1000 The maximum number of Observations is 10000 Horizontal Hydraulic Conductivity and Transmissivity Horizontal hydraulic conductivity 1s the hydraulic conductivity along model rows It is multiplied by an anisotropy factor specified in the Layer Options dialog box to obtain the hydraulic conductivity along model columns Horizontal hydraulic conductivity is required for layers of type 1 or 3 Transmissivity is required for layers of type 0 and 2 Typical values and ranges of horizontal hydraulic conductivity for differenttypes of soils are given in many groundwater textbooks for example Freeze and Cherry 1979 Spitz and Moreno 1996 and Fetter 1994 PMWIN uses the horizon
183. candrett C 1989 Comparison of several iterative techniques in the solution of symmetric banded equations on a two pipe Cyber 205 Appl Math Comput 34 2 95 112 8 References Processing Modflow 333 Schaars F W and M W van Gerven 1997 Density package Simulation of density driven flow in MODFLOW KIWA report SWS 97 511 ISBN 90 74741 42 8 KIWA Research amp Consultancy Nieuwegein The Netherlands Sch fer D W Schafer and R Therrien 1997 TBC An efficient simulator for three dimensional groundwater flow multispecies transport reactions in porous formations Institut fir Umweltphysik Universitat Heidelberg Shepard D 1968 A two dimensional interpolation function for irregularly spaced data Proceedings 23rd ACM National Conference 517 524 Spitz K and J Moreno 1996 A practical guide to groundwater and solute transport modeling 461 pp John wiley amp Sons ISBN 0 471 13687 5 Stone H L 1968 Iterative solution of implicit approximations of multidimensional partial differential equations SIAM J Numer Anal 5 530 558 Sun N Z 1995 Mathematical modeling of groundwater pollution 377 pp Springer Travis C C 1978 Mathematical description of adsorption and transport of reactive solutes in soil A review of selected literature Oak Ridge Natl Lab ORNL 5403 Trescott P C und S P Larson 1977 Comparison of iterative methods of solving two dimensional groundwater flow equations
184. ce approximation 1s usually only appropriate for two dimensional areal flow models The flow velocity across the top face of a cell 1n the top model layer would be zero if the existing recharge is not assigned to the top face Consequently particles cannot be tracked backwards to the top face In PMPATH recharge may be treated as a distributed source or assigned to the top face or bottom face of a cell by selecting a corresponding option from the dialog box Recharge will be assigned to the top face and negative recharge will be assigned to the bottom face if the option Assign recharge to top and bottom cell faces is chosen Evapotranspiration The option is disabled if evapotranspiration 15 not used Similar to Recharge evapotranspiration can be assigned to top face of a cell or treated as a distributed sink 4 3 PMPATH Options Menu 194 Processing Modflow Maps The Maps Options dialog box Fig 4 12 allows to display up to 5 background DXF maps and 3 Line maps A DXF file contains detailed data describing numerous CAD entities An entity is aline or symbol placed on a drawing by the CAD system PMWIN supports the following entities LINE POLYLINE POINT ARC SOLID CIRCLE and TEXT The other entities will be ignored There is no size limit to the number of the acceptable entities A Line Map consists of a series of polylines Each polyline is defined by a header line and a series of coordinate pairs The header line only contains th
185. cient number of particles NPMIN can be set to 0 in relatively uniform flow fields and a number greater than zero in diverging converging flow fields Generally a value between zero and four is adequate gt NPMAX is the maximum number of particles allowed per cell If the number of particles in cell exceeds NPMA X particles are removed from that cell until NPMAX is met Generally NPMAX can be set to approximately twice NPH gt SRMULT is a multiplier for the particle number at source cells SRMULT 1 In most cases SRMULT 1 is sufficient However better results may be obtained by increasing SRMULT gt NLSINK is a flag indicating whether the random or fixed pattern is selected for initial placement of particles to approximate sink cells in the MMOC scheme The convention is the same as that for NPLANE It is generally adequate to set NLSINK equivalent to NPLANE gt NPSINK is the number of particles used to approximate sink cells in the MMOC scheme The convention is the same as that for NPH It is generally adequate to set NPSINK equivalent to NPLANE gt DCHMOC is the critical relative concentration gradient for controlling the selective use of either MOC or MMOC in the HMOC solution scheme The MOC solution is selected at cells where the relative cell concentration gradient DCCELL is greater than DCHMOC The MMOC solution is selected at cells where the relative cell concentration gradient DCCELL is lessr than or equal to DCHMOC
186. ckage is supported only if you select the MODFLOW version MODFLOW Density package from KIWA in the Run Modflow dialog box See MODFLOW Run for more about the versions of MODFLOW MODFLOW Drain A drain is defined by using the Data Editor to assign three values to a model cell Drain hydraulic conductance C LT Elevation of the Drain d L and Parameter Number The values C and d and the parameter number are shown from left to right on the status bar The parameter number is used to assign C as a parameter for an automatic calibration by the inverse 3 6 MODFLOW Processing Modflow 81 models PEST see PEST gt Parameter List gt Parameter List These values are constant during a given stress period For transient flow simulations involving several stress periods these values can be different from period to period When the hydraulic head h in a drain cell is greater than the drain elevation water flows into the drain and is removed from the groundwater model Discharge to the drain is zero when the hydraulic head is lower than or equal to the median drain elevation Recharge from the drain 15 always zero regardless of the hydraulic head in the aquifer Discharge rate to the drain Q is calculated by Q Ca A d 3 5 The value C of a drain cell is often given by C K L 3 6 where L is the length of the drain within a cell The value K is an equiv
187. conductivities than the middle unit Fig 6 24 There is a regional water table in which the head is below the bottom of the middle unit Natural recharge occurs over the entire area at a rate of 0 001 foot per day This recharge can percolate through the two upper units without the formation of a water table above the middle because the vertical hydraulic conductivity of this unit is 0 002 foot per day Recharge at a rate of 0 01 foot per day from a pond covering 6 acres 223225 will cause a perched ground water body to form in the top two units The total pond leakage 1s about 2 360 cubic feet per day 7466 8 m d The perched water table spreads out over an area much larger than the area covered by the pond This has an impact on the distribution of recharge to the lower unit Your task 1s to calculate the long term head distribution resulting from the pond recharge Modeling Approach and Simulation Results Because of the rectangular symmetry of the system there 1s no flow between quadrants Therefore only one quarter of the system must be simulated The problem is simulated using a erid of 50 rows 50 columns and 2 model layers A uniform grid spacing of 16 feet 1s used The recharge pond is in the upper left corner of the grid the quarter of the pond that is simulated occupies a square area that is 16 rows long and 16 columns wide The boundaries along row 1 and along column 1 are no flow boundaries as a result of the symmetry Model la
188. criterion 15 10 000 cubic feet the wetting threshold is 0 5 foot the wetting factor is 0 5 and the wetting iteration interval is 1 Fig 6 23 shows simulated water table heads along row 1 at several times during the transient simulation Steady state conditions were reached at the 44th time step of the transient simulation as indicated by storage flow terms being zero see the simulation listing file OUTPUT DAT 6 2 4 Simulation of a Water Table Mound resulting from Local Recharge 256 Processing Modflow Simulated Water Table E25 c Water table pridr to pond leakage pois See Distance from center of pond in feet Steady State 190 days 708 days 2630 days Fig 6 23 Simulated water table heads along row 1 beneath a leaking pond after 190 days 708 days 2630 days and steady state conditions after McDonald et al 1991 6 2 4 Simulation of a Water Table Mound resulting from Local Recharge Processing Modflow 257 6 2 5 Simulation of a Perched Water Table Folder pm5 examples basic basic5 Overview of the Problem This example is the third test problem of the BCF2 Package Contrasts in vertical hydraulic conductivity within the unsaturated zone can provide a mechanism for the formation of perched ground water tables The conceptual model is rectangular and consists of three geohydrologic units The upper and lower units have higher hydraulic
189. culated The nodal grid forms the framework of the numerical model Hydrostratigraphic units can be represented by one or more model layers The thicknesses of each model cell and the width of each column and row can be specified The locations of cells are described in terms of columns rows and layers PMWIN uses an index notation J I for locating the cells For example the cell located in the 2nd column 6th row and the first layer 1s denoted by 2 6 1 Columns J 1 23456789 10 PESKY 50000006060 LOS p e 7 ELIT _ WS V Layers Fig 3 1 Spatial discretization of an aquifer system and the cell indices To generate or modify a model grid choose Mesh Size from the Grid menu If a grid does not exist a Model Dimension dialog box Fig 3 2 will allow you to specify the number of layers and the numbers and the widths of columns and rows of the model grid After specifying these data 3 The Grid Editor 56 Processing Modflow and clicking the OK button the Grid Editor shows a worksheet with a plan view of the model Fig 3 3 Using the Environment Options dialog box see section 3 9 you can adjust the coordinate system the extent of the worksheet and the positon of the model grid to fit the real world coordinates of your study site By default the origin of the coordinate system 15 set at the lower left corner of the worksheet and the
190. d While a plume grows it will not only undergo the microscopic mechnical dispersion but also the dispersion caused by macroscopic heterogeneities This results to a trend of increasing dispersivity values with the scale of observation Summaries of the scale dependent dispersivity values are provided by Anderson 1979 1984 Gelhar et al 1985 1992 and Spitz and Moreno 1996 Note that all heterogeneity which 1s not explicitly represented in the model has to be incorporated into the dispersion coefficients gt Retardation factor For a linear isotherm the retardation factor is independent of the concentration field R is calculated by R 1 K 3 35 where n is the porosity of the porous medium Dispersion Chemical Reaction MOC3D Iv Simulate Dispersion First order decay rate 1 m 0 Effective molecular diffusion coefficient 2 71 0 TRUE Horizontal Longitudinal Layer ge transverse dispersivity L 10 1i 3 6 2 MOC3D 116 Processing Modflow MOC3D gt Strong Weak Flag A flag is required for each cell within the transport subgrid Where fluid source is strong new particles are added to replace old particles as they are advected out of that cell Where a fluid sink is strong particles are removed after they enter that cell and their effect has been accounted for Where sources or sinks are weak particles are neither added nor removed and the source sink e
191. d by using the filenames fn xxx where fn is the Frame File specified above and xxx 15 the serial number of the frame files Display Time is the display duration for each frame 5 Inthe Animation dialog box click OK to start the animation 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge Processing Modflow 231 PMWIN will create a frame image for each time point at which the simulation results here hydraulic head are saved When all frames are created PMWIN will repeat the animation indefinitely until the Esc key is pressed Once a sequence is created you can playback the animation at a later time by repeating the above steps with Create New Frames cleared You can also use the Animator provided by PMWIN to playback the sequence ee 6 09 5 ar EE ra a gt b E 1200 Wall 7 Well H We i cL Fig 6 5 Head distribution after 240 days of pumping period 1 time step 12 OSE 0878 7 peg Otay Well FG s Well 2 Well 3 D p y Well ON Well 4 Well 5 B E DT Wall 7 Wall H Well 8 E m E Fig 6 6 Head distribution after 120 days of recharge period 2 time step 6 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge 292 Processing Modflow 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River Folder pm5 examples tutorials tutorial2 Overview of the Problem A riv
192. d on one axis against the corresponding calculated values on the other If there is exact agreement between measurement and simulation all points lie on a 45 line The narrower the area of scatter around this line the better 1s the match gt create a scatter diagram for head values 1 Choose Graph gt Head Time from the Tools menu A Head Time Curves dialog box appears 2 Click the button Scatter Diagram PMWIN shows the scatter diagram Fig 2 39 See Chapter 5 for details about the use of this dialog box Scatter Diagram Comparison of Calculated and Observed Heads Save Plot As g Close Display simulation time s 5 D a Em 5 aq E 2 o e Use results from all simulation time s Use results from the C following simulation time 7 5 7 5 Observed Heads Variance 4 353224E 05 Fig 2 39 The Scatter Diagram dialog box 2 3 1 Perform Automatic Calibration with PEST Processing Modflow 49 2 3 2 Perform Automatic Calibration with UCODE gt specify the starting values for each parameter 1 Choose UCODE Parameter List from the Models menu A List of Calibration Parameters UCODE dialog box appears The options of the dialog box are grouped under five tabs Parameters Prior Information Control Data and Options 2 In the Parameters tab activate the first parameter by setting the Active flag to from Parameters table and e
193. d options for the PMWIN MODFLOW UCODE interface are specified in the List of Calibration Parameters UCODE dialog box Fig 3 55 The options are grouped under four tabs described below gt Parameters The table gives an overview of the initial values and properties of each estimated parameter The meaning of each column of the table is describen below Number While editing a certain aquifer property or excitation you have the option to define the extent of an estimated parameter by assigning a unique parameter number to the cells of interest That unique parameter number corresponds to the Number here Active The value of an estimated parameter will only be adjusted if Active is checked Otherwise the user specified cell value will be used for the simulation Normally the total number of active parameters should not exceed 10 although PMWIN allows 150 parameters Description A text describing the estimated parameter can be entered here optional for example Transmissivity in layer 3 A maximum of 120 characters is allowed Start value is a parameter s initial value Minimum and Maximum are the reasonable minimum and maximum values for the parameter The values are used solely to determine how the final optimized value of this parameter compares to a reasonable range of values Do not specify the log of log transformed parameters they are calculated by the program Log transform Check this flag to log transform the
194. d to change the settings in the Time group 2 Click Zones A zone is a subregion of a model for which a water budget will be calculated A zone 15 indicated by a zone number ranging from 0 to 50 A zone number must be assigned to each model cell The zone number 0 indicates that a cell 15 not associated with any zone Follow steps 3 to 5 to assign zone numbers 1 to the first and 2 to the second layer Choose Reset Matrix from the Value menu type 1 in the dialog box then click OK Press PgDn to move to the second layer Choose Reset Matrix from the Value menu type 2 in the dialog box then click OK Choose Leave Editor from the File menu or click the leave editor button Click OK in the Water Budget dialog box a SAN xs A di Water Budget Specify the stress period and time step far which the water budget should be calculated Click Zones to specify subregions When finished click OK to start the calculation Time Stress Period Time Step 1 Fig 2 8 The Water Budget dialog box PMWIN calculates and saves the flows in the file path WATERBDG DAT as shown in Table 2 3 The unit of the flows is L T Flows are calculated for each zone in each layer and each time step Flows are considered IN if they are entering a zone Flows between subregions are given in a Flow Matrix HORIZ EXCHANGE gives the flow rate horizontally across the boundary of a zone EXCHANGE UPPER gives the flow rate coming from IN or going to
195. decnce sweat an Sau i sapra rdv EIC II cree MAIN DAT MODPATH and MODPATH PLOT version 3 x data tile tat a tou Ohba ee Raed MAIN30 DAT Other files required by MODPATH such as RIV DAT or WEL DAT are the same as those of MODFLOW MOC3D MainMOCSD Package ont bathers oan E etes datore d onte Es MOCMAIN DAT Source Concentration in Recharge MOCCRCH DAT Observation Well PEU MET TA ETE IE ERE NE Te ER MET SR MOCOBS DAT MT3D AOVOCHIOT MTADV1 DAT PACKAGE esu de oer im sup be Sg Eq uoa a qup Sip da ure Da Goo dca pcd esa MTBTN1 DAT Chemical Reaction Package MTRCT1 DAT Dispersion Package scare edt ae bie DIET MTDSP1 DAT Sink amp Source Mixing MTSSM1 DAT MT3DMS Advection Package leer MTMSADV1 DAT Basic Transport Package 00 cece tee eee MTMSBTN1 DAT Chemical Reaction Package MTMSRCT1 DAT Appendix 3 Input Data Files of the supported Models Processing Modflow 317 DISDeISIORud c dci RP ue aa pi dr plate dou EC pei MTMSDSP1 DAT Generalized Conjugate Gradient Solver MSMSGSG
196. del domain and form part of the fine discretisation around some of the other wells 7 Repeat the above refinement around Well 2 to Well 9 remember some of the discretisation has already been done when you added rows and columns around Well 1 8 Atthis stage your cells increase from a size of 167 m to 500 m abruptly in order to have a more gradual increase in cell size we need to half the size of the following rows and columns again using the CTRL key and the arrow keys Columns 3 and 11 Rows 7 9 10 12 17 and 19 The number of the rows and columns are given in the status bar on the bottom of the screen and are numbered such that the cell specified by Column 1 Row 1 1s the top left cell of the model in a 3D sense the top layer is also Layer 1 with Layer numbers increasing with 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge Processing Modflow 219 depth Upon completion of the refinement your grid should look like that in Fig 6 2 9 Leave the Grid Editor by File Leave Editor Yes Eq operum s ees L E AER WE gp EE NER RU GR A RR ETE eRe eae eek esse Fig 6 2 Model discretization Step 4 Assign Model Data The Data Editor is accessed each time some spatial data such as recharge hydraulic conductivity etc need to be input to the model The format and commands of the Data Editor are the same for each parameter a
197. ding File Bun Options Help 2 11 TLLA a eer gorse MER TL LI i 7 Fig 4 1 PMPATH in operation The Advective Transport Model PMPATH 176 Processing Modflow The time length of a single particle tracking step and the maximum number of tracking steps can be specified Each particle can have its own color and retardation factor With these features PMPATH can be used to simulate advective transport in groundwater to delineate contaminant capture zones injection zones and wellhead protection areas or to find the point of origin of water in specified zones PMPATH creates several output files including hydraulic heads distribution velocity field the x y z coordinates and travel times of particles Graphics output includes DXF HPGL BMP Windows bitmap formats Due to PMPATH s intensive graphical capability there 1s no need for add
198. djustable parameters the initial parameter value PARV AL 1 must lie between these two bounds For fixed and tied parameters PARLBND and PARUBND are ignored PARTRANS controls the parameter transformation By clicking on a cell of the PARTRANS column this flag can be setas None Log transformed Tied or Fixed Use Log transformed if you wish that a parameter be log transformed throughout the 3 6 5 PEST Inverse Modeling Processing Modflow 143 estimation process A parameter which can become zero or negative in the course of the parameter estimation process must not be log transformed hence if a parameter s lower bound is zero or less PEST will disallow logarithmic transformation for that parameter Note that by using an appropriate scale and offset you can ensure that parameters never become negative Thus if you are estimating the value for a parameter whose domain as far as the model 15 concerned is the interval 9 99 10 you can shift this domain to 0 01 20 for PEST by designating a scale of 1 0 and an offset of 10 0 Similarly if a parameter s model domain 1s entirely negative you can make this domain entirely positive for PEST by supplying a scale of 1 0 and an offset of 0 0 See the discussion on the SCALE and OFFSET variables below If a parameter is fixed taking no part in the optimization process PARTRANS must be specified as Fixed If a parameter 1s linked to another parameter this is signified by a PARTRANS valu
199. e 10 The discharge from the aquifer 1s only to the river Transmissivity of the aquifer used for both the analytical solution and in the model simulation was 3 200 ft d 3 45x10 m s The storage coefficient is 0 20 Because the river is assumed to be fully penetrating and the aquifer 1s not separated from the river by any confining material the streambed conductance value was assumed equal to the transmissivity of the aquifer in this example the width of the river 1s assumed equal to the depth of the aquifer times the length of the river in each cell 1 000 ft divided by an assumed I foot thickness of the riverbed Actually any large streambed conductance value can be used as long as the head value in the model cell containing the river remains constant during the simulation Varying the streambed conductance value shows that for this problem streambed conductances greater than 10 ft d produce nearly the same results Annual recharge to the aquifer 1s 1 5 ft However the daily recharge rate varied according to a sinusoidal distribution for the first 180 days while no recharge was allowed for 6 2 6 Simulation of an Aquifer System with irregular Recharge and a Stream Processing Modflow 261 the following 180 days The distribution of the recharge over time 1s shown in Fig 6 27 columns 1 5 10 15 20 25 30 35 39 DADA VAI RITU Observation well DNE SUR OR o ARR EL
200. e 224 Processing Modflow Recharge Flux L T 0 00025 this is the mean recharge rate of the two seasons Layer Indicator IRCH 0 Recharge Options Recharge is applied to the highest active cell Click OK to exit the dialog box Leave the Data Editor by File Leave Editor Yes Specified Flux Boundary As MODFLOW does not have a separate package for specified flux boundary condition we use the Well package to simulate this boundary condition gt specify the boundary flux 1 Select Models gt MODFLOW Well 2 Make sure the cell selected is 1 36 1 Since the width of this cell 15 500 m the inflow rate throuth this cell is 500 m x 0 0672 m day m 33 6 m day Click the right mouse button to open the Cell Value dialog box and enter 33 6 then click OK to exit the dialog box A positive value means that water enters the system 3 Specify the value 33 6 to the cell 2 36 1 the value 16 8 to the cells 3 36 1 and 4 36 1 and the value 11 2 to the rest of the South boundary 4 Leave the Data Editor by File gt Leave Editor gt Yes Step 5 Perform steady state flow simulation You are just about ready to run the flow model Quickly review the data that you have entered for each of the parameters and checking the values of various cells Correct any data that do not look right by redoing the appropriate section above When checking any data entered under the Models menu item choose Edit rather than Deactiv
201. e L T Elevation ofthe ET Surface L 2 ET Extinction Depth L Layer Indicator IEVT Parameter Number D Evapotranspiration Options ET is calculated for cells in the top grid layer C Vertical distribution of evapotranspiration is specified in IEVT Current Position Column Row 18 11 he evapotranspiration option is applied to the entire matrix IEVT is only required if he second evapotranspiration option is selected Cancel Help Fig 3 17 The Evapotranspiration Package dialog box The Evapotranspiration package removes water from the saturated groundwater regime based on the following assumptions 1 When water table is at or above the elevation of the ET surface h evapotranspiration loss from the water table is at the maximum ET Rate Hey 2 Noevapotranspiration occurs when the depth of the water table below the elevation of the ET surface exceeds the ET extinction depth d and 3 In between these two extremes evapotranspiration varies linearly with the water table elevation These assumptions can be expressed in equation form as Rer Rem h gt h 0 h lt h d 3 7 h h d Rer Rem h d h h where L L T is the evapotranspiration rate per unit surface area of water table The evapotranspiration flow rate LT drawn from a model cell is Rer DELR DELC 3 8 3 6 1 MODFLOW Processing Modflow 83
202. e lag10 30 to 30 2 Standard Deviation log10 0 to 30 5 Correlation Length Field Yvidth in the l direction 0 to 1 1 Correlation Length Field Width in the J direction 0 to 1 Number of Cells in the l direction 2 to 500 30 Number of Cells in the J direction 2 to 500 30 Help Close GO Fig 5 6 The Field Generator dialog box The generated field is lognormally to base 10 distributed Using the Data Editor you can load the generated field into an area of the model grid where the columns and rows are regularly spaced see section 3 8 for how to load an ASCII matrix file The simulation of the hydraulic conductivity distribution produced in this way 1s unconditional because the hydraulic conductivity values are not constrained to match the measurement values In conditional simulation existing measurements are used which reduce the space of possible realizations The conditional generation of a single realization proceeds in five steps 1 The parameter value for each model cell is interpolated from the measurements using the Kriging method The correlation length is determined from the measurements 2 Anunconditional generation 1s performed using the Field Generator with the same correlation length correlation scale 3 The unconditionally generated values at the measurement locations are used to interpolate values for each model cell by using the Kriging method again 4 The di
203. e criterion is met If some of the coefficients in A are dependent on the concentration being solved as in the case of nonlinear sorption they must be updated in outer iterations 50 MXITER should be set to an integer greater than one only when a nonlinear sorption isotherm is included in the simulation For ITERI a value between 30 and 50 should be adequate for most problems Relaxation Factor is only used for the SSOR option a value of 1 0 is generally adequate Concentration Closure Criterion is the convergence criterion a value between 10 and 10 is generally adequate Before solving the system of transport equations it is normalized by dividing the concentration terms by the maximum concentration of all cells When the change of the normalized concentration at all cells during a inner iteration is less than or equal to this value iteration stops When it takes only one inner iteration to converge the solution 1s considered to have converged and the simulation proceeds to the next transport step Concentration Change Printout Interval The maximum concentration changes is printed out whenever the iteration number is an even multiple of this printout interval Set it to zero for printing only at the end of each stress period Include full dispersion tensor memory intensive This is a flag for treatment of dispersion tensor cross terms If this option is not used all dispersion cross terms will be 3 6 4 MT3DMS Processing Modflow 139
204. e distribution coefficient L 3 M SF is not used RC1 and RC2 are not used OK Cancel Help Fig 2 24 The Chemical Reaction Package MTRCT1 dialog box Fig 2 25 The Output Control MT3D MT3DMS dialog box gt To perform the transport simulation 1 Choose MT3D Run from the Models menu The Run MT3D MT3D96 dialog box appears Fig 2 26 2 Click OK to start the transport computation Prior to running MT3D PMWIN will use user specified data to generate input files for MT3D as listed in the table of the Run MT3D MT3D96 dialog box An input file will be generated only if the generate flag is set to EJ You can click on the button to toggle the generate flag between and Ll Generally you do not need to change the flags as PMWIN will care about the settings 2 2 Perform Transport Simulation with MT3D Processing Modflow a Run MT3D MT3D96 Ea MT3D Program filles pm5 mt3d mt3d exe gt Basic Transport Package c pmb5data samplel mtbtn1 dat Advection Package ic pmSdata samplet mtadv dat Dispersion Package c pmbdata samplel mtdsp1 dat Chemical Reaction Package c pmbdata samplel mtrctl dat Sink and Source Mixing Package lc omSdata samplel mtssm1 dat Options Regenerate all input files for MT3D Generate input files only don t start MT3D Cancel Help Fig 2 26 The Run MT3D MT3D96 dialog box gt Check simulation results and produce
205. e elevation of the bottom of the stream If the option Calculate stream stages in reaches is checked the depth d in each reach is calculated from Manning s equation under the assumption of a rectangular stream channel a 3 5 aa 3 24 where LT is the calculated stream discharge n is Manning s roughness coefficient w L is the width of the channel S 11 1 is the slope of the stream channel and C is a conversion factor see eq 3 22 Although n and C appear separately here only the values of n C or C n are used in the computer code You need therefore only to specify the value of n C in PMWIN Streamflow Routing Package x Parameters Stream Structure segment Number 1 Inflow to this Segment L 3 T 2018 5 Reach Number Stream Stage L 8 Streambed Hydraulic Conductance L 2 T 7 Elevation ofthe Streambed L 0 Elevation of the Streambed Bottom L 0 Width of the Stream Channel L 00 Slope ofthe Stream Channel 000 Manning s Roughness coeff n C 06 Parameter Number H jo il Position Column Raw 20 1 OK Cancel Help Fig 3 23 The Streamflow Routine Package dialog box 3 6 1 MODFLOW Processing Modflow 95 otreamflow Routing Package Parameters Stream Structure Simulate diversions from segments OK Cancel Help Fig 3 2
206. e groundwater head L When the head in the groundwater system is less than elevation of the base of the reservoir bed sediments leakage from the reservoir to the groundwater system is computed by Qres Cres Hres Hpressor 3 18 where Haesgo 15 the elevation of the base of the reservoir bed sediments gt specify the stages of reservoirs 1 Click the Stage button from the Reservoir Package dialog box Fig 3 21 A Stage Time Table of Reservoirs dialog box appears Fig 3 22 2 Select a reservoir number a row from the first table The reservoir number is corresponding to the number lacs see above The description column is a place for you to take notice 3 Type the observation time and the corresponding stage into the second table The observation time 15 measured from the start of the model simulation to which the measured stage pertains The Reservoir package requires the input of the starting and ending stages for each stress period These values are automatically determined by linear interpolation using the values specified in the Stage Time Table of Reservoirs dialog box If the starting time or the ending time is beyond the latest observation time the latest observed stage will be used 3 6 MODFLOW Processing Modflow 91 Reservoir stage 1s used to determine whether the reservoir boundary is activated for a model cell at the beginning of each time step The reservoir stage for each time step 1s once again
207. e hydraulic head h in a river cell is greater than the rate of leakage Qu from the river to the aquifer 1s calculated by eq 3 19 Cav Hay P gt 3 19 3 6 1 MODFLOW 92 Processing Modflow For the case that h is greater than Hay Qpyy is negative It means that water flows from the aquifer into the river and is removed from the groundwater model When h has fallen below the bottom of the riverbed the rate of leakage through the riverbed is given by eq 3 20 Cay Hay Reor h lt Rigo 3 20 The value Cg of a river cell is often given by K L W Criy a a M 3 21 where K is the hydraulic conductivity of the riverbed material L is the length of the river within cell W is the width of the river and M is the thickness of the riverbed If Chy is unknown it must be adjusted during a model calibration MODFLOW Streamflow Routing The Streamflow Routing package Prudic 1989 1s designed to account for the amount of flow in streams and to simulate the interaction between surface streams and groundwater Streams are divided into segments and reaches Each reach corresponds to individual cells in the finite difference grid A segment consists of a group of reaches connected in downstream order Streamflow is accounted for by specifying flow for the first reach in each segment and then computing streamflow to adjacent downstream reaches in each segment as inflow in the upstream reach plus o
208. e initial hydraulic head is 43 m everywhere The areal extent of the aquifer is assumed to be infinite large Except a confining bed clay in the second unit the sandy sediments of the aquifer are homogeneous horizontally isotropic with an average horizontal hydraulic conductivity of 0 0001 m s and vertical hydraulic conductivity of 0 00001 m s The specific yield of the first stratigraphic unit is 0 15 The specific storage of the aquifer is assumed to be 0 0001 1 m The properties of the confining bed are horizonal hydraulic conductivity 1 x 10 m s vertical hydraulic conductivity 1 x 10 m s elastic specific storage 0 002 1 m and inelastic specific storage 0 006 1 m To construct a new building an excavation pit with the size 200 m x 100 m is required The bottom elevation of the pit is 40 m The pit must be held dry for one year Your task is to calculate the required withdrawal rate and the distribution of subsidence after one year Modeling Approach and Simulation Results The aquifer is simulated using a grid of 3 layers 36 columns and 36 rows The extent of the model grid is fairly large Each model layer represents a stratigraphic unit The layer type 3 confined unconfined Transmissvity varies can be used for all layers as layers of this type switch between confined and unconfined automatically In the Layer Options dialog box the Interbed storage flag for the second layer is checked The pit is modelled a
209. e maintained throughout the optimization process For an adjustable parameter PARVALI is the parameter s starting value which together with the starting values of all other adjustable parameters it 1s successively improved during the optimization process To enhance optimization efficiency you should choose an initial parameter value which is close to what you think will be the parameter s optimized value You should note the following repercussions of choosing an initial parameter value of Zero 1 Limitation of the parameter adjustment is not possible see the discussion on RELPARMAX and FACPARMAX during the first optimization iteration if the starting value of a parameter is zero Furthermore FACORIG cannot be used to modify the action of RELPARMAX and for a particular parameter throughout the optimization process if that parameter s original value is zero 2 A relative increment for derivatives calculation cannot be evaluated during the first iteration for a parameter whose initial value is zero If the parameter belongs to a group for which derivatives are in fact calculated as Relative see INCTYP and DERINC below a non zero DERINCLB variable must be provided for that group 3 If a parameter has an initial value of zero the parameter can be neither tied nor a parent parameter as the tied parent parameter ratio cannot be calculated PARLBND and PARUBND are a parameter s lower and upper bounds respectively For a
210. e number of the coordinate pairs Refer to Appendix 2 for the format of the Line Map files gt import a DXF map or a Line map 1 Click the right mouse button on any of the DXF File or Line Map File edit fields and select a file from a Map Files dialog box 2 Ifnecessary use a scale factor to enlarge or reduce the appearance size of the map Then use the values in X and Y to shift the scaled map to the desired position For details see Scaling a vector graphic in sec 3 9 3 Click the colored button in the front of the edit field and select a color for the DXF map from a Color dialog box The color will be assigned to a DXF graphics entity if the entity s color is not defined in the DXF file A line map will always use the selected color 4 Check the check box next to the edit field The map will be displayed only when the box is checked DXF File Filename X Fig 4 12 The Maps Options dialog box 4 3 PMPATH Options Menu Processing Modflow 195 4 4 PMPATH Output Files Plots To create plot files choose Save Plot As from the File menu and specify the format and the file name in the Save Plot As dialog box Fig 4 13 Four formats are available Drawing Interchange Format DXF Hewlett Packard Graphics Language HP GL Windows Bitmap BMP and the PATHLINE file of MODPATH 1 x To select a format click the Format drop down box You can type in the file name in the file edit field directly o
211. e of Tied In the latter case the parameter plays only a limited role in the estimation process However the parameter to which the tied parameter 1s linked this parent parameter must be neither fixed nor tied itself takes an active part in the parameter estimation process the tied parameter simply piggy backs on the parent parameter the value of the tied parameter maintaining at all times the same ratio to the parent parameter as the ratio of their initial values If a parameter is neither fixed nor tied and is not log transformed the parameter transformation variable PARTRANS must be supplied as None PARCHGLIM is used to designate whether an adjustable parameter is relative limited or factor limited See the discussion on RELPARMA X and FACPARMA X p 147 For tied or fixed parameters PARCHGLIM has no significance PARGP is the number of the group to which a parameter belongs Parameter groups are discussed in Group Definitions below PARTIED is the number of the parent parameter to which a parameter is linked See also PARTRANS SCALE and OFFSET Just before a parameter value is written to an input file of MODEFLOW it is multiplied by the real variable SCALE after which the real variable OFFSET 1s added The use of these two variables allows you to redefine the domain of a parameter Because they operate on the parameter value at the last moment before it is sent they take no part in the estimation process in fact they can
212. e same time The dashed curves represent the actual paths of these two particles The solid lines are the pathlines displayed by PMPATH The pathlines intersect each other although the particles exit points are exactly equal to that of the actual paths This effect can be prevented by using a smaller particle tracking step length such that intermediate particle positions between starting point and exit point can be calculated See Particle Tracking Time Properties dialog box sec 4 3 for how to change the particle tracking step length Consideration of the spatial discretization and water table layers The method described above is based on the assumption that the model domain was discretized into an orthogonal finite difference mesh 1 e all model cells in the same layer have the same thickness In practice variable layer thickness is often preferred for approaching varying thicknesses of stratigraphic geohydrologic units In order to calculate approximate groundwater paths for this kind of discretization PMPATH as well as MODPATH uses a vertical local coordinate instead of the real world z coordinate The vertical local coordinate is defined for each cell as Zoe ze ge 4 7 where 2 and 2 are the elevations of the bottom and top of the cell respectively According to this equation the vertical local coordinate Z is equal to 0 at the bottom of the cell and Z is equal 4 1 The Semi analytical Particle Tracking Method 180 Proc
213. e table is updated to reflect the changes you specified You can click on individual cell of the label column to turn label on or off Label height specifies the appearance height of the label text It uses the same length unit as the model Label spacing specifies the distance between two contour labels It uses the same length unit as the model Label Format The Label Format dialog box Fig 4 10 allows you to specify the format for the labels The Fixed option displays numbers at least one digit to the left and N digits to the 4 3 PMPATH Options Menu 190 Processing Modflow right of the decimal separator where N is the value specified in Decimal digits The Exponential option displays numbers in scientific format and E is inserted between the number and its exponent Decimal digits determines the number of digits to the right of the decimal separator For example if Decimal digits 2 the value 1241 2 will be displayed as 1241 20 for the fixed option or 1 24E 03 for the exponential option Prefix isa text string that appears before each label Suffix is a text string that appears after each label Restore Defaults Clicking on this button PMPATH sets the number of contour lines to 11 and uses the maxmum and minimum values found in the current layer as the minimum and maximum contour levels The label height and spacing will also be set to their default values Load and Save The contents of the contour le
214. e vertical direction is desired gt NPL is the number of initial particles per cell to be placed at cells where the relative cell concentration gradient DCCELL is less than or equal to DCEPS Generally NPL can be set to zero since advection is considered insignificant under the condition DCCELL lt DCEPS Setting NPL equal to NPH causes a uniform number of particles to be placed in every cell over the entire grid 1 e the uniform approach gt is the number of initial particles per cell to be placed at cells where the relative cell concentration gradient DCCELL is greater than DCEPS The selection of NPH depends on the nature of the flow field and also the computer memory limitation Generally use a smaller number in relatively uniform flow fields and a larger number in relatively nonuniform flow fields However values exceeding 16 in two dimensional simulations or 32 in three dimensional simulations are rarely necessary If the random pattern is chosen NPH 3 6 3 MT3D Processing Modflow 123 particles are randomly distributed within the cell block If the fixed pattern 1s chosen NPH is divided by NPLANE to yield the number of particles to be placed per plane which is rounded to one of the values shown in Fig 3 42 gt NPMIN is the minimum number of particles allowed per cell If the number of particles in a cell at the end of a transport step is fewer than NPMIN new particles are inserted into that cell to maintain a suffi
215. each layer The total pumping rate for the multilayer well 1s equal to the sum of the pumping rates from the individual layers The pumping rate for each layer Q can be approximately calculated by dividing the total pumping rate Q _ _ in proportion to the layer transmissivities McDonald and Harbaugh 1988 total tk 2 1 Q E total where is the transmissivity of layer k and 2T is the sum of the transmissivities of all layers penetrated by the multilayer well Unfortunately as the first layer is unconfined we do not exactly know the saturated thickness and the transmissivity of this layer at the position of the well Eq 2 1 cannot be used unless we assume a saturated thickness for calculating the transmissivity An other possibility to simulate a multi layer well 1s to set a very large vertical hydraulic conductivity or vertical leakance e g 1 m s to all cells of the well The total pumping rate is assigned to the lowest cell of the well For the display purpose a very small pumping rate say 1x10 m s can be assigned to other cells of the well In this way the exact 2 Run a Steady State Flow Simulation Processing Modflow 17 extraction rate from each penetrated layer will be calculated by MODFLOW implicitly and the value can be obtained by using the Water Budget Calculator see below As we do not know the required pumping rate for capturing the contaminated area shown in Fig 2 1 we will try a total pum
216. ecified concentration for species 1 to 30 Concentration of species 1 to 30 in a Time variant specified concentration cell Initial concentraion for the sorbed phase of species 1 to 30 Concentraion of species 1 to 30 associated with the recharge Concentraion of species 1 to 30 associated with the evapotranspiration First sorption constant of species 1 to 30 Second sorption constant of species 1 to 30 Appendix 4 Internal Data Files of PMWIN Processing Modflow 561 701 731 761 901 931 961 990 730 760 790 930 960 990 1101 1130 1131 1160 1301 1330 ZONE ZONE ZONE ZONE ZONE ZONE ZONE ZONE ZONE ZONE 323 First order rate constant for the dissolved phase of species 1 to 30 First order rate constant for the sorbed phase of species 1 to 30 Specified concentration of species 1 to 30 at constant head cells Specified concentration of species 1 to 30 at general head boundary cells Specified concentration of species 1 to 30 associated with injection wells Specified concentration of species 1 to 30 associated with river cells Specified concentration of species 1 to 430 associated with stream cells Flag indicates a Time variant specified concentration for species 1 to 30 Concentration of species 1 to 430 in a Time variant specified concentration cell Initial concentration for the sorbed phase of species 1 to 30 Other Reserved File Extensions Extensio
217. ed on by selecting Models Modflow Wetting Capability The wetting iteration interval 1s 1 wetting factor is 0 5 and THRESH is 1 for all cells The specific yield and 6 2 8 Simulation of Lakes 268 Processing Modflow effective porosity of all cells within the mining site lake are set to 1 Compared to the specific yield the influence of the confined storage coefficient within the lake is very small and can normally be ignored Therefore the specific storage coefficient S 0 0001 is assigned to all cells A transient flow simulation is performed for a stress period with the length of 3 15576E 08 seconds 100 time steps and a time step multiplier of 1 0 The temporal development curve of the water table at the a borehole which 1s located in the fourth layer within the lake 1s shown in Fig 6 34 The final stage in the lake is about 97 1 m 21E 1 I 0 3 1 BE 8 Fig 6 34 Temporal development curve of the water stage in the artificial lake 6 2 8 Simulation of Lakes Processing Modflow 269 6 3 EPA Instructional Problems Folder 5 Instructional Problems Overview of the Problems The manual of instructional problems for MODFLOW Andersen 1993 is intended to allow the student
218. ee options for specifying the cell in each vertical column of cells that receives the recharge 3 6 1 MODFLOW 88 Processing Modflow Recharge is only applied to the top grid layer 2 Vertical distribution of recharge is specified in the Layer Indicator array which defines the layer where recharge is applied 3 Recharge is applied to the highest active cell in each vertical column The user does not have to predetermine the layer to which recharge should be applied The appropriate layer 1s automatically selected by the Recharge package If the highest active cell is a constant head cell recharge will be intercepted and cannot go deeper Refer to the description of the Recharge package in McDonald and Harbaugh 1988 for an example of using these options MODFLOW Reservoir The Reservoir package Fenske et al 1996 is designed for cases where reservoirs are much greater in area than the area represented by individual model cells More than one reservoir can be simulated using this package The area subject to inundation by each reservoir 1s specified by entering the reservoir number for selected cells For reservoirs that include two or more areas of lower elevation separated by areas of higher elevation the filling of part of the reservoir may occur before spilling over to an adjacent area The package can simulate this process by specifying two or more reservoirs in the area of a single reservoir Reservoirs are defined by
219. eet You can then view the results or save them in ASCII or SURFER compatible data files Simulation results include hydraulic heads drawdowns cell by cell flow terms compaction subsidence Darcy velocities concentrations and mass terms The Field Interpolator takes measurement data and interpolates the data to each model cell The model grid can be irregularly spaced The Water Budget Calculator not only calculates the budget of user specified zones but also the exchange of flows between such zones This facility is very useful in many practical cases It allows the user to determine the flow through a particular boundary The Field Generator generates fields with Introduction 2 Processing Modflow heterogeneously distributed transmissivity or hydraulic conductivity values It allows the user to statistically simulate effects and influences of unknown small scale heterogeneities The Field Generator is based on Mej a s 1974 algorithm The Graph Viewer displays temporal development curves of simulation results including hydraulic heads drawdowns subsidence compaction and concentrations Using the Presentation tool you can create labelled contour maps of input data and simulation results You can fill colors to modell cells containing different values and report quality graphics may be saved to a wide variety of file formats including SURFER DXF HPGL and BMP Windows Bitmap The Presention tool can even create and display two dimens
220. ek Axel Voss and Jinhui Zhang who tested the software and provided many valuable comments and criticisms For their encouragement and support we thank Ian Callow Lothar Moosmann Renate Taugs Gerrit van Tonder and Ray Volker The authors also wish to thank Alpha Robinson a scientist at the University of Paderborn who checked Chapter 3 of this user s guide And thanks to our readers and software users it 1s not possible for us to list by name here all the readers and users who have made useful suggestions we are very grateful for these Wen Hsing Chiang Wolfgang Kinzelbach Hamburg Z rich December 1998 Processing Modflow 1 1 Introduction The applications of MODFLOW a modular three dimensional finite difference groundwater model of the U S Geological Survey to the description and prediction of the behavior of groundwater systems have increased significantly over the last few years The original version of MODFLOW 88 McDonald and Harbaugh 1988 or MODFLOW 96 Harbaugh and McDonald 1996a 1996b can simulate the effects of wells rivers drains head dependent boundaries recharge and evapotranspiration Since the publication of MODFLOW various codes have been developed by numerous investigators These codes are called packages models or sometimes simply programs Packages are integrated with MODFLOW each package deals with a specific feature of the hydrologic system to be simulated such as wells recharge or river Mod
221. el Move the grid cursor to the upper right cell 30 1 1 7 Move the grid cursor from the upper right cell 30 1 1 to the lower right cell 30 30 1 The value of 1 1s duplicated to all cells on the east side of the model 8 Turn on layer copy by clicking the layer copy button Layer copy 15 on if the relief of the layer copy button is sunk The cell values of the current layer will be copied to other layers if you move to the other model layer while layer copy is on You can turn off layer copy by clicking the layer copy button again 9 Move to the second layer and then to the third layer by pressing the PgDn key twice The cell values of the first layer are copied to the second and third layers 10 Choose Leave Editor from the File menu or click the leave editor button ing Modflow SAMPLE1 PM5 Eile ale Options Help E Be eo __ no flow boundary 8 amp m contaminated areg zi 2 pumping well 9 constant hedd boundary h constant head boundary th no flow boundary n ime independent Boundary Condition IBOUND 7 Active positive Inactive 0 Fixed Head negative 1 Fig 2 6 Data Editor with a plan view of the model grid The next step 1s to specify the geometry of the model gt specify the elevation of the top of model layers 1 Choose of Layers TOP from the Grid menu PMWIN displays the model grid 2 Choose Reset Matrix from the Value
222. el grid 1 Select Grid gt Mesh Size 2 Refine the mesh around each of the three wells by halving the size of the following rows and columns Columns 8 9 10 11 12 13 and 14 Rows 7 8 9 10 11 and 12 The grid should now be refined around the wells and appear similar to Fig 6 8 3 Leave the Data Editor by File Leave Editor Yes LLL 0 0 a ee South Granite Hills Fig 6 8 Model discretization Step 4 Assign Model Data All the following data will be entered using the Data Editor The unconfined aquifer is the layer 1 in the model The silty layer and the confined aquifer is simply layer 2 and layer 3 it is possible to switch between layers in the Data Editor by using the Page Up and Page Down keys on the keyboard Aquifer types gt define the aquifer types 1 Open the Layer Options dialog box by Grid Layer Type 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River Processing Modflow 235 2 Make sure that for layer 1 the type is set to 1 unconfined and that Layers 2 and 3 are set to 3 confined unconfined 3 Click OK to exit the Layer Options dialog box Flow boundaries gt Tospecify the IBOUND data 1 Select Grid gt Boundary Condition g
223. ell and the third option simulates leakage to a specified layer for each active reservoir cell Inherent in the simulation of reserviors 1s that the reservoir only partially penetrates an active model cell If the reservoir fully penetrates a cell the reservoir leakage will be simulated in a lower cell Thus water exchange between the groundwater system and the reservoir takes place across the bottom of the reservoir and the top of the model cells 3 6 1 MODFLOW 90 Processing Modflow Leakage between the reservoir and the underlying groundwater system 1s simulated for each model cell corresponding to the inundated area by multiplying the head difference between the reservoir and the groundwater system by the hydraulic conductance of the reservoir bed Hydraulic conductance of the reservoir bed is given by eq 3 16 Caes HCpes DELC I DELR J Rb 3 16 where DELC I is the width of the model row 1 DELR J is the width of the model column J Reservoir bed thickness is substracted from the land surface elevation of the reservoir to obtain the elevation of the base of the reservoir bed sediments The elevation of the base of the reservoir bed sediments is used in computing leakage When the head in the groundwater system is above the base of the reservoir bed sediments leakage Qpes LT from or to the groundwater system is computed by eq 3 17 Qpes Cres Hres P 3 17 where Hpes is the reservoir stage L and h is th
224. ell by advection the concentration values at the cell interfaces between two neighboring cells are used For the upstream weighting scheme the interface concentration in a particular direction is equal to the concentration at the upstream node along the same direction For the central in space weighting scheme the interface concentration is obtained by linear interpolation of the concentrations at the two neighboring cells As denoted in Zheng and Wang 1998 the central in space scheme does not lead to intolerable numerical dispersion when the grid spacing is regular However if transport is dominated by advection the upstream weighting is preferred as the central in space weighting scheme can lead to excessive artificial oscillation gt Particle Tracking Algorithm is used in combination with the method of characteristics The particle tracking options are the same as provided in MT3D MT3DMS Dispersion MT3DMS and MT3D share the same dispersion parameters See MT3D Dispersion for details about the parameters In MT3DMS the concentration change due to dispersion alone can be solved with a fully explicit central finite difference scheme or an implicit upstream or central finite difference scheme with the Generlized Conjugate Gradient solver The implicit method does not have any stability constraint MT3DMS Chemical Reaction The required parameters are specified in the Chemical Reaction MT3DMS dialog box Fig 3 50
225. els or programs can be stand alone codes or can be integrated with MODFLOW A stand alone model or program communicates with MODFLOW through data files The advective transport model PMPATH Chiang and Kinzelbach 1994 1998 the solute transport model MT3D Zheng 1990 MT3DMS Zheng and Wang 1998 and the parameter estimation programs PEST Doherty et al 1994 and UCODE Poeter and Hill 1998 use this approach The solute transport model MOC3D Konikow et al 1996 and the inverse model MODFLOWP Hill 1992 are integrated with MODFLOW Both codes use MODFLOW as a function for calculating flow fields This text and the companion software Processing Modflow for Windows PMWIN offer a totally integrated simulation system for modeling groundwater flow and transport processes with MODFLOW 88 MODFLOW 96 PMPATH MT3D MT3DMS MOC3D PEST and UCODE PMWIN comes with a professional graphical user interface the supported models and programs and several other useful modeling tools The graphical user interface allows you to create and simulate models with ease and fun It can import DXF and raster graphics and handle models with up to 1 000 stress periods 80 layers and 250 000 cells in each model layer The modeling tools include a Presentation tool a Result Extractor a Field Interpolator a Field Generator a Water Budget Calculator and a Graph Viewer The Result Extractor allows the user to extract simulation results from any period to a spread sh
226. em needs to be simulated The problem is simulated using a grid of 40 rows 40 columns and 14 layers Fig 6 22 A uniform horizontal grid spacing of 125 feet 238 1 m is used and each layer is 5 feet 1 52 m thick The pond is in the upper left corner of the grid The boundaries along row and column are no flow as a result of the symmetry A fixed head boundary of 25 feet 7 62 m 15 specified along row 40 and column 40 for layers 10 14 a no flow boundary 15 assigned along row 40 and column 40 for layers 1 9 Without the recharge from the pond layers 1 9 are dry and the head in all the cells of layers 10 14 is 25 feet Recharge from the pond is applied to the horizontal area encompassed by rows 1 through 2 and columns 1 through 2 Recharge option Recharge is applied to the highest active cell 1s used so that recharge will penetrate through inactive cells down to the 6 2 4 Simulation of a Water Table Mound resulting from Local Recharge 254 Processing Modflow water table The specific recharge rate of 0 05 foot per day 40 0152 m d simulates leakage of 3 125 cubic feet per day 88 5m d through one quarter of the pond bottom a simulated area of 62 500 square feet 25806 m Model Grid Configuration Cross Section infiltration pond 7 pond leakage e ese TTE 60 N T E 50 Groundwater S 40 7 30L Water table _ HH Edd HHH H oH AHHH 20 ratio of horizontal
227. ence between adjacent vertical cells along the mound For example the cell at layer 4 row 3 column 4 1s supposed to be dry even though the head in the horizontally adjacent cell in column 3 is 1 4 feet above the bottom of the layer The vertical head difference between cells in this part of the model is much less the difference between the head at the cell in layer 4 row 3 column 3 and the cell below 15 only 0 05 foot Thus the neighboring cell to the right 1s repeatedly and incorrectly converted to wet during the solution process if horizontal wetting is used with a wetting threshold of 0 5 foot The larger wetting threshold and wetting iteration interval used in the second simulation allow convergence to occur but only after many iterations In this simulation head in adjacent vertical cells is the best indicator of when a dry cell should become wet The formation of the groundwater mound over time can be obtained with a transient simulation The transient simulation is run for one stress period with a length of 500 000 days The stress period is divided into 50 time steps with a time step multiplier of 1 3 The first time step 1s 0 3 days and the last time step is 115 385 days The specific yield 1s 20 percent and the confined storage coefficient is 0 001 The PCG2 solver is used and cells are activated by comparison of the wetting threshold to heads in underlying cells The head change criterion for closure is 0 001 foot and the residual change
228. ene 318 Appendix 5 Using PMWIN with your MODFLOW 324 Appendix 6 Running MODPATH with PMWIN 326 8 ReferenceS 2252555555552 5 2 RU EU M UE E E ED E EE 327 Preface Welcome to Processing Modflow A Simulation System for Modeling Groundwater Flow and Pollution Processing Modflow was originally developed for a remediation project of a disposal site in the coastal region of Northern Germany At the beginning of the work the code was designed as a pre and postprocessor for the groundwater flow model MODFLOW Several years ago we began to prepare a Windows version of Processing Modflow with the goal of bringing various codes together in a complete simulation system The size of the program code grew as we began to prepare the Windows based advective transport model PMPATH and add options and features for supporting the solute transport models MT3D MT3DMS and MOC3D and the inverse models PEST and UCODE As in the earlier versions of Processing Modflow our goal is to provide an integrated groundwater modeling system with the hope that the very user friendly implementation will lower the threshold which inhibits the widespread use of computer based groundwater models To facilitate the use of Processing Modflow more than 60 documented ready to run models are included in this software Some of these models deal with theoretical background some of them are of practical values The present text ca
229. ent is expected to be large in this case it is around the wells In PMWIN grid refinement takes place within the Grid 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge 218 Processing Modflow gt Mesh Size and it is quite easy to add additional rows and columns to an existing mesh This is done by using a combination of holding down the CTRL key and using the arrow keys as follows CTRL Up arrow add a row CTRL Down arrow remove an added row CTRL Right arrow add a column CTRL Left arrow remove an added column It is also possible to specify the row and column spacing of individual cells by clicking the right mouse button within the cell of interest however we will not be doing that in this exercise gt refine the mesh around the pumping wells 1 If you aren t already in the Grid Editor enter by Grid Mesh Size 2 Zoom in around Well 1 by clicking on the amp button and then dragging a box around the general area of Well 1 3 Change back to the button and click on the cell containing Well 1 Divide this column into three by adding two additional columns CTRL Right arrow followed by CTRL Right arrow 5 Divide the row also into three by CTRL Up arrow followed by CTRL Up arrow You should see dashed lines where the new rows and columns will be placed 6 Zoom out by pressing the SJ button You will notice that the rows and columns added extend throughout the mo
230. enu Processing Modflow 79 Inaconfined layer the storage term 15 given by storativity or confined storage coefficient specific storage 11 x layer thickness L The storativity is a function of the compressibility of the water and the elastic property of the soil matrix The specific storage or specific storativity 1s defined as the volume of water that a unit column of aquifer releases from storage under a unit decline in hydraulic head The specific storage ranges in value from 3 3 10 m of rock to 2 0 x 10 m of plastic clay Domenico 1972 The confined storage coefficient is required by layers of type 0 2 and 3 PMWIN uses specific storage and the layer thickness to calculate the confined storage coefficient 1f the corresponding Storage Coefficient flag in the Layer Options dialog is Calculated By setting the Storage Coefficient flagto User Specified and choosing Storage Coefficient from the Parameters menu you can specify the confined storage coefficient directly Inaphreatic an unconfined layer the storage term is given by specific yield or drainable porosity Specific yield is defined as the volume of water that an unconfined aquifer releases from storage per unit surface area of aquifer per unit decline in the water table Specific yield 1s a function of porosity and is not necessarily equal to porosity becuase a certain amount of water is held in the soild matrix and cannot be removed by gravity drainage Specific yie
231. ep at cell 1 k can be expressed as At Pp Ay Cii M 3 47 Fi ik ll ik ijk where A is the first order rate constant for the dissolved phase is the first order rate constant for the sorbed phase At is the transport time step and C 18 the mass of the solute species adsorbed on the solids per unit bulk dry mass of the porous medium at the 3 6 3 MT3D 128 Processing Modflow beginning of each transport step C 15 in equilibrium with solute concentration in the cell j 1 The rate constant is usually given in terms of the half life t see eq 3 32 Generally if the reaction is radioactive decay A should be set equal to However for certain types of biodegradation A may be different from A MT3D Chemical Reaction Cell by Cell only MT3D96 Chemical Reactions Package 2 supported by the MT3D96 transport model includes all functions of the Chemical Reactions Package of MT3D version 1 xx Using the Data Editor chemical reaction coefficients may be entered on a three dimensional cell by cell basis This option provides the ability to have different reaction coefficients for different areas in a single model layer See MT3D Chemical Reaction Layer by Layer for details about the parameters MT3D gt Sink Source Concentration This menu is used for specifying the concentration associated with the fluid of point or areally distributed s
232. equilibrium sorbed or immobile liquid phase Bulk density of the porous medium M L 3 2700 Distribution Coefficient Kd L 3 M 0 0031 25 Mass transfer rate between dissolved and sorbed phases 1 T D First order reaction rate for the dissolved phase 1 T D First order reaction rate for the sorbed phase 1 T Initial concentration for the sorbed phase M M 0 Porosity of the immobile domain Cancel Help Fig 3 50 The Chemical Reaction MT3DMS dialog box First order kinetic sorption When the local equilibrium assumption is not valid it 15 assumed in MT3DMS that sorption can be represented by a first order reversible kinetic sorption described by ac C e 4 P p K e where B T is the first order mass transfer rate between the dissolved and sorbed phases ML is the bulk density of the porous medium C is the sorbed concentration and Ky L M is the distribution coefficient as defined previously in eq 3 41 Eq 3 48 can be rearranged in C K B 3t 3 49 If sufficient time is available for the system to reach equilibrium for example the flow velocity of groundwater is very slow then there is no further change in C and dC ot 0 so that eq 3 49 1s reduced to linear sorption eq 3 41 If the first order mass transfer rate 3 6 4 MT3DMS 136 Processing Modflow is infinitely large the right hand side of eq 3 49 1s equal to zero which also leads
233. er flows through a valley Fig 6 7 which is bounded to the north and south by impermeable granitic intrusions The hydraulic heads at the upstream and downstream fixed head boundaries are known which are saved in a data file The river forms part of a permeable unconfined aquifer system horizontal hydraulic conductivity K 5 m day vertical hydraulic conductivity K 0 5 m day specific yield Sy 0 05 effective porosity n 0 2 which overlies a confined aquifer of a variable thickness K 2 m day K 1 m day specific storage Ss 5 10 0 25 A 2 m thick silty layer K 0 5 m day K 0 05 m day n 0 25 separates the two aquifers The elevations of the aquifer tops and bottoms are known and saved in data files Three pumping wells pumping at 500 m day each abstract water from the confined aquifer Your task is to construct a 3 layer groundwater flow model of the area including the river and the pumping wells and to assess the capture zone of the wells Big River upstream fixed head boundary 5000 m downstream fixed head boundary South Granite Hills 6750 m SS Fig 6 7 Model area 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River Processing Modflow 233 Step 1 Create a New Model gt create a new model 1 Select File gt New Model 2 Inthe New Model dialog box change the working folder to pm5 examples T2 create the folder if it does not exist and enter T2
234. er table aquifer results in formation of a ground water mound For example a ground water mound may form in response to recharge from infiltration ponds commonly used to artificially replenish aquifers or to remove contamination by filtration through a soil column If the aquifer has low vertical hydraulic conductivity or contains interspersed zones of low hydraulic conductivity it may be necessary to simulate the aquifer using multiple model layers in which the mound crosses more than one layer The conceptual model consists of a rectangular unconfined aquifer overlain by a thick unsaturated zone Fig 6 22 The horizontal hydraulic conductivity 1s 5 feet per day and vertical hydraulic conductivity is 0 25 feet per day 0 0762 m d A leaking pond recharges the aquifer resulting in the formation of a ground water mound The pond covers approximately 6 acres 23225 m and pond leakage is 12 500 cubic feet per day 354 m d The specific yield is 20 percent The water table is flat prior to the creation of the recharge pond The flat water table is the result of a uniform fixed head boundary that surrounds the aquifer Your task is to calculate the water table under the steady state condition and the formation of the groundwater mound over time Modeling Approach and Simulation Results Because of the symmetry heads are identical in each quadrant of the aquifer and there is no flow between quadrants therefore only one quarter of the syst
235. eral benchmark problems and application examples are introduced in the user s guides of MT3D Zheng 1990 MT3DMS Zheng and Wang 1998 and MOC3D Konikow et al 1998 You can find these documentations on the folders document mt3d document mt8dms and document moc3d of the companion CD ROM Either analytical solutions or numerical solutions by another code can serve as benchmark problems Modeling Approach and Simulation Results Using PMWIN we have rebuilt most of the benchmark problems of MT3D MT3DMS and MOC3D If you have selected to install the component Solute transport during the installation of PMWIN you can find the models in the sub folders under PM5Yexamples Transport listed in Table 6 7 All these models are ready to run It is recommended that the users try these test problems first to become familiarized with the various options before applying MT3D MT3DMS or MOC3D to solve their own problems Table 6 7 Benchmark problems and application examples of MT3D MT3DMS and MOC3D Folder Description PM5 TRANSPORT3 This model is described in section 7 5 of the manual of 5 A numerical model consisting of 31 columns 31 rows and 1 layer is used to simulate the two dimensional transport in a radial flow field numerical results were compared with the analytical solution of Moench and Ogata 1981 PM5 TRANSPORT4 This model is described in section 7 6 of the manual of 5 A numerical model consisting of 31
236. erlaid by geologic formations which are not completely impermeable and can transmit water at a sufficient rate Fig 6 41 Hantush and Jacob 1955 give an analytical solution to describe the drawdown with time during pumping with a well in a leaky confined aquifer In addition to the assumptions in the Theis solution the analytical solution requires two assumptions the hydraulic head in the overlying oder underlying aquifer 1s constant during pumping in the leaky confined aquifer and the rate of leakage into the pumped aquifer is proportional to drawdown In this example a pumping well withdraws water at a constant rate from the leaky confined aquifer The drawdown of the hydraulic head is monitored with time at a borehole 55m from the pumping well The borehole 1s located in the leaky confined aquifer The initial hydraulic head is 8 m everywhere Specific yield and effective porosity 0 1 The other aquifer parameters are given in Fig 6 41 The analytical solution for this case is given in Table 6 6 Your task 1s to construct a numerical model calculate the drawdown curve at the borehole and compare it with the Hantush Jacob solution Note that the parameters for the confined leaky aquifer are the same as in the previous example so we can compare the results of these two examples Table 6 6 Analytical solution for the drawdown with time Time s drawdown m Time s drawdown m 123 0 0067 4932 0 336 247 0 03 12330 0 449 352 0
237. ert or delete a column and or a row Inserting or deleting columns rows is only possible when using the Grid Editor for the first time 1 Click the assign value button l 2 Move the grid cursor to the desired cell by using the arrow keys or by clicking the mouse on the desired position 3 Hold down the Ctrl key and press the up or right arrow key to insert a row or a column press the down or left arrow key to delete the current row or column gt refine a column and or a row Refining columns rows is only possible when the grid has already been saved 3 The Grid Editor Processing Modflow 57 Click the assign value button l 2 Move the grid cursor to the desired cell by using the arrow keys or by clicking the mouse on the desired position 3 Hold down the Ctrl key and press the up or right arrow key to refine a row or a column press the down or left arrow key to remove the refinement The refinements of a column or a row are shown on the status bar imi Model Dimension OK Number f3 EN Cancel Columns Help Number 20 Size 20 Rows Number 20 Size 20 Fig 3 2 The Model Dimension dialog box iz Processing Modflow SAMPLE1 PM5 BEES File Value Options Help aja sla sur Worksheet Grid cursor ni flow bpiindary gl m TA 20 ir T8105 boundary VA AAA
238. es The real world coordinates eastings x northings and the layer number of each borehole are given in the table A borehole is active if the Active flag is checked While you are editing your model data using the Data Editor active boreholes and the corresponding borehole name can be displayed After a simulation PMWIN will interpolate the simulation results to the active boreholes So you may use the Graph Viewer Tools Graph to display the temporal development of a certain result type for example head time curves or breakthrough curves You can also use the Graph Viewer to display a scatter diagram for comparing the Observed and calculated values 3 5 The Parameters Menu Processing Modflow 77 gt Observations The name of the borehole at which the observations are made is given in Borehole name The observation time to which the measurement pertains is measured from the beginning of the model simulation You must specify the observation times in ascending order If you use inverse models PEST or UCODE for calibrating a steady state flow model with one stress period you may run a steady state flow simulation over several stress periods the length of the period is given as the observation time The Weight of an observation gives a relative confidence level of the observed value The higher the value the better is the measurement The weight can be set at zero if you wish meaning that the observation takes no part in the
239. es an input file only if the corresponding Generate flag is checked You may click on a flag to check or uncheck it Normally you do not need to worry about these flags as PMWIN will take care of the settings gt Options Regenerate all input files for MT3D You should check this option if the input files have been deleted or overwritten by other programs Regenerate input files only don t start MT3D Check this option if you do not want to run MT3D You can start the simulation at a later time by executing the batch file MT3D BAT gt Click OK to start the generation of MT3D input files In addition PMWIN generates a batch file MT3D BAT saved in your model directory When all necessary files are generated PMWIN automatically runs MT3D BAT in a DOS window During a flow simulation MT3D saves results to various output files and writes a detailed run record to the listing file OUTPUT MT3 saved in your model folder See MT3D Output Control for details about the output terms Run MT3D MT3D96 x MT3D Program c program files pm5 mt3d mt3d exe gt Basic Transport Package c program files pm5 examples sample Advection Package c program files pm5 examples samplet Dispersion Package c program files pm5 examples samplel Chemical Reaction Package 2 c program filesxipm5NexamplesNsamplel Sink and Source Mixing Package c program files pm5 examples sampletl Options Regener
240. ese particles Particles are tracked forward through the flow field using a small time increment At the end of each time increment the average concentration at a cell due to advection alone is evaluated from the concentrations of particles which happen to be located within the cell The other terms in the governing equation 1 e dispersion chemical reaction and decay are accounted for by adjusting the concentrations associated with each particle A moving particle in a ground water flow system will change velocity as it moves due to both spatial variation in velocity and temporal variations during transient flow During a flow time step advection is determined from velocities computed at the end of the flow time step Temporal changes in velocity are accounted for by a step change in velocity at the start of each new flow time step After the flow equation is solved for a new time step the specific discharge across every face of each finite difference cell 1s recomputed on the basis of the new head distribution and the movement of particles during this flow time step is based only on these specific discharges MOC3D provides two interpolation options linear and bilinear interpolation for calculating the spatial variation of the particle velocity from the specific discharges Konikow et al 1996 indicate that if transmissivity within a layer is homogeneous or smoothly varying bilinear interpolation of velocity yields more realistic pathlines fo
241. essing Modflow to 1 at the top of the cell When a particle is moved laterally from one cell to another its vertical local coordinate remains unchanged regardless of how the elevations of the bottom and top vary from one cell to another In MODFLOW model layers of type 1 unconfined are always water table layers model layers of type 2 or 3 confined unconfined are water table layers when the head in the cell is beneath the elevation of the cell top For water table layers Z is set equal to the head in the cell 0 Wi M 0 w Fig 4 4 Schematic illustration of the spurious intersection of two pathlines in a two dimensional cell 4 2 PMPATH Modeling Environment The PMPATH modeling environment Fig 4 5 consists of the Worksheet the cross section windows the tool bar and and the status bar They are described below Worksheet and cross section windows PMPATH as well as PMWIN use the same spatial discretization convention as used by MODFLOW An aquifer system is discretized into mesh blocks or cells An I J K indexing system is used to describe the locations of cells in terms of rows columns and layers The I J and K axes are oriented along the row column and layer direction respectively The origin of 4 2 PMPATH Modeling Environment Processing Modflow 181 the cell indexing system 15 located at the upper top left cell of the model MODFLOW numbers the layers from the top down an increment
242. ew Model 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge Processing Modflow 217 Step1 Create a New Model gt Tocreate a new model 1 Select File gt New Model 2 Inthe New Model dialog box change the working folder to pm5 examples T1 create the folder if 1 does not exist and enter as the name of the new model to be created 3 Click OK to exit this dialog box Step 2 Define Model Size gt To define the size of the model 1 Select Grid Mesh Size 2 Inthe Model Dimension dialog box enter Layers Number 1 Columns Number 12 Size 500 Rows Number 20 Size 500 3 Click OK to exit this dialog box You are now in the Grid Editor of PMWIN To help visualize the problem we can overlay a DXF file as a map which gives us the locations of the boundaries and the pumping wells gt To load a map 1 Select Options Maps to open the Map Options dialog box 2 Click the box beside the space for the DXF filename to activate that particular map it 1s also possible to choose a color by clicking on the colored square 3 In the first filename field of DXF files click the right mouse button to bring up the Map Files dialog box 4 Choose BASEMAPI DXF from the folder pm5 examples tutorials tutorial1 click OK to exit the dialog box 5 Click OK to exit the Map Options dialog box Step 3 Refine Model Grid It is good practice to use a smaller grid in areas where the hydraulic gradi
243. extent of the worksheet is set to twice that of the model grid The first time you use the Grid Editor you can insert or delete columns or rows see below After leaving the Grid Editor and saving the grid you can subsequently refine the existing model grid by calling the Grid Editor again In each case you can change the size of any column or row If the grid 1s refined all model parameters are retained For example if the cell of a pumping well is divided into four cells all four cells will be treated as wells and the sum of their pumping rates will be kept the same as that of the previous single well The same 15 true for hydraulic conductance of the head dependent boundaries 1 e river stream drain and general head boundary If the Stream Routing Package is used you must redefine the segment and reach number of the stream gt change the width of a column and or a row 1 Click the assign value button The grid cursor appears only if the Assign Value button is pressed down You do not need to click this button if its relief is already sunk ie if it is already active 2 Move the grid cursor to the desired cell by using the arrow keys or by clicking the mouse on the desired position The sizes of the current column and row are shown on the status bar 3 Press the right mouse button once The Grid Editor shows a Size of Column and Row dialog box Fig 3 4 4 Inthe dialog box type new values then click OK gt ins
244. f the stress period The interpolated heads are constant during a time step If a cell is specified as a time variant specified head boundary for a stress period and omitted in the specification for a subsequent period it remains a fixed head boundary with a head equal to that at the end of the previous period Hime Variant Specified Head Package StHead l hs End Head L 4 7 Current Position Column Row 21 20 If Flag lt gt 0 the current cell is a Time Variant Specified Head cell Cancel Help Fig 3 26 The Time Variant Specified Head Package dialog box 3 6 1 MODFLOW Processing Modflow 977 MODFLOW Well An injection or a pumping well is defined by using the Data Editor to assign two values to a model cell Rechage rate of the well Q L T and Parameter Number Negative cell values for the Rechage rate of the well are used to indicate pumping wells while positive cell values indicate injection wells The parameter number is used to assign Q as a parameter for an automatic calibration by the inverse models PEST see PEST gt Parameter List or UCODE Parameter List The injection or pumping rate of a well is constant during a given stress period and is independent of both the cell area and the head in the cell It is implicitly assumed by MODFLOW that a well penetrates the full thickness of the cell MODFLOW can simulate wells that penetrate m
245. fer to Appendix 5 for how to configure PMWIN to run with your own MODFLOW Inverse Code is the name of the nonlinear regression executable mrdrive exe as distributed If another inversion algorithm is used its full path and file name need to be specified here gt File Table PMWIN uses the user specified data to generate input files of MODFLOW and UCODE Description gives the name of the packages used in the flow model The path and name of the input file are shown in Destination File PMWIN generates an input file only if the corresponding Generate flag is checked You may click on a flag to check or uncheck it Normally you do not need to worry about these flags as PMWIN will take care of the settings gt Options Regenerate all input files for MODFLOW and UCODE You should check this option if the input files have been deleted or overwritten by other programs Generate input files only don t start Check this option if you do not want to run UCODE You can start the simulation at a later time by executing the batch file UCODE BAT Check the model data Before creating data files for MODFLOW and UCODE PMWIN will check the geometry of the model and the consistency of the model data given in table 3 5 if this option is checked The errors if any are saved in the file CHECK LST located in the same folder as your model data gt Click OK to start the generation of the MODFLOW and input files
246. ffects are incorporated directly into appropriate changes in particle positions and concentrations A strong source or sink cell is indicated by the cell value of 1 MOC3D Observation Wells Cells of the transport subgrid can be designated as observation wells by assigning the value of 1 to the cells At each observation well the time head and concentration after each particle move will be written to the separate output file MOCOBS OUT saved in the same folder as your model data Note that this feature 1s to facilitate graphical postprocessing of the calculated data using other software packages outside of PMWIN MOC3D Sink Source Concentration This menu is used for specifying the concentrations of point or areally distributed sources including fixed head cells general head boundary cells rivers wells and recharge cells Except the concentrations associated with fixed head cells all source concentrations are specified by using the Data Editor If the concentration of a fluid source is not specified the default value for the concentration is zero The source concentration associated with the fixed head cells are specified in the Source Concentration Fixed Head dialog box Fig 3 37 The fixed head cells are grouped into zones which are defined by specifying unique negative values to the IBOUND array see section 3 4 Each zone has an associated source concentration The concentration in the fluid leaving the aquifer at fluid sinks i
247. fined and unconfined Confined storage coefficient specific storage x layer thickness is used to calculated the rate of change in storage if the layer is fully saturated otherwise specific yield will be used Transmissivity of each cell 15 constant throughout the simulation Vertical leakage from above is limited if the layer desaturates Type3 A layer of this type is fully convertible between confined and unconfined Confined storage coefficient specific storage x layer thickness 1s used to calculate the rate of change in storage if the layer is fully saturated otherwise specific yield will be used During a flow simulation transmissivity of each cell varies with the saturated thickness of the aquifer Vertical leakage from above is limited if the layer desaturates gt Anisotropy factor The anisotropy factor is the ratio of transmissivity or hydraulic conductivity whichever is being used along the I direction to transmissivity or hydraulic conductivity along the J direction The principal axes of the conductivity tensor must be parallel to the I and J axes of your model grid 3 4 The Grid Menu 70 Processing Modflow if the anisotropy factor is not equal to 1 Note that anisotropy as used here does not refer to the ratio of horizontal to vertical hydraulic conductivity see Leakance below Layer Options x Anisotropy T 111 Unconfined Calculated Calculated e 3 Confined Unconfined Calculated Calculated
248. for the real world display mode only the BMP format can be used WF Model Information Ea Simulation title Tutorial 1 for Processing Modflow for Windows Cancel About this model Model c pmbdata samplel samplel pm5 Number of Rows 30 Number of Columns 30 Number of Layers 3 Number of Stress Periods 1 Simulation Flow Type Steady State Simulation Time Unit seconds Fig 3 12 The Model Information dialog box Save Plot As x Format File c pmSdata samplet sample dxt 2d Cancel Help Fig 3 13 The Save Plot As dialog box Print Plot This menu item is only activated in the Data Editor After selecting this item a Print Plot dialog box 1s displayed with a preview window The options are described below Use full page The plot is scaled to fit the paper the original aspect ratio will not be changed Center on page The plot is place on the center of the page Image Size millimeters Specify the width and height of the printed image in millimeters Margins millimeters Specify the left and top margins of the image in millimeters A Printer A Printer dialog box allows you to select an installed printer and specify the print quality the paper size source and orientation and other printing parameters A Print Print the contents shown on the preview window 3 3 The File Menu 68 Processing Modflow A Close Close the Print Plot dialog box without printing
249. ftware packages and imported as long as the format is the same as that required by PMWIN 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge 226 Processing Modflow The general procedure for loading data files into the model will be demonstrated using the head values since we need to visualise these and also use them as the starting heads in the following transient simulation Step 7 Produce output from the steady state flow simulation Visualization and output 1s best performed in the Presentation part of the program as this will not affect any part of the MODFLOW data To load the data into the Presentation matrix v From the main menu select Tools Presentation Open the Browse Matrix dialog box by Value Matrix In the Browse Matrix dialog box select Load to open the Load Matrix dialog box Click on L Jand select the appropriate file to load In this case itis TISS DAT Now click on OK 5 Exit the Load Matrix dialog box by clicking on OK The data will appear in the Browse Matrix dialog box click on OK to exit this dialog box p e A and return to the Data Editor The data 1s now loaded gt view contours of the data Select Options Environment to open the Environment Options dialog box 2 Click the Contours tab and make sure the Visible box is checked Click on the header Level of the table to change the contour minumum to 12 5 maximum to 19 and the contour interval to 0 5 It is also possible
250. g 4 11 The Particle Tracking Time Properties dialog box Simulation Mode Time Current Time In MODFLOW simulation time is divided into stress periods which are in turn divided into time steps The time length of each stress period and time step is defined in PMWIN In PMPATH you can move to any stress period and time step as long as the resulting heads and budget data are saved for that stress period time step The starting time of each particle is always the beginning of the time step defined in Current Time Tracking Step To select a time unit for Step length click the down arrow on the Unit drop down box The step length is the time length that particles may move when one of the buttons or is pressed Maximum steps is the allowed number of particle tracking steps Each time you press one of the buttons or gt particles may move backward or forward for a time length defined by the product of Step length and Maximum steps Time Mark PMPATH places a time mark on pathlines for each n tracking step where n is given in Interval Check the corresponding Visible check boxes if you want to see time marks on the Worksheet plan view or the cross section windows The appearance 4 3 PMPATH Options Menu 192 Processing Modflow size of the time marks is defined by Size in pixels The default value of Size is 10 for the top view window and 3 for the cross section windows The sizes can be ranged from to 2 147 483 647 Simulation
251. g Modflow 205 6 6 Solute Transport 6 6 1 One Dimensional Dispersive Transport Folder pm5 examples transport transport Overview of the Problem This example demonstrates the use of the numerical transport model and compares the numerical results with the analytical solution A uniform flow with a hydraulic gradient of 2 exists in a sand column The hydraulic conductivity of the sand column is 100 m d The effective porosity is 0 2 The longitudinal dispersivity is 1 m A pollutant mass of 1 g is injected into the sand column instantaneously Your task 1s to construct a one dimensional numerical model and calculate the breakthrough curve concentration time curve at 20 m downstream of the injection point Calculate the breakthrough curve by using a longitudinal dispersivity of 4 m and compare these two curves Will the peak arrival time of the concentration be changed if only the longitudinal dispersivity is changed Modeling Approach and Simulation Results The numerical model of this example consists of one layer one row and 51 columns The thickness of the layer and the width of the row and column is m To obtain a hydraulic gradient of 2 the first cell and the last cell of the model are specifed as fixed head cells with initial hydraulic heads of 1 1 m and 1 0 m respectively The initial head of all other cells is 1 0 m A steady state flow simulation is performed for a stress period length of 100 days The injected mass of 1
252. g higher values for the exponent e g F 4 the interpolated cell values will approach the value of the nearest data point The surface is therefore relatively flat near all data points Lower values of the exponent e g F 1 produce a surface with peaks to attain the proper values at the data points A value of F 2 is suggested by Shepard 1968 5 2 The Field Interpolator Processing Modflow 203 Akima s bivariate interpolation This method creates a triangulation of the measurement data points and performs interpolation by using a bivariate fifth order polynomial of Hermite type for the interpolation within a triangle It uses a user specified number of data points closest to a model cell for estimating the value at the cell Renka s triangulation This method creates a triangulation of the measurement data points and uses a global derivative estimation procedure to compute estimated partial derivatives at each point The program determines a piecewise cubic function F x y F has continuous first derivates over the created mesh and extends beyond the mesh boundary allowing extrapolation Interpolated data value 10 20 3l 40 50 e esae data point Fig 5 2 Effects of different weighting exponents Kriging The Kriging method has been popularized by Math ron 1963 and is named in honor of D G Krige a noted South African mining geologist and statistician PMWIN assumes that the measurement data are stati
253. g test Drawdown Time T 4 93 4 Fig 6 42 Drawdown time curves 6 4 4 Transient Flow to a Well in a Leaky Confined Aquifer 282 Processing Modflow 6 5 Geotechnical Problems 6 5 1 Inflow of Water into an Excavation Pit Folder pm5 examples geotechniques geo Overview of the Problem This example is adopted from Kinzelbach and Rausch 1995 Fig 6 43 shows a plan view and a cross section through a shallow aquifer situated in a valley In the north the aquifer is bounded by the outcrop of the sediments in the valley while the south boundary is a river which 15 in contact with the aquifer The aquifer extends several kilometers to the west and east it is unconfined homogeneous and isotropic The top and bottom elevations of the aquifer are 7 m and m respectively The average horizontal hydraulic conductivity of the sandy sediments is 0 001 m s the effective porosity is 0 15 The groundwater recharge from precipitation is 6x10 m s m The water stage in the river is 5 m above the flat aquifer bottom which is the reference level for the simulation At a distance of 200 m from the river there is an excavation pit The length of the pit 15 200 m the width 100 m The bottom of the excavation is 3 m above the aquifer bottom Your task is to calculate the inflow into the pit and show head contours and catchment area of the pit Plane view no flow boundary ny 900 m excavation pit 200 x 100 m h 3m River
254. ge Factor IB4 CBC Starting Compaction 294 CBC Parameter numbers associated with IBS cells I1Z ZONE Zone file Recharge Package Extension Type Description RCH CBC Recharge flux L T RCI CBC Layer indicator array that defines the layer in each vertical column where recharge is applied 295 CBC Parameter numbers associated with recharge RHZ ZONE Zone file Reservoir Package Extension Type Description C85 CBC Location of reservoirs C86 CBC Bottom elevation of reservoir C87 CBC Bed conductivity of reservoir C88 CBC Bed thickness of reservoir C89 CBC Layer indicator of reservoir 296 CBC Parameter numbers associated with reservoir cells 285 Zone Zone file River Package Extension Type Description HIC CBC Hydraulic conductance of riverbed RIR CBC Elevation of the bottom of riverbed RIS CBC Water surface elevation of river 297 CBC Parameter numbers associated with River cells RCZ ZONE Zone file Streamflow Routine Package Extension Type Description SBO CBC Elevation of the bottom of the streambed SEG CBC Segment number sequential number assigned to a group of reaches SFL CBC otreamflow in length cubed per time SRE CBC Sequential number of reaches SRO CBC Manning s roughness coefficient C for each stream reach Appendix 4 Internal Data Files of PMWIN Processing Modflow 32 SSL CBC Slope of the stream channel in each reach SST CBC Stream stage STC CBC Streambed hydraulic conductance
255. ge using equation 71 in Cooper and Rorabaugh 1963 p 355 assuming a maximum flood stage of 4 ft above the initial river stage The streamflow distribution Fig 6 29 was calculated from the river stage distribution The river has a width of 100 ft a dimensionless roughness coefficient of 0 02377 and a slope of 0 0001 A constant C 1 486 should be used for the simulation see eq 3 22 Modeling Approach and Simulation Results Streamflow for the first 30 days was divided into I day periods for simulation Fig 6 30 shows the computed river stage The simulation results are the same as the manually calculated river stage values using equation 71 of Cooper and Rorabaugh 1963 p 355 Detailed discussion on the analytical and numerical results can be found in Prudic 1988 Results of varying both the number of columns and the length of stress periods used to simulate the flood wave indicate that both the number of columns and the length of the time step are important in exactly duplicating the analytical solution A groundwater flow model with the Streamflow Routing package has an advantage over 6 2 7 Simulation of a Flood in a River 264 Processing Modflow analytical solutions because it can be used to simulate complex systems An example Folder pm5 examples basic basic a containing a stream system Fig 6 31 is used to illustrate most of the features of the Streamflow Routing package The example assumes that an aquifer of 6 000 ft
256. h 1995 An impervious weir is partially embedded in a confined aquifer The aquifer is assumed to be homogeneous with a hydraulic conductivity of the aquifer of 0 0005 m s and a thickness of 9 m The effective porosity of the aquifer is 0 15 The boundary conditions are shown in Fig 6 45 Calculate the flow net and the flux through the aquifer for the cases that 1 the aquifer is isotropic and 2 the aquifer 1s anisotropic with an anisotropy factor of 0 2 water table h 12 m ui ud no flow boundary Fig 6 45 Problem description Modeling Approach and Simulation Results To compute the head distribution and the corresponding flowlines it 1s sufficient to consider a vertical cross section of the aquifer with a uniform thickness of 1 m The aquifer 1s simulated using a grid of one layer 65 columns and 9 rows A regular grid spacing of 1 m 1s used for each column and row The layer type is 0 confined Fig 6 46 shows the cross section the selected model grid and the boundary conditions The boundaries at the upstream and downstream of the weir are modeled as fixed head boundaries with h 12 m and h 10 m above reference level respectively The aquifer bottom and the weir itself are modelled as no flow boundaries Fig 6 47 shows the flow net for the isotropic case The head values range from 10 to 12 m with a head increment of 0 1 m The flux through the aquifer per m width of the weir is 3 65x10 m s m 31 56 m day m
257. hat the mass balance calculation is itself just an approximation Using Presentation you can generate contour maps of the calculated concentration Fig 2 34 shows the calculated concentration at 3 years in the third layer simulation time 9 467E 07 seconds To generate the breakthrough curves choose Graphs Concentration Time MOC3D from the Tools menu Click on the Plot flags of the Boreholes table until they are set as in Fig 2 35 i Processing Modflow SAMPLE1 PM5 File Value Options Help wj Sap boundary amp m contaminated lin D T i o O C 2 O TH o X a o 4 ap o constant head boundary h no flow boundary 459 1549 594 3662 zb Steady state Recycle H 5 1745 Fig 2 34 Simulated concentration at 3 years in the third layer 2 2 2 Perform Transport Simulation with MOC3D 44 2 3 Automatic Calibration Line Plot X Axis Time Min time Max time 9 467E 07 Ticks n Y AXIS Min value 0 value Ticks Data Types Calculated Iv Observation Options Draw horizontal grid M Draw vertical grid Iv Auto Adjust Graph Style Linear C Semi Log cave Plot As Data gt gt scatter Diagram gt gt Help Close Processing Modflow Fig 2 35 Concentration time curves at the ob
258. he Environment Options dialog box by Options Environment Click the Contours tab check the Visible box and click on the Restore Defaults button to get standard settings Click the Cross Sections tab check the Visible and Show grid boxes and set Exaggeration 25 Projection Row 15 and Projection Column 9 Click on OK to exit the Environment Options dialog box The hydraulic head contours for layer 3 and cross sections showing the location of the particles should appear To set up the particle tracking parameters open the Particle Tracking Time Properties dialog box by Options Particle Tracking Time In the Tracking Steps group change the time unit to years step length to 10 and maximum number of steps to 200 Click OK to exit the Particle Tracking Time Properties dialog box Start the backward particle tracking by Run Backward You can easily see that the flowlines intersect with the river in numerous places Fig 6 12 You can produce a plot of the steady state hydraulic heads of Layer 3 and the flowlines by File Save Plot As To run forward particle tracking We will now introduce a contaminant source upstream of Well 2 and see how far the contamination moves through the steady state flow field after 75 100 and 125 years Since the contamination is a surface source we need to place the particles in layer 1 if you 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River 242 Processing Modflow a
259. he Add New Particles dialog box 2 Run a Steady State Flow Simulation 30 Processing Modflow W PMPATH sample1 pm5 File Options Help E T 8 m contaminated area se E ow ed ae EZ EA l2 1 LA PEE UA 5 Af l s kA i TORNY E P470 2 927470 a 1 qd ee y constant head boundary h EH boundary TEED 2243 3377 0 1 T1 a Fig 2 17 The capture zone of pumping well with vertical exaggeration 1 amp 3 PMPATH sample1 pm5 Ele Run Options Help x amp amp gt gt no flow boundary EATER Oe ET LII 277 79 4 RR RR i ESN z L EIL ETAPA ras Dr oe M P must n w EE P2747 STVA EERE EE 7 Eb ELT constant head bou a qi pt C mn Ul no flow boundary SSS ESS Fig 2 18 The capture zone of the pumping well with vertical exaggeration 10 2 1 Run a Steady State Flow Simulation Processing Modflow 31 3 PMPATH sample1 pm5 Particle Tracking Time Properties Fig 2 20 The Particle Tracking Time Properties dialog box 2 1 Run a Steady State
260. he Steady State is selected in the Simulation Flow Type box Click OK to leave the Time Parameters dialog box Initial hydraulic heads The groundwater flows naturally under a gentle gradient towards the river from both sets of hills and also in an easterly direction The values of starting heads which include the required values for the fixed head cells are saved in the file pm5NexamplesMutorialsXutorial IX2sh dat v zo xu D x To load the initial hydraulic heads Select Parameters Initial Hydraulic Heads Open the Browse Matrix dialog box by Value Matrix In the Browse Matrix dialog box select Load to open the Load Matrix dialog box Click on LJ and select the file pm5 examples tutorials tutorial1 t2sh dat to load Now click on OK Exit the Load Matrix dialog box by clicking on OK The data will appear in the Browse Matrix dialog box click on OK to exit this dialog box and return to the Data Editor The data is now loaded into layer 1 Turn on layer copy by pressing down the layer copy button Move to the second layer and the third layer by pressing PgDn twice Now the data of layer 1 is copied to the second and third layers Leave the Data Editor by File Leave Editor gt Yes Hydraulic Conductivity To set the horizontal hydraulic conductivity Select Parameters gt Horizontal Hydraulic Conductivity Use Value gt Reset Matrix to enter the following data Layer 1 5 0 m day Layer2 0 5 m day Layer3 2 0
261. he cell bottom a GHB cell may not be a fixed head cell and should not be an inactive cell a STR cell may not be a fixed head cell and should not be an inactive cell a well cell may not be a fixed head cell and should not be an inactive cell Processing Modflow 111 3 6 2 Subgrid Within the finite difference grid used to solve the flow equation in MODFLOW the user may specify a window or subgrid over which MOC3D will solve the solute transport equation This feature can significantly enhance the overall efficiency of the model by avoiding calculation effort where it is not needed However MOC3D requires that within the area of the transport subgrid row and column discretization must be uniformly spaced that is Ax and Ay must be constant although they need not be equal to each other The spatial discretization or rows and columns beyond the boundaries of the subgrid can be nonuniform as allowed by MODFLOW to permit calculations of head over a much larger area than the area of interest for transport simulation Vertical discretization defined by the cell thickness can be variable in all three dimensions However large variability may adversely affect numerical accuracy For details refer to Konikow et al 1996 for the model assumptions that have been incorporated into the MOC3D model The subgrid is defined in the Subgrid for Transport MOC3D dialog box Fig 3 34 MOC3D assumes that the concentration outs
262. he mouse 2 Ifyou have several zones some zones can intersect or even cover other zones If you move the mouse cursor into a covered zone the boundary of the zone will not be highlighted In this case you can move the mouse cursor into that zone hold down the Ctrl key and press the left mouse button once The Data Editor will resort the order of the zones and the lost zone will be recovered 3 2 3 Specification of Data for Transient Simulations If your model has more than one stress period a Temporal Data dialog box appears after clicking the leave editor button This dialog box allows you to manage your model data for transient simulations 1 You can edit model data for a particular stress period by selecting a row of the table and clicking the Edit Data button After having specified the model data of a stress period the Data flag in the corresponding row is checked 2 You may click on a Use flag to check or uncheck it If the Use flag is checked the data of the corresponding stress period will be used for the flow simulation If the Use flag is not checked the data of the previous stress period will be used The Use flag of a stress period is automatically deactivated if the corresponding model data are not available 3 Use Copy Data if you want to copy model data from one stress period to another Fig 3 9 shows an example in which the data for the periods 1 3 4 are specified The specified data of the first period will
263. he solver If specified as 0 the program will calculate the value as the product of the two smallest grid dimensions which is an upper limit gt Head change closure criterion L If iterating iteration stops when the absolute value of head change at every node is less than or equal to this value The criterion is not used when not iterating but a value must always be specified Direct Solution DE45 iteration Parameters Maximum Iterations external or internal 500 0 Max equations in upper part of A jo Max equations in lower part of A jo Mexbandwidthof AL 0 Head change closure criterion L Relaxation Acceleration Parameter 1 Printout from the Solver Problem Type All available information C The number of iterations only C None Norndinear Printout Interval 1 Cancel Help Fig 3 29 The Direct Solution DE4S dialog box C Linear gt Printout From the Solver If the option All available information is selected the maximum head change and residual positive or negative are saved in the run record file OUTPUT DAT for each iteration of a time step whenever the time step 15 an even multiple of Printout Interval If the option The number of iterations only is checked the printout of maximum head change and residual 1s suppressed Select the option None to suppress all printout from the solver A positive integer 1s required by Printout Interval
264. he strongly implicit method as applied to the solution of two dimensional groundwater flow equations Water Resour Res 17 4 1082 1086 Leake S A and Prudic D E 1991 Documentation of a computer program to simulate aquifer system compaction using the modular finite difference ground water flow model U S Geological Survey Leonard B P 1979 A stable and accurate convective modeling procedure based on quadratic upstream interpolation Computer Methods Appl Mech Engng 19 p 59 Leonard B P 1988 Universal Limiter for transient interpolation modeling of the advective transport equations the ULTIMATE conservative difference scheme NASA Technical Memorandum 100916 ICOMP 88 11 Leonard B P and H S Niknafs 1990 Cost effective accurate coarse grid method for highly convective multidimensional unsteady flows NASA Conference Publication 3078 Computational Fluid Dynamics Symposium on Aeropropulsion April 1990 Leonard B P and H S Niknafs 1991 Sharp monotonic resolution of discontinuities without clipping of narrow extrema Computer amp Fluids 19 1 p 141 154 Li Y H and 5 Gregory 1974 Diffusion of ions in seawater and in deep sea sediments Pergamon Press Math ron G 1963 Principles of geostatistics Economic Geology 58 1246 1266 McDonald M and W Harbaugh 1988 MODFLOW A modular three dimensional finite difference ground water flow model U S Geological Survey Open file report 53 875
265. he subgrid and dispersion and retardation factor Relative position of initial particles Observation wells Strong Weak flag Observation wells Strong Weak flag Specified concentration of injection wells shared with MT3D Specified concentration at general head boundary cells shared with MT3D Specified concentration of river shared with MT3D Specified concentration of recharge flux shared with MT3D Specified concentration of injection wells shared with MT3D Specified concentration at general head boundary cells shared with MT3D Specified concentration of river shared with MT3D Specified concentration of recharge flux shared with MT3D Description Concentraion of species 1 to 30 associated with the recharge Concentraion of species 1 to 30 associated with the evapotranspiration First sorption constant of species 1 to 30 Second sorption constant of species 1 to 30 First order rate constant for the dissolved phase of species 1 to 30 First order rate constant for the sorbed phase of species 1 to 30 Specified concentration of species 1 to 30 at constant head cells Specified concentration of species 1 to 30 at general head boundary cells Specified concentration of species 1 to 30 associated with injection wells Specified concentration of species 1 to 30 associated with river cells Specified concentration of species 1 to 30 associated with stream cells Flag indicates a Time variant sp
266. head h 10 m Analogous to the 6 2 2 Use of the General Head Boundary Condition Processing Modflow 240 riverbed hydraulic conductance eq 3 21 the hydraulic conductance term of each GHB cell is C K A L where is the horizontal hydraulic conductivity L is the distance from the actual fixed head boundary to the modelled GHB cell and A is the area of the cell face which is perpendicular to the groundwater flow in the un modelled area For this example C T 10 100 10 1000 0 001 m s Fig 6 19 shows the calculated contours For comparison the entire aquifer is modelled with the east and west fixed head boundaries and the result is shown in Fig 6 20 The model is saved in the folder pm5 examples basic basic2a 10 8____ 11 5 11 11 0 uc N 00 5 e D cO _ D 00 LO N D 00 N lt t N E T q T C Ca c cC v Fig 6 20 Calculated head contours for the entire aquifer 6 2 2 Use of the General Head Boundary Condition 250 Processing Modflow 6 2 3 Simulation of a Two Layer Aquifer System in which the Top Layer Converts between Wet and Dry Folder pm5 examples basicWoasic3 Overview of the Problem This example is the first test problem of the BCF2 package McDon
267. hese two parameters are pl and p2 Table 6 4 shows the optimized parameter values and the correlation coefficient matrix calculated by PEST A similar result obtained by UCODE is shown in Table 6 5 The diagonal elements of the correlation coefficient matrix are always unity The off diagonal elements are always between and 1 The closer an off diagonal element is to or 1 the more highly correlated are the parameters corresponding to the row and column numbers of that element For this example transmissivity parameter p1 and recharge parameter p2 are highly correlated as is indicated by the value 0 9572 of the correlation coefficient matrix This means that these parameters are determined with a high degree of uncertainty in the parameter estimation process A sensitivity analysis could be used to quantify the uncertainty in the calibrated model caused by uncertainty in the estimates of the aquifer parameters For our example the only discharge is to the river and the only source is recharge To be in steady state these two must balance Recharge must therefore be equal to 1 125 cfs the river gain equals 11 125 cfs 10 cfs Spreading over the modeled area 3 recharge nes 2x10 ft s 6 1 15 x 15 500 x 500ft The estimated parameter values are acceptable A better procedure would have been to compute the recharge right away from eq 6 1 and calibrate only transmissivity Table 6 4 Optimized parameter values
268. ide of the subgrid is the same within each layer so only one concentration value is specified for each layer within or adjacent to the subgrid by using the C Outside of Subgrid table of this dialog box The values of other layers which are not within or adjacent to the subgrid are 1gnored m Subgrid for Transport MOC3D subqrid C Outside of Subgrid Number of first layer tor transport Number of last layer for transport Number first row far transport Number of last row for transport ERN Number of first column for transport Number last column for transport Cancel Help Fig 3 34 The Subgrid for Transport MOC3D dialog box 3 6 2 MOC3D 112 Processing Modflow MOC3D Initial Concentration MOC3D requires initial concentration of each cell within the transport subgrid at the beginning of a transport simulation The values specified here are shared with MT3D MOC3D Advection Use the Parameter for Advective Transport MOC3D dialog box Fig 3 35 to specify the required data as described below gt Interpolation scheme for particle velocity In MOC3D the advection term of a solute transport process is simulated by the Method of Characteristics MOC Using the MOC scheme a set of moving particles 1s distributed in the flow field at the beginning of the simulation A concentration and a position in the Cartesian coordinate system are associated with each of th
269. ied Concentration ML This value is the concentration in the cell from the beginning of a stress period In a multiple stress period simulation a constant concentration cell once defined will remain a constant concentration cell during the simulation but its concentration value can be specified to vary in different stress period To change the concentration value in a particular stress period simply set a non zero value to Flag and assign the desired concentration value to Specified Concentration In a multispecies simulation the Flag is applied to all species If the constant concentration condition does not apply to a particular species assign a negative concentration value for the species The negative value is used by MT3DMS to skip assigning the constant concentration for the designated species MT3DMS gt Mass Loading Rate Instead of specifying a source concentration associated with a fluid source the mass loading rate MT into the groundwater system can directly be specified by using this menu item MT3DMS Solver gt GCG MT3DMS includes a general purpose iterative solver based on the generalized conjugate gradient method for solving the system of the transport equations The solver is implemented in the Generalized Conjugate Gradient package A detailed description of the method can be found in Zheng and Wang 1998 If this solver is activated 1 e the menu item is checked you can uncheck the item by selecting it
270. ime s 1 Fig 2 42 The Animation dialog box 2 4 Animation Processing Modflow 33 3 The Modeling Environment PMWIN requires the use of consistent units throughout the modeling process For example if you are using length L units of meters and time T units of seconds hydraulic conductivity will be expressed in units of m s pumping rates will be in units of m s and dispersivity will be in units of m A toolbar with buttons representing PMWIN operations or commands is displayed below the menus The toolbar 1s a shortcut for the pull down menus To execute one of these shortcuts move the mouse cursor over the toolbar button and click on it In the following sections the use of the respective menus will be described in detail Some of this information has already been given in Chapter 2 however this chapter is a complete reference of all menus and dialogs in PMWIN therefore some repetitions may occur PMWIN contains the following menus File Grid Parameters Models Tools Value Options and Help The Value and Options menus are available only in the Grid Editor and Data Editor environment PMWIN uses an intelligent menu system to help you control the modeling process If you have specified a model data set the corresponding item of the Grid Parameters and Models menus will be checked To deactivate a selected item 1n the Models menu just seleted the item again If you do not know which model data still need to
271. in rapid succession Although the animation process requires relatively large amount of computer resources to read process and display the data the effect of a motion picture 1s often very helpful The Presentation tool is used to create animation sequences The following steps show how to use the Environment Options and Animation dialog boxes to create an animation sequence for displaying the motion of the concentration plume in the third layer v To create an animation sequence Choose Presentation from the Tools menu Move to the third layer by pressing PgDn twice Choose Environment from the Options menu Click the Contours tab clear Display contour lines and check Visible and Fill Colors Click the table header Level A Contour Levels dialog box appears Set Minimum to 100 Maximum to 1600 and pa ox e don Interval to 100 These values are used because we already know the range of the concentration values from Fig 2 27 When finished click OK to close the dialog box 6 Click the table header Fill A Color Spectrum dialog box appears Set an appropriate color range by clicking the Minimum color and Maximum color buttons When finished click OK to close the dialog box Click OK to close the Enviroment Options dialog box Choose Animation from the File menu The Animation dialog box appears Fig 2 42 9 Click the open file button a A Save File dialog box appears Select or specify a file name in the dia
272. in the K index corresponds to a decrease in elevation z PMPATH always displays the model grid parallel to the Worksheet while PMWIN allows a user to shift and rotate a model grid by giving the rotation angle and the coordinates Xo Yo of the upper left corner of the grid The relation between the model grid and the real world x V Z coordinate system is illustrated in Fig 4 5 The Worksheet displays the plan view of the current model layer and the projection of pathlines on the horizontal IJ plane The cross section windows display the projection of pathlines on the IK and JK planes The Environment Options dialog box of PMPATH see sec 4 3 allows the user to change the appearance of these windows The projection of pathlines on the cross sections 1s useful when running PMPATH with a three dimensional multi layer flow field One should always keep in mind that only the projections of pathlines are displayed The projection of a pathline may be intersected by another or even itself particularly if a three dimensional flow field or a transient flow field is used Status bar The Statusbar displays the following messages the current position of the mouse cursor in both x y 2 coordinates and J I K indices the hydraulic head at the cell J I K the average horizontal pore velocity at the center of the cell J I K the average vertical pore velocity at the center of the cell J I K the current stress period of the f
273. in the cell 6 12 6 5 4 Cut off Wall 290 Processing Modflow penetrating in the first model layer with a pumping rate of 0 0025 m s This low pumping rate is possible because of the low groundwater flow velocity within the zone around the contaminated area Plan view EE L 4 MEN d E uw o il a T o He T D E ru cell width 50 m 25 20 25 amp 50 m Cross section 1 5m K 2 0E 4 m s 8 7 0E 5 m s 10 m 12 18 6 0 4 m s 35 oc impervious Fig 6 53 Model grid and boundary conditions 6 5 4 Cut off Wall Processing Modflow 291 Fig 6 54 Plan and cross sectional views of flowlines Particles are started from the contaminated area The depth of the cut off wall 1s 8 m Ww Y ioc vf 29 ail am p Fig 6 55 Plan and cross sectional views of flowlines Particles are started from the contaminated area The depth of the cut off wall is 10 m 6 5 4 Cut off Wall 202 Processing Modflow 6 5 5 Compaction and Subsidence Folder pm5 examples geotechniques geod Overview of the Problem Fig 6 56 shows a plan view and a cross section through an aquifer which consists of three stratigraphic units of uniform thickness The first unit of the aquifer is unconfined and the other units are confined Th
274. inted Sensitivities are scaled by the parameter value divided by 100 resulting in numbers with the dimensions of the observations 4 Both dimensionless and one percent scaled sensitivities are printed List of Calibration Parameters UCODE LX Convergence criterion changes sum of squared residual SOSR Maximum number of regression iterations Maximum fractional parameter change MAX CHANGE Differencing Method Use forward differencing to calculate sensitivities Use central differencing to calculate sensitivities Apply quasi Newton update when the sum of squared weighted residuals changes less than 0 01 overthree regression iterations Fig 3 56 Control data of UCODE UCODE Inverse Modeling Run To start a model calibration with UCODE select this menu item The available settings of the Run UCODE dialog box Fig 3 57 are described below gt Modflow Version and Modflow Program Several variants of MODFLOW are included in PMWIN PMWIN automatically installs the executables of these variants Their full paths and filenames are given in table 3 4 If you want to use a compiled version located in an other 3 6 6 UCODE Inverse Modeling Processing Modflow 159 position click the open file button E and select the desired code from a dialog box The User s own version must be selected 1f you want to use your own version of MODFLOW Re
275. ional animation sequences using the simulation results calculated heads drawdowns or concentration At present PMWIN supports seven additional packages which are integrated with the original MODFLOW They are Time Variant Specified Head CHD 1 Direct Solution DE45 Density DEN1 Horizontal Flow Barrier HFBI Interbed Storage IBS1 Reservoir RES 1 and Streamflow Routing STR1 The Time Variant Specified Head package Leake et al 1991 was developed to allow constant head cells to take on different values for each time step The Direct Solution package Harbaugh 1995 provides a direct solver using Gaussian elimination with an alternating diagonal equation numbering scheme The Density package Schaars and van Gerven 1997 was designed to simulate the effect of density differences on the groundwater flow system The Horizontal Flow Barrier package Hsieh and Freckleton 1992 simulates thin vertical low permeability geologic features such as cut off walls that impede the horizontal flow of ground water The Interbed Storage package Leake and Prudic 1991 simulates storage changes from both elastic and inelastic compaction in compressible fine grained beds due to removal of groundwater The Reservoir package Fenske et al 1996 simulates leakage between a reservoir and an underlying ground water system as the reservoir area expands and contracts in response to changes in reservoir stage The Streamflow Routing package Prudic
276. ions for the PMWIN MODFLOW PEST interface are specified in the List of Calibration Parameters PEST dialog box Fig 3 53 The avaliable settings are grouped under five tabs described below Using the Save or Load button you can save or load the settings gt Parameters The table gives an overview of the initial values and properties of each estimated parameter The meaning of each column of the table 1s describen below 3 6 5 PEST Inverse Modeling 142 Processing Modflow Number While editing a certain aquifer property or excitation you have the option to define the extent of an estimated parameter by assigning a unique parameter number to the cells of interest That unique parameter number corresponds to the Number here Active The value of an estimated parameter will only be adjusted if Active is checked Otherwise the user specified cell value will be used for the simulation Normally the total number of active parameters should not exceed 10 although PMWIN allows 150 parameters Description A text describing the estimated parameter can be entered here optional for example Transmissivity in layer 3 A maximum of 120 characters is allowed PARVALI is a parameter s initial value For a fixed parameter this value remains invariant during the optimization process For a tied parameter see PARTRANS below the ratio of PARVALI to the parent parameter s PARVALI sets the ratio between these two parameters to b
277. is on when the relief of the button is sunk 3 The Grid Editor Processing Modflow 59 3 2 The Data Editor The Data Editor is used to assign parameter values to the model cells To start the Data Editor select a corresponding item from the Grid Parameters or Models menu For example if you want to assign horizontal hydraulic conductivity to model cells you will choose Horizontal Hydraulic Conductivity from the Parameters menu The Data Editor provides two display modes local and real world and two input methods cell by cell and zonal In the local display mode the display is zoomed to the model grid as shown in Fig 3 5 In the real world display mode the entire worksheet is displayed Fig 3 6 Similar to the the Grid Editor you can adjust the coordinate system the extent of the worksheet and the positon of the model grid to fit the real world coordinates of your study site by using the Environment Options dialog box see section 3 9 Regardless of the choice of the display modes the mouse position x y in the status bar is always expressed in the real world coordinates When the Data Editor is loaded it displays the plan view of the first model layer You can move to another layer by pressing PgDn or PgUp keys or click the Current Layer edit field in the tool bar type the new layer number and press Enter A summary of the tool bar buttons 1s given in the table 3 3 Table 3 3 Summary of the tool bar buttons for the D
278. it must be calibrated prior to use as a predictive tool Calibration is accomplished by finding a set of parameters boundary conditions and excitations or stresses that produce simulated heads or drawdowns and fluxes that match measurement values within an acceptable range of error Model calibration can be performed by the hand operated trial and error adjustment of aquifer parameters or by inverse models such as PEST UCODE MODINV Doherty 1990 or MODFLOW P Hill 1992 This example provides an exercise in model calibration with PEST and UCODE Specific details of this example are from Andersen 1993 Fig 6 35 shows the idealized flow system and locations of observation bores The flow system is a small confined aquifer which is strongly controlled by the river which is flowing across it The aquifer is approximately 100 ft thick and is composed primarily of silty sand The river is not in direct hydraulic connection with the aquifer but acts as a leaky boundary condition which can gain or lose water to the aquifer Stage data for the river and riverbed elevation are listed in Table 6 2 Other boundary conditions are no flow which surround the square and define the areal extent of the aquifer Given constraints of uniform transmissivity and recharge and additional data below obtain a steady state calibration based on the measurements listed in Table 6 3 Initial hydraulic head 100 0 ft grid size 2 15x 15 Ax Ay 500 ft river b
279. iteration During any one optimization iteration PEST tries lots of parameter sets and will consider that the eoal of the iteration has been achieved if PHIRATSUF 3 53 i 1 3 6 5 PEST Inverse Modeling 148 Processing Modflow where is the lowest objective function calculated for optimization iteration 1 1 and hence the starting value for the i th optimization iteration and Q is the objective function corresponding to a parameter set during optimization iteration 1 A value of 0 3 is often appropriate for PHIRATSUF If it is set too low model runs may be wasted in search of an objective function reduction which it is not possible to achieve If it 1s set too high PEST may not be given the opportunity of refining lambda in order that its value continues to be optimal as the parameter estimation process progresses PHIREDLAM is the second criterion for moving to the next optimization iteration If the first criterion PHIRATSUF cannot be achieved during an optimization iteration PEST uses PHIREDLAM to decide when it should move on to the next iteration If the relative reduction in the objective function between the use of two consecutive parameter sets 1s less than PHIREDLAM PEST moves to the next iteration 1 1 That 15 Miu 9 PHIREDLAM 3 54 q where is the objective function value calculated during the i th iteration using the j th trial parameter set A suitable value for PHIREDLAM is
280. itional packages for graphical representations of the simulation results 4 1 The Semi analytical Particle Tracking Method Assume that the density of groundwater is constant Consider a unit volume of a porous medium as shown in Fig 4 2 and apply Darcy s law and the law of conservation of mass The three dimensional form of the partial differential equation for transient groundwater flow in saturated porous media can be expressed as Vox Vey W g 9h 4 1 Ox 2 et where Vs Vs and V L T are values of the specific discharge or Darcy velocity through the unit volume along the x y and z coordinate axes w 1 is a volumetric flux per unit volume and represents internal sources and or sinks of water S is the specific storage of saturated porous media h L is the hydraulic head and t T 1s time For a three dimensional finite difference cell as shown in Fig 4 3 the finite difference form of eq 4 can be written as Q i M i 0 i W S Ah 4 2 Ay A2 Ax Ax A2 Ay AxAykAz AxAyAz Mt p 4 1 The Semi analytical Particle Tracking Method Processing Modflow 177 where Q4 Q5 and Q7 L T are volume flow rates across the six cell faces Ax Ay and Az L are the dimensions of the cell in the respective coordinate directions W L T is flow to internal sources or sinks within the cell and Ah L is the change in hydraulic head o
281. ity 0 0023 m s Storage coefficient 0 00075 Pumping rate 4 x 10 m s Total simulation time 86400 s Number of time steps 20 Time step multiplier 2 1 3 Number of SIP iteration parameters 5 Convergence criterion of head change 0 0001 m Maximum number of iterations 50 6 4 3 The Theis Solution Transient Flow to a Well in a Confined Aquifer Processing Modflow Zu Modeling Approach and Simulation Results To meet the requirement of an infinite areal extent the modelled domain is chosen fairly large The boundary could alternatively be moved even further from the pumping well by using the General Head Boundary see section 6 2 2 The aquifer 1s simulated by a single layer model An increasing grid spacing expansion is used to extend the model boundaries Fig 6 39 The layer type is 0 confined In the Layer Options dialog box the flags of Transmissivity and Storage Coefficient are set to User specified The top and bottom elevations of the model layer are not required The analytical drawdown values at the borehole are specified in the Boreholes and Observations dialog box Both the analytical and calculated drawdown curves are shown in Fig 6 40 An exact comparison is not attained because of the approximations made in the numerical model These include 1 use of a discrete rather than continuous spatial domain 2 use of a discrete rather than continuous time domain 3 use of an iterative solution with a convergence t
282. iven in Appendix 2 Initial Hydraulic Heads MODFLOVW requires initial hydraulic heads at the beginning of a flow simulation Initial hydraulic heads at fixed head cells will be kept constant during the flow simulation For transient flow simulations the initial heads must be the actual values For steady state flow simulations the initial heads are starting guessed values for the iterative equation solvers The heads at the fixed head cells must be the actual values while all other initial heads can be set arbitrarily For an unconfined layer layer type 1 or 3 the initial hydraulic head of a fixed head cell must be higherthan the elevation of the cell bottom because MODFLOW does not convert a dry fixed head cell to an inactive cell If any constant head cell becomes dry MODFLOW will stop the flow simulation and write a message CONSTANT HEAD CELL WENT DRY SIMULATION ABORTED into the run record file OUTPUT DAT Both MT3D and MOC3D require initial concentration at the beginning of a transport simulation Initial concentration at constant concentration cells will be kept constant during the simulation Constant concentration cells can be used to simulate contaminated areas with a fixed concentration Note that the constant concentration boundary condition is not implemented in MOC3D Boreholes and Observations The options of the Boreholes and Observations dialog box are grouped under two tabs Boreholes and Observations gt Borehol
283. kage MTRCT1 dialog box Fig 2 24 The last step before running the transport model is to specify the output times at which the calculated concentration should be saved gt specify the output times 1 Choose MT3D gt Output Control from the Models menu An Output Control MT3D MT3DMS dialog box appears The options in this dialog box are grouped under three tabs Output Terms Output Times and Misc 2 Click the Output Times tab then click the header Output Time of the empty table An Output Times dialog box appears Enter 3000000 to Interval in this dialog box then click OK to accept the other defalut values 3 Click OK to close the Output Control MT3D MT3DMS dialog box Fig 2 25 Dispersion Package MT3D rau need to specify the following values far each layer When finished click OF to specify the longitudinal dispersit L for each cell Horizontal transverse dispersivity Longitudinal dispersivity TREY Vertical transverse dispersivity Longitudinal dispersivity DMCOEF The effective molecular diffusion coefficient L 2 T OK Cancel Help Fig 2 23 The Advection Package MTADV1 dialog box 2 2 1 Perform Transport Simulation with MT3D 36 Processing Modflow Chemical Reaction Package MTRCT1 x Type of Sorption TT Simulate the radioactive decay or biodegradation RHOB is the bulk density of the porous medium in the aquifer M L 3 Kd is th
284. l pm5 c pmSdata samplel sample1 Lx Starting Column 5 Starting Row 5 Ending Column 25 Ending Row 24 Type in the starting and ending columns and rows then Click the Convert button to start the conversion The converted model will be saved in c pmbdata samplel pm5_1 Refinement factor for columns Convert Close Refinement factor for rows Fig 3 11 Telescoping a flow model using the Convert Models dialog box Model Information The Model Information dialog box Fig 3 12 provides brief information about your model You can type a simulation title into the dialog The maximum length of the simulation title 1s 132 characters Save Plot As Use Save Plot As to save the contents of the worksheet in graphics files Fig 3 13 Three graphics formats are available Drawing Interchange File DXF Hewlett Packard Graphics Language HP GL and Windows Bitmap DXF is a fairly standard format developed by 3 3 The File Menu Processing Modflow 67 Autodesk for exchanging data between CAD systems HP GL 1s a two letter mnemonic graphics language developed by Hewlett Packard These graphics formats can be processed by most graphics or word processing software and graphics devices To save a plot use the Format drop down box to select a graphic format Then enter a filename into the File edit field or click and select a file from a dialog box When finished click OK Note that
285. l hydraulic conductivity The mean horizontal hydraulic conductivity of the aquifer is equal to 4 x 0 0001 6 x 0 0005 10 3 4 x 10 m s The standard deviation is assumed to be F 0 5 A correlation length of 60 m is used In chapter 2 the pumping rate of the well was determined such that the contaminated area lies within the capture zone of the well When different realizations of the heterogeneous distribution of hydraulic conductivity are introduced it is obvious that the capture zone not always covers the entire contaminated area The safety criterion for the measure can be defined as the percentage of the covered area in relation to the entire contaminated area The expected value of the safety criterion can be obtained from stochastic simulation Modeling Approach and Simulation Results Using the Field Generator lognormal distributions of the horizontal hydraulic conductivity are generated and stored in ASCH Matrix files First each generated realization is imported into the horizontal hydraulic conductivity matrix then a flow simulation is performed The capture zone of the pumping well as well as pathlines are computed with PMPATH The resulting safety criterion is obtained by a Monte Carlo simulation This implies that many realizations of the parameter field are produced and used in the flow simulation Fig 6 68 shows results of five realizations and the calculated mean safety criterion The 6 7 2 An Example of Stochasti
286. l unit number on the computer being used can be specified except units 97 99 Unit 99 is used for the name file and for reading arrays using the OPEN CLOSE option see Input Instructions for Array Reading Utility Modules section Units 97 and 98 are used for batch files as explained below Each file must have a unique unit number FNAME is the name of the file which is a character value Notes 1 If you want to import a model into PMWIN all files listed in the Name File must be located in the same folder as the Name File itself 2 Although MODFLOW allows array values of some packages BAS BCF EVT and RCH to be saved in extra data files by using DATA BINARY or DATA these features are not supported by the converter of PMWIN You must put the external array values into the package files before converting the model 3 Animported model will have the same model name as the Name File Example of a Name File This example file is generated by PMWIN for the model located in pm5 examples basic basic1 The file name is basic1 nam LIST 6 output dat BAS 1 bas dat BCF 11 bcf dat OC 22 oc dat Appendix 3 Input Data Files of the supported Models 316 Processing Modflow WEL 12 wel dat RCH 18 rch dat PCG 23 pcg2 dat DATA BINARY 50 budget dat DATA BINARY 51 heads dat DATA BINARY 52 ddown dat DATA BINARY 32 mt3d flo MODFLOW BASIC PACKAGE RTI C ate ook Be es ee oe Bee BAS DAT Block Centered Flow Package 0
287. lated Use this menu item to open the Chemical Reaction Package MTRCTI dialog box Fig 3 44 to specify the required parameters on a layer by layer basis The parameters are described below Chemical Reaction Package MTRCT1 Type of Sorption Simulate the radioactive decay or biodegradation 0 000125 0 000125 RHOB is the bulk density of the porous medium in the aquifer M L 3 Kd is the distribution coefficient L 3 M SF is not used and are not used OK Cancel Help Fig 3 44 The Chemical Reaction Package MTRCT1 dialog box gt of sorption Sorption is implemented in MT3D through use of the retardation factor R MT3D provides three types of sorptions the linear equilibrium isotherm Freundlich nonlinear equilibrium isotherm and Langmuir nonlinear equilibrium isotherm The linear sorption isotherm assumes that the sorbed concentration ix 18 directly proportional to the dissolved concentration C eq 3 41 and the retardation factor is independent of the concentration field The retardation factor is calculated only once for each cell at the beginning of the simulation by eq 3 42 Ci Ky Ci ik 3 41 p Rc 1 3 42 ik 3 6 3 Processing Modflow 127 where n is the porosity of the porous medium in the cell j 1 Ky L M is the distribution coefficient that depends on the so
288. lation of Lower layer gt Storage Coefficient For transient flow simulations MODFLOW requires dimensionless storage terms to be specified for each model layer For a confined layer these storage terms are given by the confined storage coefficient specific storage 11 x layer thickness L If the Storage Coefficient flag is set to Calculated PMWIN uses user specified specific storage coefficients and the elevations of the 3 4 The Grid Menu 72 Processing Modflow top and bottom of each layer to calculate the confined storage coefficient Set the Storage Coefficient flag to User Specified if you want to specify the confined storage coefficient manually For an unconfined layer the storage values are equal to specific yield The setting of the Storage Coefficient flag has no influence on the specific yield gt Interbed Storage PM WIN supports the Interbed Storage package for calculating storage changes from both elastic and inelastic compaction of each model layer Check the flag of a layer if you want to use the Interbed Storage package see Models Menu for details about this package gt Density Check the flag of a layer if you want to use the Density package to simulate the effect of density differences on the groundwater flow system Density effect can only be applied to layers of type 0 or 2 See Models Menu for more information about the Density package
289. layer 1 6 2 5 Simulation of a Perched Water Table 260 Processing Modflow 6 2 6 Simulation of an Aquifer System with Irregular Recharge and a Stream Folder pm5 examples basic Woasice Overview of the Problem This example is the first test problem of the Streamflow Routing STR1 package Results from the STR1 Package were compared to results from an analytical solution developed by Oakes and Wilkinson 1972 An idealized aquifer with a river flowing through the middle was chosen and is shown in Fig 6 26 The width of the aquifer perpendicular to the river was 4 000 ft on each side while the length parallel to the river was 13 000 ft Assumptions used in both the analytical solution and the model simulation include 1 The lateral boundaries of the aquifer are impermeable no flow is allowed The rocks beneath the aquifer are impermeable The river penetrates the entire depth of the aquifer and has vertical banks The river is not separated from the aquifer by any confining material ois get 19 The transmissivity and storage coefficient are constant throughout the aquifer and remain constant in time The aquifer is confined and Darcy s Law is valid The flow of groundwater is horizontal The water level in the river is constant along its length and with time pL DS ehh The infiltration of recharge to the aquifer is instantaneous no delay between the time precipitation infiltrates the surface until it reaches the water tabl
290. ld is required for layers of type 1 2 and 3 Refer to Spitz and Moreno 1996 for a summary of values of specific yield Refer to Bear 1972 1979 or Freeze and Cherry 1979 for more information about the storage terms and their definitions 3 5 The Parameters Menu 80 Processing Modflow 3 6 The Models Menu 3 6 1 MODFLOW MODFLOW Density Using the Density package Schaars and van Gerven 1997 the water density of a density layer may differ from cell for cell During a flow simulation the density dependent flows will be adapted into the system of flow equations by correcting the hydraulic heads to equivalent fresh water heads or reference density heads It is assumed that the density distribution and the internodal transmissivities remain constant during a flow simulation Therefore density layers may only be used in combination with layers of the types O or 2 confined A density layer is marked by using the Layer Options dialog box Note that the Density package is not a real density flow model It is only an approximation which 15 valid as long as flow processes do not change the salinity distribution considerably The density package requires the input of a reference density which is normally set to the density of freshwater and the density distribution within the density layers These values are specified by using the Data Editor Reference density REFRHO ML and Cell Density ML 7 Note that the Density pa
291. le PESTCTL REC This file 1s saved in the data directory of your model It tabulates the optimal values and the 95 confidence intervals pertaining to all adjustable parameters It also tabulates the model calculated values based on these parameters together with the residuals 1 e the differences between measured and model calculated values If you wish PEST will write the parameter covariance matrix the parameter correlation coefficient matrix and the matrix of normalised eigenvectors of the covariance matrix to the run record file PESTCTL REC If the option Save data for a possible restart is checked PEST will dump the contents of many of its data arrays to a binary file at the beginning of each optimization iteration this allows PEST to be restarted later 1f execution 1s prematurely terminated If subsequent PEST execution is initiated using the r command line switch see the PEST manual for details it will recommence execution at the beginning of the iteration during which it was interrupted If the option Include decimal point even if redundant is not checked PEST will omit the decimal point from parameter values on model input files if the decimal point is redundant thus making room for the use of one extra significant figure If this option 1s checked PEST will ensure that the decimal point 1s always present 3 6 5 PEST Inverse Modeling 152 Processing Modflow PEST Inverse Modeling Run To start a model calibration
292. librium controlled linear or non linear sorption and first order irreversible decay or biodegradation MT3DMS is a further development of MT3D The abbreviation MS denotes the Multi Species structure for accommodating add on reaction packages MT3DMS includes three major classes of transport solution techniques 1 the standard finite difference method the particle tracking based Eulerian Lagrangian methods and the higher order finite volume TVD method In addition to the explicit formulation of MT3D MT3DMS includes an implicit iterative solver based on generalized conjugate gradient GCG methods If this solver 1s used dispersion sink source and reaction terms are solved implicitly without any stability constraints The MOC3D transport model computes changes in concentration of a single dissolved chemical constituent over time that are caused by advective transport hydrodynamic dispersion including both mechanical dispersion and diffusion mixing or dilution from fluid sources and mathematcally simple chemical reactions including decay and linear sorption represented by a retardation factor MOC3D uses the method of characteristics to solve the transport equation on the basis of the hydraulic gradients computed with MODFLOW for a given time step This implementation of the method of characteristics uses particle tracking to represent advective transport and explicit finite difference methods to calculate the effects of other processes For
293. ll be discharged If the sink is weak flow will be into the cell from some cell faces and a part of flow will leave the cell through another faces A particle entering such a cell may be discharged or may leave the cell again In the finite difference approach however it 1s impossible to determine whether that particle should be discharged or pass through the cell If this option is selected particles will be discharged when they enter cells with internal sinks regardless of the flow condition 2 Particles stop when the simulation time limit is reached This option is only available if the simulation mode Pathlines use transient flow fields is selected In PMPATH the starting time of each particle is always the beginning of the time step defined in Current Time For the forward particle tracking scheme the simulation time limit 1s the end of a transient flow simulation For the backward particle tracking scheme on the other hand the simulation time limit is the beginning of the simulation Backward particle tracking will not work if this stop option is checked and particles are started from the beginning of a transient flow 4 3 PMPATH Options Menu Processing Modflow 193 simulation In this case particles will be stopped immediately after the start Note that you cannot start backward particle tracking from the end of a transient flow simulation rather you can only start particles from the beginning of the last simulation time step
294. ll conditioned 6 7 1 Using the Field Interpolator Processing Modflow 303 Fig 6 64 Contours produced by Shepard s inverse distance method 6 7 Using the Field Interpolator 304 Processing Modflow Fig 6 66 Contours produced by Akima s bivariate interpolation 6 7 1 Using the Field Interpolator Processing Modflow 305 Fig 6 67 Contours produced by Renka s triangulation algorithm 6 7 1 Using the Field Interpolator 306 Processing Modflow 6 7 2 An Example of Stochastic Modeling Folder pm5 examples misc misc2 Overview of the Problem Aquifer remediation measures are often designed by means of groundwater models Model results are usually uncertain due to the imperfect knowledge of aquifer parameters We are uncertain about whether the calibrated values of parameters represent the real aquifer system We never know the actual small scale distribution of some parameters e g hydraulic conductivity or recharge Thus all groundwater models involve uncertainty Stochastic models are often employed to take into account uncertainty In the stochastic modeling approach the model parameters appear in the form of probability distributions of values rather than as deterministic sets We use the aquifer described in chapter 2 to illustrate the concept of stochastic modeling Using a two dimensional approach to model the aquifer we may utilize the Field Generator to create lognormal correlated distributions of the horizonta
295. log box then click Open 10 Check Create New Frames set Result Type to Concentration MT3D and set Display Time s to 0 1 Display Time is the display duration for each frame 11 In the Animation dialog box click OK to start the animation 2 4 Animation 52 Processing Modflow PMWIN will create a frame image for each time point at which the simulation results here concentration are saved Each frame is saved using the filenames fn xxx where fn is the Frame File specified in step 9 and xxx is the serial number of the frame files Note that if you have complex DXF basemaps the process will be slowed down considerably When all frames are created PMWIN will repeat the animation indefinitely until the Esc key 15 pressed Once a sequence is created you can playback the animation at a later time by repeating steps 8 to 11 with Create New Frames cleared in step 10 You can also use the Animator to playback the sequence Note that the number and the size of the image files can be very large Make sure that there 1s enough free space on your hard disk To reduce the file size you can change the size of the PMWIN window before creating the frames You may turn off the display of the model grid in the Environment Options dialog box so that you don t have the grid cluttering the animation Frame File Click the open file button to select a file r Frames Create New Frames Result Type Hydraulic Head Display T
296. low Version MODFLOW96 INTERFACE TO 6 AND LATER Madflow Program e program fles pm5 mocdthw4b 2 exe e B jBesicPeckego cApmbdeteisemplelibasdet Options Regenerate all inputfiles for MODFLOW Check the model data Generate input files only don t start MODFLONV M Don t generate MODPATH files anyway Cancel Help Fig 2 7 The Run Modflow dialog box 2 1 Run a Steady State Flow Simulation Processing Modflow 19 Table 2 1 Output files from MODFLOW File Contents path OUTPUT DAT Detailed run record and simulation report path HEADS DAT Hydraulic heads path DDOWN DAT Drawdowns the difference between the starting heads and the calculated hydraulic heads path BUDGET DAT Cell by Cell flow terms path INTERBED DAT Subsidence of the entire aquifer and compaction and preconsolidation heads in individual layers path MT3D FLO Interface file to MT3D MT3DMS This file is created by the LKMT package provided by MT3D MT3DMS Zheng 1990 1998 path is the folder in which the model data are saved Table 2 2 Volumetric budget for the entire model written by MODFLOW VOLUMETRIC BUDGET FOR ENTIRE MODEL AT END OF TIME STEP 1 IN STRESS PERIOD L 3 T CONSTANT HEAD 209690 CONSTANT HEAD 2150E 03 WELLS 0 WELLS 0 0000 RECHARGE 254472 RECHARGE 6880E 03 IOTAL IN 464163 TOTAL IN 9030E 03 OUT OUT CONSTANT HEAD 350533 CONSTANT HEAD 7027E 03 WELLS 113604 WELLS
297. low simulation the current time step of the flow simulation and pa caecum qu cbe the number of particles See Particle Tracking Time Properties dialog box sec 4 3 for how to change the current stress period and time step The hydraulic heads at the current stress period and time step are calculated by MODFLOW The average horizontal pore velocity at the center of a cell is obtained by averaging the velocities V 4 Vx2 and vy Vy respectively see equation 4 3a 4 3d The average vertical pore velocity at the center of a cell is the average of the velocities V V see equation 4 3e and 4 3f The vertical velocity 15 defined as positive when it points in the k direction 4 2 PMPATH Modeling Environment 182 Processing Modflow vertical local coordinate for setting particles current layer z PMPATH example pm5 BEI Es File Bun Options Help x amp amp lt of 2 IT lin E 5 jection i mM I II OLOSE E l is i OLIS e i d rm Dl Ji bl eT S o T LO t i ection of pathiines 4 Vf 4 m
298. lp 1 From the Help menu choose Search You can also click the Search button from any Help topic window 2 In the Search dialog box type a word or select one from the list by scrolling up or down Press ENTER or choose Show Topics to display a list of topics related to the word you specified 3 Select a topic and press ENTER or choose Go To to view the topic Context Sensitive Help Many parts of the PMWIN Help facility are context sensitive Context sensitive means you can access help on any part of PMWIN directly by clicking the Help button or by pressing the F1 key Updates Today the development of groundwater modeling techniques is progressing very rapidly and a groundwater model must periodically be updated and expanded For updates of PMWIN and our other software you may access the following web pages on the Internet http www uovs ac za igs index htm http www baum ethz ch inw soft welcome html 1 Introduction 6 Processing Modflow FOR YOUR NOTES 1 Introduction Processing Modflow 7 2 Your First Groundwater Model with PMWIN It takes just a few minutes to build your first groundwater flow model with PMWIN First create a groundwater model by choosing New Model from the File menu Next determine the size of the model grid by choosing Mesh Size from the Grid menu Then specify the geometry of the model and set the model parameters such as hydraulic conductivity effective porosity etc Finally perfor
299. lts should be loaded If the orientation is Plan View you are asked to enter a layer number into the edit field If X section column or X section row is selected you should enter a column or row number into the edit field next to drop down box Column Width This drop down box is used to change the appearance width of the columns of the speadsheet Tabs Each tab corresponds to a simulation model The tabs are described below MODFLOW The result files of MODFLOW include hydraulic head drawdown preconsolidation head compaction subsidence and cell by cell flow terms see MODFLOW gt Output Control of section 3 6 1 for the definition of each term You can choose a result type from the Result Type drop down dox The stress period and time step from which the result 1s read are given in the corresponding edit fileds MOC3D The result files of MOC3D include concentration and velocity terms You can choose a result type from the Result Type drop down dox The simulation time from which the result is read can be selected from the Total Elapsed Time drop down box This drop down box is empty if the selected simulation result does not exist MT3D The primary result of MT3D is concentration If you are using MT3D96 two additional result types 1 e solute mass and sorbed mass can be selected The simulation time from which the result is read can be selected from the Total Elapsed Time drop down box This drop down box is empty
300. lues that are not used must be specified as zero The following table gives the assignment of the parameters in the Value l vector Refer to section 3 6 1 for the definitions of the parameters Package Value 1 Value 2 Value 3 Value 4 WEL1 Recharge rate XXX XXX XXX DRN1 Hydr conductance Elevation XXX XXX RIV1 Hydr conductance Head in river Elevation XXX EVT1 Max ET rate ET Surface Extinction Depth Layer Indicator GHB1 Hydr conductance Head at boundary XXX XXX RCH1 Recharge Flux Layer Indicator XXX XXX HFB1 Barrier Direction K Thickness XXX XXX IBS1 Preconlidation head Elastic storage Inelastic storage Starting compaction CHD1 Flag Start head End head XXX The values used by the STR1 package are Value 1 Segment Value 2 Reach Value 3 StreamFlow Value 4 Stream stage Value 5 Hydr conductance Value 6 Elavation of the streambed top Value 7 Elavation of the streambed bottom Value 8 Stream width Value 9 Stream slope Value 10 Manning s roughness coefficient divided by C are the x y coordinates of the J th node of the zone The first and the last node must overlap Appendix 2 Files and Formats Processing Modflow 315 Appendix 3 Input Data Files of the supported Models The following tables gives the name of input data files for each packages of the supported models The input files are saved in the same folder as the model data Refer to the documentation of corresponding models for the fo
301. lustrated in Fig 3 63 the worksheet is a window to the real world your model grid is placed within the worksheet The extent and location of the worksheet are defined by specifying the real world coordinates of its lower left and upper right corners 1 e by the coordinates Y and Y as shown in Fig 3 63 and Fig 3 64 The location and orientation of the model grid are defined by the coordinates X Yo of its left upper corner and a rotation angle The rotation angle is expressed in degrees and is measured counterclockwise from the positive x direction gt Contours The Data Editor displays contours based on the cell data The Contours tab allows you to control the display of the contour levels labels and colors The options of this tab are listed below Visible Contours are visible if this box is checked Display contour lines Contour lines and labels are displayed if this box is checked Fill contours Checking this box causes the space between contour lines to be filled with the color defined in the contour level table 3 9 The Options Menu Processing Modflow 167 Orient label uphill If this box is checked the contour labels are displayed so that they are always oriented uphill 1 e oriented to places with higher cell values x 8 M 1 4 7 2 3 E ji id QR n 19 it Hy ur aT 3 LM D T E Ld i ur n L 4 NK 3 y N
302. lute species nature of the porous medium and other conditions of the system and ML is the bulk density of the porous medium The bulk density is the ratio of the mass of dried soil to total volume of the soil The Freundlich isotherm is a non linear isotherm which can be expressed in eq 3 43 The retardation factor at the beginning of each transport step 1s calculated by eq 3 44 C C 3 43 _ Pp a 1 K 1 wd a K 3 44 jik where C is the solute concentration in the cell in the cell j 1 k at the beginning of each transport step a is the Freundlich exponent and K L M is the Freundlich constant The Langmuir non linear sorption isotherm is described by eq 3 45 The retardation factor at the beginning of each transport step 1s calculated by 3 46 K S C ik 3 45 TERK C ik K S Rui 3 46 GODS Cid where K L M is the Langmuir constant and S MM is the maximum amount of the solute that can be adsorbed by the soil matrix For more information on the mathematical description of adsorption and transport of reactive solutes in soil the user can refer to Travis 1978 or Bear and Verruijt 1987 gt Simulate the radioactive decay or biodegradation Check this box to simulate the effect of the first order irreversible rate reactions The concentration change due to the chemical reaction from one transport step to another transport st
303. ly any obvious signs in the output from a simulation that does not use external iteration to indicate that iteration is needed In particular the budget error may be acceptably small without iteration even though there 1s significant error in head because of non linearity To understand this consider the water table correction for transmissivity Each iteration a new transmissivity 1s calculated based on the previous head Then the flow equations are solved and a budget is computed using the new head with the same transmissivities No budget discrepancy results becuase heads are correct for the transmissivity being used at this point however the new heads may cause a significant change in transmissivity The new transmissivity will not be calculated unless there is another iteration Therefore when one or more layers is under water table conditions iteration should always be tried The maximum change in head during each iteration printed by the solver provides an indication of the impact of all non linearities MODFLOW Solvers PCC2 The required parameters for the PCG2 package are specified in the Preconditioned Conjugate Gradient Package 2 dialog box Fig 3 30 They are described below Preconditioning Method The PCG2 package provides two preconditioning options the modified incomplete Cholesky preconditioner MICCG Axelsson and Lindskog 1986 and the Neuman Series Polynomial preconditioner POLCG Saad 1985 gt Relaxati
304. m day 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River 238 Processing Modflow 3 Leave the Data Editor by File Leave Editor Yes gt To set the vertical hydraulic conductivity Select Parameters Vertical Hydraulic Conductivity 2 Use Value Reset Matrix to enter the following data for each layer Layer 1 0 5 m day Layer2 0 05 m day Layer3 1 0 m day 3 Leave the Data Editor by File Leave Editor gt Yes Effective Porosity The effective porosity is used in PMPATH which we will use later to define the capture zones of the pumping wells gt specify the effective porosity Select Parameters Effective Porosity 2 Use Value Reset Matrix to enter the following data for each layer Layer 1 0 2 Layer2 0 25 Layer3 0 25 3 Leave the Data Editor by File Leave Editor Yes Hiver The River data is a little difficult to set up MODFLOW requires that the river stage ie head river bottom elevation and riverbed conductance be specified The riverbed conductance is defined as Give SES M where hydraulic conductance of the riverbed L T K hydraulic conductivity of the riverbed sediment L T L length of the river within a cell L W width of the river within a cell L M thickness of the riverbed L 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River Processing Modflow 239 In our case the riverbed has the following p
305. m the flow simulation by choosing MODFLOW gt Run from the Models menu After completing the flow simulation you can use the modeling tools provided by PMWIN to view the results to calculate water bugdets of particular zones or graphically display the results such as head contours You can also use PMPATH to calculate and save pathlines or use the finite difference transport models MT3D or MOC3D to simulate transport processes This chapter provides an overview of the modeling process with PMWIN describes the basic skills you need to use PMWIN and takes you step by step through a sample problem A complete reference for all menus and dialog boxes in PMWIN is contained in Chapter 3 The advective transport model PMPATH and the modeling tools are described in Chapter 4 and Chapter 5 respectively Overview of the Sample Problem As shown in Fig 2 1 an aquifer system with two stratigraphic units is bounded by no flow boundaries on the North and South sides The West and East sides are bounded by rivers which are in full hydraulic contact with the aquifer and can be considered as fixed head boundaries The hydraulic heads on the west and east boundaries are 9 m and 8 m above reference level respectively The aquifer system is unconfined and isotropic The horizontal hydraulic conductivities of the first and second stratigraphic units are 0 0001 m s and 0 0005 m s respectively Vertical hydraulic conductivity of both units is assumed to be 10
306. m underground nuclear explosives J Geophys Res 64 1509 1519 Hill M C 1990a Preconditioned Conjugate Gradient 2 PCG2 A computer program for solving groundwater flow equations U S Geological Survey Denver Hill M C 1990b Solving groundwater flow problems by conjugate gradient methods and the strongly implicit procedure Water Resour Res 26 9 1961 1969 8 References 330 Processing Modflow Hill M C 1992 MODFLOW P A computer program for estimating parameters of a transient three dimensional groundwater flow model using nonlinear regression U S Geological Survey Open file report 91 484 Hill M C 1998 Methods and guidelines for effective model calibration U S Geological Survey Water Resources Investigations Report 98 4005 Hoschek J and D Lasser 1992 Grundlagen der geometrischen Datenverarbeitung B G Teubner Stuttgart Germany Hsieh P A 1986 A new formula for the analytical solution of the radial dispersion problem Water Resour Res 22 11 1597 1605 Hsieh and Freckleton 1993 Documentation of a computer program to simulate horizontal flow barriers using the U S Geological Survey s modular three dimensional finite difference ground water flow model U S Geological Survey Open File Report 92 477 Hunt B 1983 Mathematical analysis of groundwater resources Butterworths Cambridge Javandel C Doughty and Tsang 1984 Groundwater transport Handbook of m
307. m values found in the current layer After having made your changes and clicked on OK the contour levels in the table are updated to reflect the changes Line and Fill define the color of a contour line and the fill color between two contour lines Clicking on one of the headers the Color Spectrum dialog box Fig 3 66 appears Using this dialog box the contour colors can be automatically assigned to produce a gradational change from a minimum color to a maximum color To change the minimum or maximum color simply click on the button and select a color from a Color dialog box After clicking on OK a gradation of colors from the minimum to the maximum is assigned to each contour level Label Using the Contour Labels dialog box Fig 3 67 you can define the display frequency of contour labels First labeled contour line defines the first contour line to be labeled Labeled line frequency specifies how often the contour lines are labeled After having made your changes and clicked on OK the flags in the table is updated to reflect the changes you specified You can click on an individual cell of the label column to turn label on or off Label height specifies the appearance height of the label text It uses the same length unit as the model Label spacing specifies the distance between two contour labels It uses the same length unit as the model Label Format The Label Format dialog box Fig 3 68 allows you to specify the f
308. ment of particles by specifying a negative number to NP T PND pressing the Tab key and entering local particle coordinates into table in the lower part of the dialog box shown in Fig 3 35 where PNEWL PNEWR and PNEWC are relative positions for the initial placement of particles in the layer row and column direction respectively The local coordinate system range is from 0 5 to 0 5 and represents the relative distance within the cell about the node location at the center of the cell so that the node is located at 0 0 in each direction Parameters for Advective Transport MOC3D Interpolation scheme for particle velocity Bilinear XY directions Maximum number of particles NPMAX 50000 Courant number CELDIS 45 Fraction limit for regenerating initial particles FZERO De Initial number of particles per cell NPTPND 4 PNEWL PNEWR PNEWC 1 _ 0 25 0 25 0 25 EE 0 25 0 25 Cancel Help Fig 3 35 The Parameters for Advective Transport MOC3D dialog box 3 6 2 MOC3D 114 Processing Modflow MOC3D Dispersion amp Chemical Reaction The types of reactions incorporated into MOC3D are restricted to those that can be represented by a first order rate reaction such as radioactive decay or by a retardation factor such as instantaneous reversible sorption desorption reactions governed by a linear isotherm and constant distribution coefficient Use the Dispersion Che
309. menu or press Ctrl R A Reset Matrix dialog box appears 3 Enter 10 in the dialog box then click OK 2 Run a Steady State Flow Simulation 14 Processing Modflow The elevation of the top of the first layer is set to 10 Move to the second layer by pressing PgDn Repeat steps 2 and 3 to set the top elevation of the second layer to 6 and the top elevation of the third layer to 3 Choose Leave Editor from the File menu or click the leave editor button ge To specify the elevation of the bottom of model layers Choose Bottom of Layers BOT from the Grid menu Repeat the same procedure as described above to set the bottom elevation of the first second and third layers to 6 3 and 0 respectively Choose Leave Editor from the File menu or click the leave editor button ge We are going to specify the temporal and spatial parameters of the model The spatial parameters for sample problem include the initial hydraulic head horizontal and vertical hydraulic conductivities and effective porosity To specify the temporal parameters Choose Time from the Parameters menu A Time Parameters dialog box will come up The temporal parameters include the time unit and the numbers of stress periods time steps and transport steps In MODFLOW the simulation time is divided into stress periods 1 e time intervals during which all external excitations or stresses are constant which are in turn divided into time steps In most t
310. mical Reaction MOC3D dialog box Fig 3 36 to specify the required data for each model layer as described below gt Simulate Dispersion Check this option if dispersion should be included in the simulation First order decay rate T typically represents represents radioactive decay of both the free and sorbed solute A radioactive decay rate is usually expressed as a half life t The half life is the time required for the concentration to decrease to one half of the original value is calculted by Ine 2 A 3 32 gt Effective molecular diffusion coefficient L T describes the diffusive flux of a solute in water from an area of greater concentration toward an area where it is less concentrated The mass flux is proportional to the concentration gradient and 1s given by Fick s first law ac F D where ML T is the mass flux of solute per unit area per unit time D L T is the diffusion coefficient ML is the solute concentration and dC dx ML L is the concentration gradient In porous media the solute mass cannot diffuse as fast as in free water because the ions must move along longer pathways through the pore space and because of adsorption on the soil matrix To account for this tortuosity effect an effective diffusion coefficient D must be used D 0 D 3 34 According to Freeze and Cherry 1979 w ranges from 0 5 to 0 01 for laboratory studies of diffusion of nonadsorbed
311. more than a value of 4 0 again MAX CHANGE times the parameter value and the new value will be between 2 0 and 6 0 This maximum change is applied to the physical parameter value not its log transformed value Exceptions are discussed in Hill 1998 Appendix B MAX CHANGE 2 0 is common but smaller values may help an oscillating regression to converge Differencing method controls the method used to calculate sensitivities during the parameter estimation iterations Starting with the forward differencing method is recommended Apply quasi Newton update when sum of squared weighted residuals changes less than 0 01 over three regression iteration According to Hill 1998 applying the quasi 3 6 6 Inverse Modeling 158 Processing Modflow Newton update may facilitate convergence of highly nonlinear problems gt Options Print residuals and sensitivities for intermediate iterations When it is checked the residuals and sensitivities will be printed saved for intermediate iterations in the output file UCODE ot Scale Sensitivities Controls the scaling applied to the printed sensitivities Four options are available 1 No scaling unscaled sensitivities are printed 2 Dimensionless scaled sensitivities are printed Sensitivities are scaled by the parameter value times the square root of the weight resulting in dimensionless numbers Composite scaled sensitivities also are printed 3 One percent scaled sensitivities are pr
312. mputed or observed data The graph viewer uses solid lines for displaying calculated curves Observation curves are dashed Options Check the Draw Horizontal Grid or Draw Vertical Grid box to display the reference grids on the graph If Auto Adjust Min Max is checked the graph viewer uses the minimum and maximum simulation times and values from the simulation result Graph Style You can display the time axis X axis either on a linear or logarithmic scale Save Plot As Use this button to save the graph in Windows bitmap format Data Click this button to display the Value Tables dialog box Fig 5 10 showing the observed and calculated values at active boreholes Y ou can save the calculated values in ASCII data file or 1n the Observation file format see Appendix 2 for the format by clicking the Save As button Data saved in the Obervation file format can be imported into the Observation table of the Boreholes and Observations dialog box see section 3 5 Scatter Diagramm Click the button to display the Scatter diagram dialog box Fig 5 11 Scatter diagrams are often used to present the quality of calibration results The observed values are plotted on one axis against the corresponding calculated values on the other If there is exact agreement between measurement and simulation all points lie on a 45 line The narrower the area of scatter around this line the better is the match Note that a borehole will be dis
313. n PM5 L GRD C97 Z97 83 Z83 WBL WEZ POL PPL UPL TRN TRS TMP 1 ASCII ASCII ASCII CBC ZONE CBC ZONE CBC ZONE BINARY BINARY BINARY BINARY BINARY Description Most options and settings of a model are saved in this file Settings of the Layer options Grid Specification file see Appendix 2 for the format Digitizer Digitizer Presentation Presentation subregions for the calculation of water budget subregions for the calculation of water budget contains boreholes and observations saved automatically by PMWIN parameter list for PEST saved automatically by PMWIN parameter list for UCODE saved automatically by PMWIN is a time parameter file saved automatically by PMWIN is a Trace file saved automatically by PMWIN RESERVED for internal use RESERVED for internal use Appendix 4 Internal Data Files of PMWIN 324 Processing Modflow Appendix 5 Using PMWIN with your MODFLOW PMWIN supports various versions of MODFLOW by using different IUNIT assignments as shown in Table 7 1 These IUNIT assignments must be the same as those used in the main program of your own version of MODFLOW see Table 7 2 for an example In the Run Modflow dialog box you may select any MODFLOW version to use with your own MODFLOW program as long as the IUNIT assignments match the default values shown in Table 7 1 Table 7 1 Default settings of the IUNIT assignments MODFLOW MODFLOW MODFLOW 88 Package
314. n any one prior information equation If a parameter 1s log transformed you must provide prior information pertinent to the log to base 10 of that parameter The parameter name must be placed in brackets and preceded by log note that there is no space between log and the following opening bracket Care must be used here because PMWIN does not check the prior information equation However you can use the program PESTCHEK Doherty et al 1994 included in PMWIN to check the PEST data To the right of the sign of each prior information equation are two real variables PIVAL and WEIGHT The former is the value of the right hand side of the prior information 3 6 5 PEST Inverse Modeling Processing Modflow 147 equation The latter is the weight pertaining to the article of prior information in the parameter estimation process The weight should be inversely proportional to the standard deviation of the prior information value PIVAL it can be zero if you wish but not be negative The following lines show some examples refer to Doherty et al 1994 for more details on the prior information In PMWIN the parameter name of the first parameter is The parameter name of the second parameter is P2 and so on 1 0 log P1 1 2 log P2 5 6 1 0 1 0 P1 1 455 P2 3 98 2 123 P4 1 03E 3 2 00 2 12 P8 3 2 P6 1 344 2 20 gt Control Data The control data are used to set internal array dimensions of PES
315. n be divided into three parts The first two chapters introduce PMWIN with an example Chapters 3 through 5 are a detalied description of the building blocks Chapter 3 describes the use of Processing Modflow chapter 4 describes the advection model PMPATH and chapter 5 introduces the modeling tools provided by Processing Modflow The third part Chapter 6 provides two tutorials and documents the examples Beside this text we have gathered about 3 000 pages of documents related to the supported models It is virtually not possible to provide all the documents in a printed form So we decided to present these documents in an electronic format The advantage of the electronic documents is considerable with a single CD ROM you always have all necessary documents with you and we save resources by saving valuable papers and trees Many many people contributed to this modeling system The authors wish to express heartfelt thanks to researchers and scientists who have developed and coded the simulation programs MODFLOW MOC3D MT3D MT3DMS PEST UCODE Without their contributions Processing Modflow would never have its present form Many thanks are also due to authors of numerous add on packages to MODFLOW We wish to thank many of our friends and colleagues for their contribution in developing checking and validating the various parts of this software We are very grateful to Steve Bengtson John Doherty Maciek Lubczynski Wolfgang Schafer Udo Qu
316. n each flow time step The subsequent transport stepsize may increase or remain constant depending on the user specified transport stepsize multiplier see below If the transport step size is specified as zero the model calculated value based on the user specified Courant number in the Advection Package MT3DMS dialog box is used gt Max No of Transport Steps is used by MT3D and MT3DMS If the number of transport steps within a flow time step exceeds the maximum number the simulation is terminated gt Multiplier Transport is the multiplier for successive transport steps within a flow time step This value is only used by MT3DMS for the case that the Generalized Conjugate Gradient solver and the upstream finite difference method are selected gt Simulation Time Unit Each time you select a time unit from the Simulation Time Unit group PMWIN will update the period length in the table if Auto Update Period Length is checked gt Simulation Flow Type PMWIN allows you to perform steady state or transient flow simulations by selecting an option from the Simulation Flow Type group You can run a 3 5 The Parameters Menu 76 Processing Modflow steady state simulation over several stress periods In this case a steady state solution is calculated for each stress period gt Save and Load Using these buttons you can save or load the contents of the table in or from a time parameter file The format of the time parameter file is g
317. n within the mining site is turned off PlanView 95m open cast mining site 2000 m E 5 o 2 E E TS Fixed head boundary h Cross section open cast mining site Fig 6 32 Plan view of the model area 6 2 8 Simulation of Lakes Processing Modflow 267 Modeling Approach and Simulation Results The aquifer 1s simulated using five model layers 21 rows and 25 columns The thickness of each model layer is 20 m The elevation of the top of the first model layer is 100m A regular grid spacing of 100 m is used for each column and row The layer type 3 confined unconfined transmissivity varies is used for every layer For task 1 the cells within the mining site in the 4th model layer are set as fixed head cells with the initial hydraulic head of 21m The cells of all 5 layers at the west boundary are fixed head cells with the initial head h 2 100m The cells of the layers 3 to 5 at the east boundary are fixed head cells with the initial head h 2 50m The initial hydraulic head at all other cells has been set at 100m To ensure that there is no resistance to the groundwater flow within the mining site a very high value say 1 m s is used for the vertical and horizontal hydraulic conductivities of the cells within the site A steady state flow simulation was performed Fig 6 33 shows
318. nal structure to the horizontal hydraulic conductivity Choose Horizontal Hydraulic Conductivity from the Parameters menu Move to the third layer by pressing PgDn twice Choose Reset Matrix from the Value menu or press Ctrl R A Reset Matrix dialog box appears Enter 1 to the Parameter Number edit box then click OK The horizontal hydraulic conductivity of the third layer is set to the parameter 1 Choose Leave Editor from the File menu or click the leave editor button pel Note that for layers of type 0 confined and 2 confined unconfined transmissivity const MODFLOW reads transmissvity instead of hydraulic conductivity from the model data file consequently we are actually calibrating the transmissivity and must use suitable values for the initial guess and lower and upper bounds Change the layer type to 3 confined unconfined transmissivity varies if you want to calibrate the horizontal hydraulic conductivity To specify the coordinates of the observation boreholes and measured values Choose Boreholes and Observations from the Parameters menu and enter the coordinates of the observation boreholes into the boreholes table Click the Observations tab and enter the values into the observations table as shown in Fig 2 36 Note that the observation time to which the measurement pertains is measured from the beginning of the model simulation For a steady state simulation with one stress period you can run a steady state sim
319. nce models Ground Water 26 6 743 750 Pollock D W 1989 MODPATH version 1 x Documentation of computer programs to compute and display pathlines using results from the U S Geological Survey modular three dimensional finite difference ground water model U S Geological Survey Open file report 89 381 Pollock D W 1994 User s guide for MODPATH MODPATH PLOT version 3 A particle tracking post processing package for MODFLOW the U S Geological Survey finite difference ground water flow model Reston VA U S Geological Survey Prudic D E 1988 Documentation of a computer program to simulate stream aquifer relations using a modular finite difference grund water flow model U S Geological Survey Open File Report 88 729 Carson City Nevada Rausch 1998 Computer program for the calculation of 1 D and 2 D concentration distribution Personal communication Renka R J 1984a Interpolation of the data on the surface of a sphere ACM Transactions on Mathematical Software 10 417 436 Renka R J 1984b Algorithm 624 Triangulation and interpolation at arbitrarily distributed points in the plane ACM Transactions on Mathematical Software 10 440 442 Robinson R A and Stokes R H 1965 Electrolyte Solutions 2nd ed Butterworth London Saad Y 1985 Practical use of polynomial preconditionings for the conjugate gradient method SIAM Journal of Scientific and Statistical Computing 6 4 865 881 S
320. nd once you become familiar with the commands and menus it is very easy to enter and change the model data The values of the particular data being edited or entered and the selected cell are displayed in the status bar on the bottom of the screen The model data for the task 1 steady state water level with recharge no pumping includes aquifer types flow boundaries aquifer geometry aquifer parameters initial conditions time paramters and recharge rates 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge 220 Processing Modflow Aquifer types Since we only have one layer in the model it is relatively straightforward to define it as unconfined gt define the aquifer type 1 Select Grid Layer Type 2 Inthe Layer Options dialog box click on Type and select Unconfined it is okay to browse through the rest of this dialog box but leave all the values as the default ones 3 Click OK to leave the Layer Options dialog box Flow boundaries MODFLOW uses an array called the IBOUND array to determine if a particular cell 1s active inactive no flow or a fixed head cell Cell values within IBOUND are as follows active 1 or other positive integers inactive 0 fixed head 1 or other negative integers These values are assigned to cells as required in the Data Editor By default and convention the area outside the model domain is deemed to be a No Flow Zone and as such it is not necessary to
321. ndex number The index number 1s positive if the forward particle tracking scheme is used A negative index number indicates that the backward particle tracking scheme is used Global coordinate in the x direction Global coordinate in the y direction Verticle local coordinate within the cell Global coordinate in the z direction Cumulative travel time J index of cell containing the point I index of cell containing the point Sr HE Gee K index of cell containing the point Except the particle index number this format is identical to the PATHLINE FILE format described in the documentation of MODPATH Hydraulic heads To save the hydraulic heads in the current layer at the current stress period and time step select Save Heads As from the File menu PMPATH saves the hydraulic heads in ASCII Matrix format see Appendix 2 Drawdowns To save drawdowns in the current layer choose Save Drawdowns As from the File menu and specify a file name in the standard File Save As dialog box This menu item 15 disabled if the drawdown file DDOWN DAT is not available PMPATH saves the drawdowns in the ASCII Matrix format see Appendix 2 Flow velocities To save flow velocities in the current layer choose Save Velocity As from the File menu and specify a file name in the standard File Save As dialog box Average pore velocities at the center of each cell are saved in the ASCII Matrix format see Appendix 2 In additi
322. nerally a higher flow velocity for example the velocity in the immediate vicinity of a pumping well will cause larger values of D D and D which in turn result in a smaller At in eq 3 38 When At is too small the required CPU time will become enormous To overcome this problem an implicit formulation is implemented in MT3DMS See section 3 6 4 for details Dispersion Package MT3D MT3DMS You need to specify the following values for each layer When finished click OK to specify the longitudinal dispersivity L for each cell TRPT Horizontal transverse dispersivity Longitudinal dispersivity TRPY Vertical transverse dispersivity Longitudinal dispersivity DMCOEF The effective molecular diffusion coefficient L 2 T rRPT TRPV DMCOEF T 07 i OK Cancel Help Fig 3 43 The Dispersion Package MT3D MT3DMS dialog box 3 6 3 MT3D 126 Processing Modflow MT3D gt Chemical Reaction gt Layer by Layer Chemical reactions supported by MT3D include equilibrium controlled sorption and first order irreversible rate reactions such as radioactive decay or biodegradation It is generally assumed that equilibrium conditions exist between the aqueous phase and solid phase concentrations and that the sorption reaction is fast enough relative to groundwater velocity so that it can be treated as instantaneous Consider to use MT3DMS if nonequilibrium rate limited sorption needs to be simu
323. ng the installation of PMWIN Except the tutorials the description of each problem is divided into three parts It starts out with Folder where you can find the ready to run model for example pm5 examples tutorials tutorial1 Next you ll find a discussion of the problem and finally you will find the simulation results Note that you should change the path 5 if you have installed PMWIN in an other folder 6 1 Tutorials 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge Folder pm5 examples tutorials tutorial1 Overview of the Problem This simple scenario 1s designed to demonstrate the basic features of PMWIN and MODFLOW An unconfined aquifer Fig 6 1 1s a coarse grained sand with a measured isotropic hydraulic conductivity of 160 m day the specific yield has been assessed as 0 06 Recharge to the aquifer only occurs throughout the 4 month wet season at a rate of 7 5 x 10 m day outside the wet season there is no recharge to the aquifer The elevations of the aquifer top and bottom are 25 m and 0 m respectively The area of interest is 10000 m long and 6000 m wide and 1s bounded by no flow zones to the east and west There 1s also a volcanic mountain in the south east corner of the model area To the north an area of constant hydraulic head existd with a value of 15 m The southern boundary is a specified flux boundary with an inflow rate of 0 0672 m day per meter A total of nine wells in the area are pumped at 45 1 3
324. ngitudinal dispersivity as shown in Fig 2 23 2 Click OK PMWIN displays the model grid At this point you need to specify the longitudinal dispersivity to each cell of the grid 3 Choose Reset Matrix from the Value menu or press Ctrl R type 10 in the dialog box then click OK Turn on layer copy by clicking the layer copy button 5 Move to the second layer and the third layer by pressing PgDn twice The cell values of the first layer are copied to the second and third layers 6 Choose Leave Editor from the File menu or click the leave editor button pel gt assign the chemical reaction parameters 1 Choose MT3D gt Chemical Reaction gt Layer by Layer from the Models menu A Chemical Reaction Package MTRCTI dialog box appears Clear the check box Simulate the radioactive decay or biodegradation and select Linear equlibrium 2 2 Perform Transport Simulation with MT3D Processing Modflow 35 isotherm for the type of sorption For the linear isotherm the retardation factor R for each cell is calculated at the beginning of the simulation by H 1 K 2 3 Where n is the effective porosity with respect to the flow through the porous medium ML is the bulk density of the porous medium and L M is the distribution coefficient of the solute in the porous medium As the effective porosity is equal to 0 25 setting P 2000 and 0 000125 yields R 2 2 Click OK to close the Chemical Reaction Pac
325. nite difference erid The cell data are shown in the spreadsheet If you are editing a particular package in which a cell has more than one value for example the River package requires three values for each cell you can select the parameter type from the Parameter drop down box The Column Width drop down box is used to change the appearance width of the columns of the spreadsheet You may edit the cell data within the Browse Matrix dialog box You may also assign a value to a group of cells by using the mouse to mark the cells and then enter the desired value You may save the cell data by clicking the Save button and specifying the file name and the file type in a Save Matrix As dialog box There are four file types ASCII Matrix Wrap form ASCII Matrix SURFER files and SURFER files real world An ASCII Matrix file may be loaded into the spreadsheet at a later time The format of the ASCII matrix file 1s described in Appendix 2 A SURFER file has three columns containing the x y coordinates and the value of each cell If the file type 1s SURFER files the origin of the coordinate system for saving the file is set at the lower left corner of the model grid If the file type is SURFER files real world the real world coordinates of each cell will be saved The real world coordinate system 15 defined by Options Environment Paramter Column Width Recharge Flux 14 3 4 5 6 8 09 8 09 8 09 8E 09 2 8 09 8
326. not be placed in inactive cells or fixed head cells constant head cells 4 2 PMPATH Modeling Environment 184 Processing Modflow v To place a group of particles Click the Set particle button Move the mouse cursor to the active model area The mouse cursor turns into crosshairs Place the crosshairs where you want a corner of the Set Particle window Drag the crosshairs until the window covers the subregion over which particles will be placed then release the mouse button The Add New Particles box appears Fig 4 6 Where NI NJ and NK are the number of particles in I J and K directions respectively Using NI NJ and NK particles can be placed either on cell faces or within cells which lie in the Set Particle window These numbers can range from 0 to 999 In the case shown in Fig 4 6 8 particles will be placed within each cell 3 Z3x1 particles will be placed on each cell face and 15 particles will be placed around each cell at a distance of 20 The particles will get the color and the retardation factor given in the Properties tab of this dialog box gt place a single particle Click the Set particle button 2 Change the vertical local coordinate and the particle color for the definition of the vertical local coordinate see equation 4 7 3 Move the mouse cursor to the desired position and click the right mouse button A particle will be placed Note that this particle will have the retarda
327. nter values shown in Fig 2 40 into the table Start value is the initial guess of the parameter Minimum is the reasonable minimum value and Maximum is the reasonable maximum value for the parameter These two values are used solely to determine how the final optimized value of the parameter compares to a reasonable range of values 3 Check the Log transform flag to log transform the parameter This will ensure that only positive values will be used for the parameter during the calibration gt To perform the automatic calibration 1 Choose UCODE Inverse Modeling gt Run from the Models menu The Run UCODE dialog box appears Fig 2 41 2 Click OK to start the calibration Prior to running UCODE PMWIN will use user specified data to generate input files for UCODE and MODFLOW as listed in the table of the Run UCODE dialog box An input file will be generated only if the generate flag is set to EJ You can click on the button to toggle the generate flag between and Generally you do not need to change the flags as PMWIN will care about the settings Check calibration results During the automatic calibration several result files are created Similar to PEST UCODE writes the optimized parameter values to the input files of MODFLOW BCF DAT WEL DAT etc and creates a detailed run record file path ucode _ot where path 1s the folder in which your model data are saved The simulation results of MODFLOW are updated by using the op
328. ntration values will be saved in the unformatted binary file MT3D UCN In addition MT3D96 can save the mass contained in each cell in the unformatted binary file MT3D CBM All output files are located in the same folder as your model You can use the Result Extractor to read the unformatted binary files Output Times The value of the output frequency NPRS indicates whether the output is produced in terms of total elapsed simulation time or the transport step number If NPRS 0 simulation results will only be saved at the end of simulaton If NPRS 0 simulation results will be saved whenever the number of transport steps is an even multiple of NPRS If NPRS 0 simulation results will be saved at times as specified in the table as shown in Fig 3 46 There are two ways for specifying the output times You may click the table header Output Time and then enter a minimum time a maximum time and a time interval between each output into an Output Time dialog box PMWIN will use these entries to calculate NPRS and the output times The other way 1s to specify a positive NPRS and press the Tab Key then enter the output times into the table Note that the output times are measured from the beginning of the simulation 3 6 3 MT3D 130 Processing Modflow gt Misc CINACT is the predefined concentration value for an inactive concentration cell ICBUND 0 THKMIN is the minimum saturated thickness in a cell expressed as the decimal fraction
329. nts found in the entire model The valid range of Data Per Sector is SIMPLE 3 Data Per Sector 30 QUADRANT 1 lt Data Per Sector lt 7 OCTANT 1 lt Data Per Sector lt 3 The search method defaults to OCTANT search Octant or quadrant searches are usually used when the measurement points are grouped in clusters These search methods force the interpolation programs to use measurement data points radially distributed around the model cell They usually introduce more smoothing than a SIMPLE search Note that the entries in Search Method are ignored when Renka s triangulation algorithm is used To start the interpolation simply click the button GO The field generator creates and writes the settings and the coordinates to a batch file PMDIS BAT and two ASCII files PMDIS_IN 1 and PMDIS_IN 2 After having created these files PMDIS BAT will be run in a DOS window The created ASCII files are used by the interpolation program 5 2 The Field Interpolator 206 Processing Modflow Fig 5 5 Search pattern used by a Quadrant Search Data Per Sector 2 and b Octant Search Data Per Sector 1 5 3 The Field Generator The Field Generator Frenzel 1995 can generate fields with heterogeneously distributed transmissivity or hydraulic conductivity This allows the user to do stochastic modeling with PMWIN In stochastic modeling uncertainty due to unknown small scale variability of the model parameters is addressed directly by ass
330. obile domain is the concentration in the immobile domain and T is the first order mass transfer rate between the mobile and immobile domains As the mass transfer rate increases the dual domain model functions more and more like the single domain model with a porosity approaching the total porosity of the porous medium For very small values of the right hand side of eq 3 50 approaches zero i e there 15 no change of the concentration in the immobile domain and the model functions like a single porosity model with the primary effective porosity One of the advantages of this approach is that the fracture structure does not need to be known However a problem may arise when one tries to estimate the mass transfer rate G by measuring the concentrations C and Cn When we measure the concentration at a certain point we only obtain one value and cannot distinguish between mobile and immobile concentration It is therefore more likely that must be estimated through a model calibration using C values 3 6 4 MT3DMS Processing Modflow 137 MT3DMS Sink Source Concentration The use of this menu is the same as MT3D Sink Source Concentration except the use of Time Variant Specified Concentration A time varying specified concentration cell is defined by setting the following data in the Data Editor Flag A non zero value indicates that a cell 1s specified as a constant concentration cell Specif
331. of 9 8925 and 9 m respectively The configuration of the remediation measures is shown in Fig 6 37 The pumping rates of the wells are defined as an estimated parameter by assigning the parameter number 1 to all four wells An observation borehole 1s set at the center of the contaminated area The observed head at time 1 is set at 8 m the remediation objective in the Boreholes and Observations dialog box The simulation time is also set to 1 Using PEST or UCODE the pumping rate of 6 4 2 Estimation of Pumping Rates Processing Modflow 275 each well is estimated at about 7 9x10 m s To calculate the duration until the steady state 1s reached the estimated pumping rate of 7 9x10 is specified to each well A transient simulation with one stress period subdivided into 25 equal time steps is carried out The total simulation time is 1x10 seconds The calculated head time curve Fig 6 38 shows that the steady state is reached at t 4x10 s no flow boundary e o cut off wall fixed head boundary h fixed head boundary h no flow boundary I lt 1785 m Fig 6 36 Plan view of the model E pumping wells cut off wall observation borehole Fig 6 37 Location of the cut off wall and pumping wells Fig 6 38 Head versus time at the center of the contaminated area 6 4 2 Estimation of Pumping Rates 276 Processing Modflow 6 4 3 The Theis Solution Transien
332. of the model layer thickness below which the cell is considered inactive THKMIN will only be used by MT3D96 or later NPRMAS indicates how frequently the mass budget information should be saved in the mass balance summary file MT3D MAS M Concentration unformatted Cell byCell mass unformatted only MT3D96 Conentration ASCII Number of parciles ASCII Ratardation factor ASCII Dispersion coefficient ASCII OK Cancel Help Fig 3 45 The Output Control MT3D MT3DMS dialog box Output Frequency NPRS 33 0 3000000 6000000 9000000 1 2E 0 1 5E 0 1 6E 0 2 1E 0 AF f OK Cancel Help Fig 3 46 Specifying the output times for MT3D Co Po MT3D Run The available settings of the Run MT3D MT3D96 dialog box Fig 3 47 are described below gt MT3D Program contains the full path and filename of the MT3D code which will be called 3 6 3 MT3D Processing Modflow 131 by PMWIN The default code is the version DoD 1 5 developed by Zheng 1996 If you want to use a compiled version located in another position click the open file button and select the desired code from a dialog box gt File Table PMWIN uses the user specified data to generate input files of MT3D Description gives the name of the packages used in the flow model The path and name of the input file are shown in Destination File PMWIN generat
333. olecular diffusion coefficient and decay rate are assumed to be zero We will calculate the concentration distribution after a simulation time of 3 years and display the breakthrough curves concentration versus time at two points X Y 290 310 390 310 in both units no flow boundary 9m 8m pumping well contaminated area pumping well 600 I E c 3 o amp L D X ru fixed head boundary h no flow boundary 580 m Fig 2 1 Configuration of the sample problem 2 1 Run a Steady State Flow Simulation Six main steps must be performed in a steady state flow simulation Create a new model model Assign model data Perform the flow simulation Check simulation results Calculate subregional water budget a M ge MC Produce output 2 Run a Steady State Flow Simulation Processing Modflow 9 Step 1 Create a New Model The first step in running a flow simulation is to create a new model gt create a new model 1 Choose New Model from the File menu A New Model dialog box appears Select a folder for saving the model data such as C PMSDATA SAMPLE and type the file name SAMPLE for the sample model A model must always have the file extension PMS All file names valid under Windows 95 98 NT with up to 120 characters can be used It is a good idea to save every model in a separate folder where the model and its output data will be kept This will also
334. olerance and 4 artificial placement of boundaries In practice you can use this model to estimate transmissivity and confined storage coefficient by specifying the real observation time and data in the Boreholes and Observations dialog box By defining transmissivity and storage coefficient as estimated parameters the inverse models PEST or UCODE can estimate the parameters automatically Click Models PEST gt Run or Models gt Run to see how the inverse models work Because the analytical drawdown values were used as the observations the results from the inverse models must be transmissivity 0 0023 m s and storage coefficient 0 00075 6 4 3 The Theis Solution Transient Flow to a Well in a Confined Aquifer 278 Processing Modflow fixed head boundary pumping er NEE ENE po EQ _ L sereafion Tc fixed head boundary fixed head boundary fixed head boundary Fig 6 39 Configuration of the groundwater model Drawdown Time EU 4 Fig 6 40 Drawdown time curves 6 4 3 The Theis Solution Transient Flow to a Well in a Confined Aquifer Processing Modflow 279 6 4 4 The Hantush and Jacob Solution Transient Flow to a Well in a Leaky Confined Aquifer Folder pm5 Yexamples calibration calibration4 Overview of the Problem This examples demonstrates how to approach leaky confined aquifers A leaky confined aquifer is overlaid and or und
335. ollowed by one blank space P1 P2 Parameter names The parameter name of the first parameter is P1 The parameter name of the second parameter is P2 and so on see examples below amp Indicates that the preceding and following products are to be summed thus it performs like a Stat is a label followed by STAT STAT is a statistic value used to calculate the weight for the prior information For log transformed parameters specify the log transformed statistic even though PVALUE is a decimal value flag is a lable followed by STAT FLAG STAT FLAG isa flag indicating whether STAT is a variance STAT FLAG 0 standard deviation STAT FLAG 1 or coefficient of variation STAT FLAG 2 plot is a label followed by PLOT SYMBOL PLOT SYMBOL is an integer printed in the UCODE output file UCODE ot used for graphical analyses Different values for plot symbol can be used to indicate different types of observations so that they can be differentiated with a unique symbol on a graph The utility of PLOT SYMBOL will depend on the graphical software being used The following lines show some examples refer to Hill 1998 and Poeter and Hill 1998 for 3 6 6 UCODE Inverse Modeling Processing Modflow 157 more details about the use of the prior information P 10 0 5 x P1 amp 0 5 x P2 stat 0 2 flag 2 plot 4 P 1 03E 3 1 0 x P1 amp 1 45 x P2 amp 3 9 x P3 amp 2 123 x P4 stat 2 0 flag 2 plot 3 P 1 344 2 12 x P3
336. omatically assign regularly spaced search ranges to each active row by clicking on one of the headers Minimim or Maximum then enter a minimum and a maximum value to a Search Level dialog box The colors can be automatically assigned so you will get a gradational change from one color to another To do this click the header Color of the table and assign a minimum color and a maximum color to a Color Spectrum dialog box To change the color individually click on the colored cell a l button appears then click on the l button and select a color from a Color dialog box According to the user specified value in the Value column and the operation option in the Options column you can easily modify the cell values The available operations are listed below Display Only No operation takes place Replace The cell values are replaced by the user specified value Add The user specified value 1s added to the cell values Multiply The cell values are multiplied by the user specified value gt Parameter drop down box For particular packages in which a cell has more than one value e g the River package of MODFLOW this drop down box contains the available parameter type s Choose the parameter type for which the Search and Modify operation will apply gt Ignore Inactive Cells If it is checked the Search and Modify operation will only be applied to active cells gt Maps You may display background maps DXF or Line Map
337. on the velocity components along the I J and K axes are added to the end of the file The default velocity at inactive cells is 1 0x10 9 4 4 PMPATH Output Files Processing Modflow 197 Particles To save the position and the attributes of each particle choose Save Particles As from the File menu and specify a file name in a Save Particle As dialog box By selecting a file type in this dialog box you can save either the starting position or end position after backward or forward tracking of each particle The following data format is used to save the particles 1 Data version label 2 Data NP Data LI LJ LK I J 4 R The first line of this particle file contains the version label PMPATH V100 PARTICLES The second line contains the number of particles NP The third record contains one line of data for each particle The particle locations within the cell J I K are specified using local coordinates LJ LI LK Local coordinates vary within a cell from zero to one as shown in Fig 4 14 In addition the global vertical coordinate Z the color C and the retardation factor R of the particle are saved in the same line The particles file can be loaded by choosing Load Particles from the File menu When you load a particle file PMPATH just adds particles to the model Already existing particles will not be removed N X Fig 4 14 Local coordinates within a cell 4 4 PMPATH Out
338. on Mejia s algorithm Institut f r Umweltphysik University of Heidelberg Germany Gelhar L W and M A Collins 1971 General analysis of longitudinal dispersion in nonuniform flow Water Resour Res 7 6 1511 1521 Gelhar L W A Mantaglou C Welty and K R Rehfeldt 1985 A review of field scale physical solute transport processes in saturated and unsaturated porous media EPRI Report EA 4190 Electric Power Research Institute Palo Alto CA Gelhar L W C Welty and K R Rehfeldt Rehfeldt 1992 A critical review of data on field scale dispersion in aquifers Water Resour Res 28 7 1955 1974 Hantush M S and E Jacob 1955 Non steady radial flow in an infinite leaky aquifer Trans Am Geophys Un 36 11 95 100 Harbaugh A W 1995 Direct solution package based on alternating diagonal ordering for the U S Geological Survey modular finite difference ground water flow model U S Geological Survey Open File Report 95 288 46 pp Harbaugh A W and M McDonald 1996a User s documentation for MODFLOW 96 an update to the U S Geological Survey modular finite difference ground water flow model USGS Open File Report 96 485 Harbaugh A W and M G McDonald 1996b Programmer s doumentation for MODFLOW 96 an update to the U S Geological Survey modular finite difference ground water flow model USGS Open File Report 96 486 Higgins G H 1959 Evaluation of the groundwater contaminantion hazard fro
339. on Parameter is used with MICCG Usually this parameter is equal to 1 Ashcraft and Grimes 1988 found out that for some problems a value of 0 99 0 98 or 0 97 will reduce the number of iterations required for convergence gt The option Calculate the upper bound on the maximum eigenvalue is only available when POLCG is selected Check this box if the upper bound on the maximum eigenvalue of A should be calculated by the solver Otherwise a value of 2 will be used The upper bound is estimated as the largest sum of the absolute values of the components in any row of A Convergence is generally insensitive to this value Estimation of the upper bound uses slightly more execution time per iteration 3 6 1 MODFLOW 106 Processing Modflow gt Allowed Iteration Numbers MXITER is the maximum number of outer iterations For each outer iteration A and b eq 3 30 are updated by using the newly calculated hydraulic heads For a linear problem MXITER should be 1 unless more that 50 inner iterations are required A larger number generally less than 100 is required for a nonlinear problem Outer interations continue until the final convergence criteria see below are met on the first inner iteration is the maximum number of inner iterations Eq 3 30 with a new set of A and b is solved in inner iterations The inner iterations continue until ITER1 iterations are executed or the final convergence criteria see below are met gt C
340. on file UCODE PEPA eon acd ac sob gt cioe tape Ae ts ipta aci os tope AU ee apres edes UCODE PRE SI NI Cc UCODE UNI wot C ts Sa C ETE RE E RE AT E E RE EE RE UCODE EXT Block Centered Flow Package Template File BCFTPL DAT Package Template Filo x sewers ES eee oa X dex Ceo OR se Ca PLU xe de d DRNTPL DAT Evapotranspiration Package Template File EVTTPL DAT General Head Boundary Package Template File GHBTPL DAT Recharge Package Template RCHTPL DAT River Package Template RNG ecu acces C oen Ba e e Ca Cede es RIVTPL DAT Well Package Template File ee ee eee eee WELTPL DAT Stream Routing Flow Package Template SIRTPL DAT Interbed Storage Package Template File IBSTPL DAT Grid Specification File used bp MODBORE EXE filename GRD Borehole Listing File used by MODBORE EXE BORELIST DAT Borehole Coordinates File used by MODBORE EXE BORECOOR DAT Appendix 3 Input Data Files of the supported Models 318 Processing Modflow Appendix 4 Internal data files of PMWIN
341. onary and isotropic The Kriging method estimates the value at a model cell from a user specified number of adjacent data values while considering the interdependence expressed in the variogram A variogram is a plot of semivariance Y versus vector distance h The variogram is used to define the relationship of the measurement values or to estimate the distance over which measurement values are interdependent When you select Kriging as the gridding method a Variogram appears Click this button to display the Variogram dialog box Fig 5 3 You need to select a variogram model from the drop down box and specify the parameters for the selected variogram model PMWIN does not provide a procedure for fitting the selected variogram curve to the measurement data This is a task for geostatistical software e g VarioWin Y Pannatier 1996 or GEO EAS E Englund and A Sparks 1991 by the US 5 2 The Field Interpolator 204 Processing Modflow EPA and beyond the objective of this software If you do not know the variogram type use the linear variogram Kriging with a linear variogram is usually quite effective The meaning of necessary parameters and the equations used by the programs are listed below Power law and linear model Yih a h c a gt 0 0 0 2 Logarithmic model Vu 8a log Al a gt 0 Spherical model 3 Von ORE bd hea 2 2g Yi gt Gaussian model Vin 1 EXP
342. onvergence Criteria Head Change L is the head change criterion for convergence When the maximum absolute value of the head change at all nodes during an iteration 15 less than or equal to the specified Head Change and the criterion for Residual is satisfied see below iteration stops Residual LT is the residual criterion for convergence Residual is calculated as b A x for each inner iteration When the maximum absolute value of the residual at all cells during an iteration is less than or equal to Residual and the criterion for Head Change is satisfied see above iteration stops gt Printout From the Solver A positive integer is required by Printout Interval If the option All available information is selected the maximum head change and residual positive or negative are saved in the run record file OUTPUT DAT for each iteration of a time step whenever the time step is an even multiple of Printout Interval If the option The number of iterations only is checked the printout of maximum head change and residual 15 suppressed Select the option None to suppress all printout from the solver Preconditioned Conjugate Gradient Package 2 Preconditioning Method C Neuman Series Polynomial jv Calculate tHe Upnerbound on the maximum Relaxation Parameter 1 Allowed Iteration Numbers Convergence Criteria Outer Iteration MXITER Head Change L 100 001 Inner Iteration
343. or from the Value menu read the head results and use an additional Apply button in the Results Extractor dialog box to put the data into the Presentation matrix Click the Load button The Load Matrix dialog box appears Fig 2 11 Click E and select the file H1 DAT which was saved earlier by the Results Extractor Click OK when ready H1 DAT is loaded into the spreadsheet In the Browse Matrix dialog box click OK The Browse Matrix dialog box is closed Choose Environment from the Options menu or Press Ctrl E The Environment Options dialog box appears Fig 2 12 The options in the Environment Options dialog box are grouped under three tabs Appearance and Coordinate System allow the user to modify the appearance and position of the model grid Use Contours to generate contour maps Click the Contours tab check Visible then click the Restore Defaults button Clicking on the Restore Defaults button PMWIN sets the number of contour lines to 11 and uses the maxmum and minimum values in the current layer as the minimum and maximum contour levels Fig 2 13 If Fill Contours is checked the contours will be filled with the colors given in the Fill column of the table Use Label Format button to specify an appropriate format Note that PMWIN will clear the Visible check box when you leave the Editor 8 9 10 11 In the Environment Options dialog box Click PMWIN will redraw the model and display the contour
344. or their assumptions applicability and limitations Data Editor Maximum number of layers 80 Maximum number of stress periods 1000 Maximum number of cells along rows or columns 2000 Maximum number of cells in a layer 250000 Maximum number of zones in a layer 20 Maximum number of vertex nodes of a zone 40 Maximum number of stream segments 25 Maximum number of tributary segments of each stream segment 10 Maximum number of reservoirs 20 Maxmum number of observated stages of each reservoir 200 There is no limit to the number of wells general head boundary cells rivers drains and horizontal flow barrier cells Boreholes and Observations Maximum number of boreholes 1000 Maximum number of observations 10000 Digitizer Maximum number of digitized points 10000 Field Interpolator Maximum number of cells in a layer 250000 Maximum number of cells along rows or columns 2000 Maximum number of input data points 2000 Field Generator Maximum number of cells in a layer 250000 Maximum number of cells along rows or columns 500 Water Budget Calculator Maximum number of subregions 50 Appendices 310 Processing Modflow Appendix 2 Files and Formats ASCII Matrix File An ASCII Matrix file can be saved or loaded by the Browse Matrix dialog box see section 3 8 The Results Extractor Field Interpolator and Field Generator use this file format to save the generated data File Format 1 Data
345. ore than one model layer In this case the injection or pumping rate for each layer has to be specified The total injection or pumping rate for a multilayer well is equal to the sum of those from the individual layers For confined layers the injection or pumping rate for each layer Q can be approximately calculated by dividing the total rate Qta in proportion to the layer transmissivities McDonald and Harbaugh 1988 T k Q otal s 3 26 where T is the transmissivity of layer and XT is the sum of the transmissivities of all layers penetrated by the multilayer well Another possibility to simulate a multi layer well is to set a very large vertical hydraulic conductivity or vertical leakance e g 1 m s to all cells of the well The total pumping rate is then assigned to the lowest cell of the well For display purposes a very small pumping rate say 1x10 m s can be assigned to other cells of the well In this way the exact extraction rate from each penetrated layer will be calculated by MODFLOW implicitly and the value can be obtained by using the Water Budget Calculator See Chapter 2 for how to calculate subregional water budgets 3 6 1 MODFLOW 98 Processing Modflow MODFLOW Wetting Capability The wetting capability of the Block Centered Flow 2 package BCF2 McDonald et al 1991 allows the simulation of a rising water table into unsaturated dry model layers The BCF2 package is identical to
346. orehole will be shown when the Graphs Viewer is activated Appendix 2 Files and Formats Processing Modflow 311 COLOR is the color used to draw the obervation vs time curve of a borehole The color is defined by a long integer using the equation color red green x 256 blue x 65536 where red green and blue are the color components ranging from 0 to 255 NAME is the name of the borehole Contour Table file A contour table file can be saved or loaded by the Environment dialog box see section 3 8 File Format 1 Data LABEL 2 Data NL XXX XXX XXX XXX The following data repeats NB times 3 Data LEVEL COLOR FILL LVISIBLE LSIZE LDIS XXX XXX XXX Explanation of Fields Used in Input Instructions ALL DATA IN THE SAME RECORD ARE SEPARATED BY A COMMA OR BLANK LABEL is the file label It must be PMWIN5000 CONTOUR FILE NL is the number of contour levels XXX reserved LEVEL Contour level COLOR is the color used to draw the contour line The color is defined by a long integer using the equation color red green x 256 blue x 65536 where red green and blue are the color components ranging from 0 to 255 FILL is the color used to fill the space between the current contour and the next contour level LVISIBLE the contour is visible if LVISIBLE is TRUE LSIZE is the appearance height of the label text in the same unit as the model LDIS is the the distance between two contour labels in the same unit as the model Grid
347. orly permeable bed within a relatively permeable aquifer Fig 3 19 The interbeds are assumed to consist primarily of highly compressible clay and silt beds from which water flows vertically to adjacent coarse grained beds Jo eat o tts i POE 224 5 20 090 94 992 gt 4 97 s ss REE 4 s itt eats Fe LC ee 61 Pao ee se REPE eet totes ogee DET DELL 2 a 4 A Teles Ete ir rette tn re at rut dr LE je Fe s 5 Bee aS erat a4 Pt LLL o Ll oe wate et Me Siege fe cats SOLITI elas t t Pe t ee D L rat otoan e See reat oe ee CARO Hy 0 5 o ott se s Fig 3 19 Types of fine grained beds in or adjacent to aquifers Beds may be discontinuous interbeds or continuous confining beds Adopted from Leake and Prudic 1991 To incorporate the calculation of interbed storage of a layer check the Interbed Storage flag in the Layer Options dialog box see section 3 4 The required data are specified by using the Interbed Storage Package dialog box of the Data Editor Preconsolidation Head or preconsolidation stress H L Preconsolidation head is the previous minimum head value in the aquifer For any model cells in which the specified preconsolidation head is greater th
348. ormat for the labels The Fixed option displays numbers at least one digit to the left and digits to the right of the decimal separator where N is the value specified in Decimal digits 3 9 The Options Menu Processing Modflow 169 The Exponential option displays numbers in scientific format and E is inserted between the number and its exponent Decimal digits determines the number of digits to the right of the decimal separator For example if Decimal digits 2 the value 1241 2 will be displayed as 1241 20 for the fixed option or 1 24E 03 for the exponential option Prefix isa text string that appears before each label Suffix is a text string that appears after each label Restore Defaults Clicking on this button PMWIN sets the number of contour lines to 11 and uses the maxmum and minimum values found in the current layer as the minimum and maximum contour levels The label height and spacing will also be set to their default values Load and Save The contents of the contour level table can be loaded from or saved in separate Contour files Refer to Appendix 2 for the format Environment Options EG Appearance Coordinate System Contours Iv Visible Iv Display contour lines Iv Fill contours Iv Orientlabels uphill Iv Ignore inactive cells Parameter Starting Hydraulic Heads 8 485281 84 85281 LabelHeight Label Spacing cee a 8 485281 84 85281 8 485281 84 85281 8 485281 84 85281 8 485281 84
349. ources or sinks The concentration of a particular source or sink is specified by the Data Editor Point sources include wells general head boundary cells fixed head cells rivers and streams Recharge is the only areally distributed source whereas evapotranspiration is the only sink whose concentration can be specified Note that MT3D does not allow the concurrent use of the rivers and the streams This does not cause problems in any case because the Streamflow Routing package has all functions of the River package The concentration of a sink cannot be greater than that of the aquifer at the sink cell If the sink concentration is specified greater than that of the aquifer it is automatically set equal to the concentration of the aquifer Menu items of this menu are dimmed if the corresponding hydraulic features given in the Models Modflow menu are not used checked You may or may not specify the concentration for the sources or sinks when they are used in the flow simulation The specified concentration will be used in the transport simulation if a corresponding menu item 1s checked If a checked item is no longer necessary for a transport simulation simply select the item again and deactivate it If the concentration of a source or sink is not specified the default value for the concentration 1s Zero Using Time Variant Specified Concentration you may define constant concentration cells anywhere in the model grid and different concentration
350. ow 4 and layer 12 6 6 3 Benchmark Problems and Application Examples from Literatures 302 Processing Modflow 6 7 Miscellaneous Topics 6 7 1 Using the Field Interpolator Folder 5 1 Overview of the Problem This example illustrates the use of the Field Interpolator Fig 6 63 shows the plan view of the model area the model grid and the locations of measurement points The model grid consists of 70 rows 60 columns and one layer The measured hydraulic heads and the coordinates of the measurement points are saved in the file om5 examples misc misc1 measure dat To obtain the starting head distribution of a flow simulation the measured hydraulic heads should be interpolated to each model cell Modeling Approach and Simulation Results The starting heads are interpolated to model cells using the four interpolation methods provided by the Field Interpolator The interpolation results are shown in the form of contours in Fig 6 64 6 67 The octant search method with Data Per Sector 1 is used by all gridding methods A weighting exponent of F 2 is used by Shepard s inverse distance method The Kriging method uses the linear variogram model with cy 0 and a 1 There is no significant difference observed in these figures when sufficient data points are available The major difference 15 observed in the southern part of the model area where only one measurement point 1s found and the system is not we
351. parameter Typically log transformed parameters are those for which negative values are not reasonable for example hydraulic conductivity List of Calibration Parameters UCODE Parameters Prior Information Control Data Options Description Startvalue Minimum Transmissivity in layer 3 T 0 003 10 ce ce ce ce ce ri oo Fig 3 55 The List of Calibration Parameters dialog box 3 6 6 Inverse Modeling 156 Processing Modflow Prior Information Similar to PEST prior information can be defined in the UCODE modeling environment To define a prior information first check the Active flag in the Prior Information tab then enter the prior information equation in the Prior Information column The syntax of a prior information line 1s P EQUATION stat STAT flag STAT FLAG plot PLOT SYMBOL 3 58 where EUQATION is defined by eq 3 59 PVALUE C1 x P1 amp C2xP2 3 59 The components of eq 3 58 and 3 59 need to be separater by one space The components are defined as follows P is the code indicating that a prior information line follows PVALUE The prior information value Specify the decimal value even for a log transformed parameter C1 C2 Coefficients with values as specified by the user X Indicates multiplication Needs to be preceded and f
352. percent of the horizontal hydraulic conductivity The effective porosity 1s 25 percent The elevation of the ground surface top of the first stratigraphic unit is 10m The thickness of the first and the second units is 4 m and 6 m respectively A constant recharge rate of 8x10 m s is applied to the aquifer A contaminated area lies 1n the first unit next to the west boundary The task 1s to 1solate the contaminated area using a fully penetrating pumping well located next to the eastern boundary A numerical model has to be developed for this site to calculate the required pumping rate of the well The pumping rate must be high enough so that the contaminated area lies within the Your First Groundwater Model with PMWIN 8 Processing Modflow capture zone of the pumping well We will use PMWIN to construct the numerical model and use PMPATH to compute the capture zone of the pumping well Based on the calculated groundwater flow field we will use MT3D and MOC3D to simulate the contaminant transport We will show how to use PEST and UCODE to calibrate the flow model and finally we will create an animation sequence displaying the development of the contaminant plume To demonstrate the use of the transport models we assume that the pollutant 1s dissolved into groundwater at a rate of 1x10 ug s m The longitudinal and transverse dispersivities of the aquifer are 10m and 1m respectively The retardation factor is 2 The initial concentration m
353. persion coefficient D porosity n thickness b and an appropriate grid dimension factor For example the dispersion equation coefficient for the j 1 2 1 face in the column direction is n b D i x Ax The output from MOC3D is controlled by using the Output Control MOC3D dialog box Fig 3 38 Most items in this dialog box are self explanatory The names of the separate ASCII or binary output files are given in Table 3 6 M Save data a separate ASCII file Save data a separate binary file C These data will be printed ar saved Jat the end of every stress period These data will be printed or saved every Nth particle M 20 Cancel Help Fig 3 38 The Output Control MOC3D dialog box 3 6 2 MOC3D 118 Processing Modflow Table 3 6 Names of the MOC3D output files Output Term Filename Listing file pathimoc3d Ist Concentration file ASCII path mocconc asc Concentration file binary path mocconc bin Velocity ASCII path mocvel asc Velocity binary path mocvel bin particle location ASCII path mocprt asc particle location binary path mocprt bin path is the folder in which the model is saved MOC3D Run The available settings of the Run Moc3d dialog box Fig 3 39 are described below gt Moc3d Program gives the full path and filename of the executable code of MOC3D PMWIN automatically installs a version of MOC3D in pmhome moc3d moc3d exe where pmhome
354. ping rate of 0 0012 m s v To specify the pumping well and the pumping rate Choose MODFLOW Well from the Models menu Move the grid cursor to the cell 25 15 1 Press the right mouse button and type 1E 10 then click OK Note that a negative value is pole x used to indicate a pumping well Move to the second layer by pressing PgDn Press the right mouse button and type 1E 10 then click OK Move to the third layer by pressing PgDn Press the right mouse button and type 0 0012 then click OK pe 2 oY xs Choose Leave Editor from the File menu or click the leave editor button ge Step 3 Perform the Flow Simulation gt perform the flow simulation 1 Choose MODFLOW Run from the Models menu The Run Modflow dialog box appears Fig 2 7 2 Click OK to start the flow computation Prior to running MODFLOW PMWIN will use the user specified data to generate input files tor MODFLOW and optionally MODPATH as listed in the table of the Run Modflow dialog box An input file will be generated only if the generate flag is set to BI You can click on the button to toggle the generate flag between and Generally you do not need to change the flags as PMWIN will care about the settings Step 4 Check Simulation Results During a flow simulation MODFLOW writes a detailed run record to the listing file pathNOUTPUT DAT where path 1s the folder in which your model data are saved If a flow simulation is successfully
355. placing particles A value around 10 is generally adequate If DCEPT is greater than the relative cell concentration gradient DCCELL eq 3 37 the higher number of particles is placed in the cell j 1 k otherwise the lower number of particles NPL 1s placed see NPH and NPL below T EE CMIN jk DCCELL 3 37 ae CMAX CMIN d where CMIN x and CMAX are the minimim and maximum concentrations in the immediate vicinity of the cell j 1 k CMIN and CMAX are the minimum and maximum concentration in the entire grid respectively gt NPLANE is flag indicating whether the random or fixed pattern is selected for initial placement of moving particles NPLANE 0 the random pattern is selected for initial placement Particles are distributed randomly in both the horizontal and vertical directions Fig 3 41b This option generally leads to smaller mass balance discrepancy in nonuniform or diverging converging flow fields NPLANE gt 0 the fixed pattern is selected for initial placement The value of NPLANE serves as the number of vertical planes on which initial particles are placed within each cell block Fig 3 41a This fixed pattern may work better than the random pattern only in relatively uniform flow Fields For two dimensional simulations in plan view set NPLANE 1 For cross sectional or three dimensional simulations NPLANE 2 is normally adequate Increase NPLANE if more resolution in th
356. played and used for calculating the variance between observed and calculated values only when the corresponding Plot flag in the Borehole table is checked You can edit the text on the scatter diagram by clicking the mouse on the desired text Clicking on the Save Plot As you can save the plot in the Windows BMP format The other options are self explanatory 5 6 The Graph Viewer Processing Modflow B value Tables 3 X 069 315 3459 547 0555 848 2805 1238 872 1248 94 2410 729 3271 054 4389 47 l l d M ee M e I 5 ao 5 o 5843 427 7733 562 Observed Heads Variance 7 958715 137 1069 315 3459 1 747802E 02 0479154 547 0566 848 2805 8 528499E 02 1256247 1239 872 557553 1748 34 e077021 2410 729 3271 054 4389 477 2480541 2077426 326811 5843 427 7733 562 3653525 4034833 Fig 5 11 The Scatter Diagramm dialog box 213 5 6 The Graph Viewer 214 Processing Modflow FOR YOUR NOTES 5 6 The Graph Viewer Processing Modflow 215 6 Examples and Applications The sample problems contained in this chapter are intended to illustrate the use of PMWIN and the supported programs The sample problems are described in the following sections Each section deals with a specific theme The models of each section can optionally be installed duri
357. put Files 198 Processing Modflow FOR YOUR NOTES 4 4 PMPATH Output Files Processing Modflow 199 5 Modeling Tools 5 1 The Digitizer To activate the digitizer choose Digitizer from the Tools Menu The Digitizer is based on the Data Editor Using the Digitizer you can digitize shift or delete points and assign a value to each of these points An additional menu item Points in the Value menu allows you to delete all digitized points or save or load the points in or from an XYZ file An XYZ file can be accepted by the Field Interpolator and has the following format N first line of the file N is the number of digitized points The maximum allowed number is 10 000 Y 2 second line of the file X Y gt 2 third line of the file X Y Z i 1 th line of the file Xu Yu Z last line of the file gt digitize a point 1 Click the Digitize button You don t need to click the icon if its relief is already sunken 2 Click the mouse cursor on the desired position to set a point gt shift a digitized point Click the Digitize button 2 Point the mouse cursor to a digitized point holding down the left mouse button while moving the mouse 3 Release the mouse button when the point is moved to the desired position gt To delete a digitized point Click the Digitize button 2 Hold down the Ctrl key and click the mouse cursor on a point 5 1 The Digitizer 200 Processing Modflow gt assign
358. r A GHB cell is equivalent to a constant head cell if a very large C is used The values C and h are constant during a given stress period For transient flow simulations involving several stress periods these values can be different from period to period This allows you to change the head at constant head boundaries as the transient simulation progresses 3 6 1 MODFLOW 84 Processing Modflow MODFLOW Horizontal Flow Barrier The Horizontal Flow Barrier package simulates thin low permeability geologic features such as vertical faults or slurry walls that impede the horizontal flow of groundwater These geologic features are approximated as a series of horizontal flow barriers conceptually situated on the boundaries between pairs of adjacent cells in the finite difference grid Refer to Hsieh and Freckleton 1993 for the numerical implementation of the Horizontal Flow Barrier package A horizontal flow barrier is defined by assigning the following values to a model cell in the Horizontal Flow Barrier Package dialog box Fig 3 18 Barrier Direction and Hydraulic Conductivity Thickness of the barrier TDW for unconfined layers or Transmissivity Thickness of the barrier TDW LT for confined layers Horizontal Flow Barrier Package EI Barrier Direction 1 4 3 Hydraulic conductivity Thickness of the Baririer 1 T e 8 Directions 3 14 2 4 0 No Barrier Cancel Help Fig 3 18 The Ho
359. r a given discretization than linear interpolation And in the presence of strong heterogeneities between adjacent cells within a layer it would usually be preferable to select the linear interpolation scheme gt Maximum number of particles NPMAX Maximum number of particles available for particle tracking of advective transport in MOC3D If set to zero the model will calculate 3 6 2 MOC3D Processing Modflow 113 NPMAX according to eq 3 31 NPMAX 2 NPTPND NSROW NSCOL NSLAY 3 31 where NPTPND is the initial number of particles per cell see below The values NSROW NSCOL and NSLAY are the number of rows columns and layers of the transport subgrid respectively gt Courant number CELDIS is the number of cells or the fraction of a cell that a particle may move through in one step typically 0 5 lt CELDIS lt 1 0 gt Fraction limit for regenerating initial particles FZERO If the fraction of active cells having no particles exceeds FZERO the program will automatically regenerate an initial particle distribution before continuing the simulation typically 0 01 FZERO lt 0 05 gt Initial number of particles per cell NPTPND Valid options for default geometry of particle placement include 1 2 3 or 4 for one dimensional transport simulation 1 4 9 or 16 for two dimensional transport simulation and 1 8 or 27 for three dimensional transport simulation The user can also customize initial place
360. r click the right mouse button on the edit field and select a file from a Plot File dialog box Note that cross sectional plots can only be included in the DXF and BMP format PMPATH uses the same color resolution as the video screen to capture and save Windows Bitmap files The option Use Polyline to save contours should only be used if your graphics software accept the DXF entity POLYLINE B Save Plot As Format File c pmwin sexamplesspmex pmb 1 exeample cht Iv Include the lower cross section Iv Include the right cross section Use polyline to save contours po right mouse button an the file fields to select a file za Fig 4 13 The Save Plot As dialog box If the MODPATH format is chosen coordinates along the path of each particle are recorded in the file specified in the Save Plot As dialog box The file contains the starting coordinates of a particle and the coordinates at every point where a particle enters a new cell In addition coordinates of intermediate points are saved whenever a particle tracking step length is reached The pathline file contains a sequence of one line records each line containing coordinate and location information for one point on a pathline Each record contains nine variables and is written using the FORTRAN format 15 1X 5 E20 12 1X 2 13 1X 13 4 4 PMPATH Output Files 196 Processing Modflow The variables in the order of appearance on the line are defined as Particle i
361. r minus leakage from or to the aquifer in the upstream reach The accounting scheme used in this package assumes that streamflow entering the modelled reach is instantly available to downstream reaches This assumption is generally reasonable because of the relatively slow rates of groundwater flow Streamflow into a segment that 1s formed from tributary streams 1s computed by adding the outflows from the last reach in each of the specified tributary segments If a segment is a diversion then the specified flow into the first reach of the segment is subtracted from flow in the main stream However if the specified flow of the diversion is greater than the flow out of the segment from which flow 15 to be diverted then no flow is diverted from that segment In the Data Editor you can press the right mouse button and specify the following required cell values in the Streamflow Routine Package dialog box Fig 3 23 The specified cell values will be shown from left to right on the status bar gt Segment 15 a number assigned to a group of reaches Segments must be numbered in downstream order The maximum number allowed in PMWIN 15 25 3 6 MODFLOW Processing Modflow 93 Reach is a sequential number in a segment that begins with one for the farthest upstream reach and continues in downstream order to the last reach in the segment In PMWIN you can only assign one reach to a model cell although the Streamflow Routing package allows
362. rameters fall neatly into separate groups which can be treated similarly in terms of calculating derivatives Number is the group number The maximum number of parameter groups is 150 Description A text describing the estimated parameter can be entered here optional for example Transmissivity Group 1 A maximum of 120 characters is allowed INCTYPand DERINC INCTYP defines the type of parameter increment perturbation used for forward difference calculation of derivatives with respect to any parameter belonging to the group INCTYP can be Relative Absolute or Rel to max If it is Relative the increment is calculated as a fraction of the current value of that parameter that fraction is specified in DERINC If INCTYP is Absolute the parameter increment is fixed at the value of DERINC and if INCTYP is Rel to max the parameter increment is calculated as a fraction of the group member with highest absolute value that fraction 3 6 5 PEST Inverse Modeling Processing Modflow 145 again being DERINC If a group contains members which are fixed and or tied you should note that the values of these parameters are taken into account when calculating parameter increments using the Rel to max option For the Relative and Rel to max options a DERINC value of 0 01 1s often appropriate However no suggestion for an appropriate DERINC value can be provided for the Absolute increment option the most appropriate increment will depend on
363. ransport models each flow time step 1s further divided into smaller transport steps The length of stress periods is not relevant to a steady state flow simulation However as we want to perform contaminant transport simulation with MT3D and MOC3D the actual time length must be specified in the table Enter 9 46728E 07 seconds for Length of the first period Click OK to accept the other default values Now you need to specify the initial hydraulic head for each model cell The initial hydraulic head at a fixed head boundary will be kept constant during the flow simulation The other heads are starting values in a transient simulation or first guesses for the iterative solver in a steady state simulation Here we firstly set all values to 8 and then correct the values on the west side by overwriting them with a value of 9 To specify the initial hydraulic head 2 Run a Steady State Flow Simulation Processing Modflow 15 l Choose Initial Hydraulic Heads from the Parameters menu PMWIN displays the model grid Choose Reset Matrix from the Value menu or press Ctrl R and enter 8 in the dialog box then click OK Move the grid cursor to the upper left model cell Press the right mouse button and enter 9 into the Cell Value dialog box then click OK Now turn on duplication by clicking the duplication button Ea Duplication is on if the relief of the duplication button is sunk The current cell value will be duplic
364. ration from the Models menu For the current example we accept the default value O for all cells Note that PMWIN automatically uses the same initial concentration values for both MOC3D and MT3D 2 Choose Leave Editor from the File menu or click the leave editor button e gt define the transport subgrid and the concentration outside of the subgrid 1 Choose MOC3D Subgrid from the Models menu The Subgrid for Transport MOC3D dialog box appears Fig 2 29 The options in the dialog box are grouped under two tabs Subgrid and C Outside of Subgrid The default size of the subgrid is the same as the model grid used to simulate flow The default initial concentration outside of the subgrid is zero We will accept the defaults 2 Click OK to accept the default values and close the dialog box Subgrid for Transport MOC3D LX Subgrid C Outside of Subgrid Number of first layer for transport Number of last layer for transport Number of first row for transport iu Number of last row for transport 0 Number of first column for transport Number of last column for transport 0 Cancel Help Fig 2 29 The Subgrid for Transport MOC3D dialog box 2 2 2 Perform Transport Simulation with MOC3D 40 Processing Modflow To assign the input rate of contaminants Choose MOC3D Sink Source Concentration Recharge from the Models menu Assign 12500 ug m to the cells within the contamin
365. ream not included in model simulation Fig 6 31 Numbering system of streams and diversions after Prudic 1988 6 2 7 Simulation of a Flood in a River 266 Processing Modflow 6 2 8 Simulation of Lakes Folder pm5 examples basic Woasic8 Overview of the Problem Fig 6 32 shows an unconfined aquifer with the boundary conditions and the location of a planned open cast mining site The aquifer 1s bounded by a no flow zone to the north and to the south To the west and east exist fixed head boundaries with the hydraulic heads h 100 m and 95 m the elevations of the aquifer top and bottom 100 and 0 m respectively The aquifer is homogeneous and isotropic with a measured horizontal hydraulic conductivity of 0 0001 m s and vertical hydraulic conductivity of 0 00001 m s The specific yield and effective porosity are assumed to be 0 25 The specific storage coefficient S 0 0001 In the final mining phase the hydraulic head within the mining site must be drawn down to the level of h 21 m Afterwards the mining site will be filled with water to form an artificial lake Your task 1s to 1 construct a steady state flow model and calculate the necessary abstraction rate inflow into the mining site for holding the head at 21 m and 2 use the calculated steady state head as the initial hydraulic head and calculate the temporal development curve of the water level head vs time in the artificial lake for the case that the abstractio
366. ren t already in Layer 1 change to it by using the Page Up PgUp key 2 place the particles the ground surface drag a box around the cell 6 5 1 3 Inthe Cell Faces tab of the Add New Particles dialog box you will notice that the figure defines the various faces of an individual cell since the contamination 1s a surface source we only want to place particles on cell face 5 4 Click the Particles tab and set the number of particles on Face 5 to NI 4 and NJ 4 and set NI and NJ on all the other faces to O Click OK to leave the Add New Particles dialog box Open the Particle Tracking Time Properties dialog box by Options Particle Tracking Time 7 In the Tracking Steps group change the time unit to years step length to 1 and maximum number of steps to 75 When finished click OK to leave the dialog box 8 Start the backward particle tracking by Run gt Forward 9 Repeat the above for Maximum number of steps of 100 and 125 The plot generated after 125 steps should look similar to Fig 6 13 ex an Na S u LETENI a cra Le F EI T OX CC RIS At Hie yo mU en NUS THA ft CEST D y D H aca Ave South Granite Hills pe os i3 i os ONE eT ee a CLE A LU lo DP ee ee Fig 6 12 Steady state hydraulic head distribution in the third model layer and capture zones of pumping wells 6 1 2 Tutorial 2 Confined and
367. rface or the hydraulic heads of the highest active cells on the cross sections check the Groundwater surface Potential check box Use Exaggeration scaling factor for the height to change the appearance height of the cross sections A larger exaggeration value lets you see the projection of the pathlines on the cross section windows in greater details The exaggeration value can be ranged from 0 01 to 1000 If the model thickness or the exaggeration value is too small such that the appearance size on the screen is smaller than 1 pixel PMPATH will turn off the display 4 3 PMPATH Options Menu 188 Processing Modflow of the cross sections In this case the Visible check box will be unchecked automatically Projection Row and Projection Column PMPATH uses a grid cursor to define the column and row for which the cross sectional plots should be made You can move the grid cursor by holding down the Ctrl key and click the left mouse button on the desired position Alternatively you can type the row and column in the Projection Row and Projection Column edit boxes The visible part on the cross sectional plots is defined by Minimum Elevation and Maximum Elevation By default the maximum elevation is set to the highest elevation of the model grid or the largest hydraulic head The minimum elevation is set to the lowest elevation of the model grid or the smallest hydraulic head gt Velocity vectors Velocity vectors describe the directions
368. rge c pm5data samplel moccrch dat Options Regenerate all input files Check the model data Generate inputfiles only don t start MOC3D Don t generate MODPATH files anyway Cancel Help Fig 2 33 The Run MOC3D dialog box 2 2 2 Perform Transport Simulation with MOC3D Processing Modflow 43 gt Check simulation results and produce output During a transport simulation MOC3D writes a detailed run record to the file path MMOC3D LST where path is the folder in which your model data are saved MOC3D saves the simulation results in various files which can be controlled by choosing MOC3D Output Control from the Models menu To check the quality of the simulation results mass balance calculations are performed and saved in the run record file The mass in storage at any time is calculated from the concentrations at the nodes of the transport subgrid to provide summarized information on the total mass into or out of the groundwater flow system The mass balance error will typically exhibit an oscillatory behavior over time because of the finite difference approximation and the nature of the method of characteristics As discussed in Konikow et al 1996 as long as the oscillations remain within a steady range not exceeding about 10 percent as a guide then the error probably does not represent a bias and 1s not a serious problem Rather the ocillations only reflect the fact t
369. ries which are associated with different source concentrations Zones are defined within the IBOUND array by specifying unique negative values For example if you have three zones you will use 1 2 and 3 for the fixed head cells Note that 3 4 The Grid Menu Processing Modflow 73 the associated concentrations can be specified by selecting MOC3D Sink Source Concentration gt Fixed Head Cells from the Models menu gt ICBUND MT3D An ICBUND array is required by the transport models MT3D and MT3DMS ICBUND contains a code for each model cell A positive value in the ICBUND array defines an active concentration cell the concentration varies with time and is calculated a negative value defines a constant concentration cell the concentration 15 constant and the value 0 defines an inactive concentration cell no transport simulation takes place at such cells It is suggested to use the value 1 for an active concentration cell 1 for a constant concentration cell and 0 for an inactive concentration cell Note that the ICBUND array applies to all species if MT3DMS is used MT3D and MT3DMS automatically convert no flow or dry cells to inactive concentration cells Active variable head cells can be treated as inactive concentration cells to minimize the area needed for transport simulation as long as the solute transport is insignificant near those cells For constant concentration cells the initial concentration remains the same
370. rizontal Flow Barrier Package dialog box Current Position Column Row 17 15 The barrier direction indicates the cell face where the barrier 1s located To erase an existing barrier use zero for the barrier direction The second value TDW gives the hydraulic characteristic of the barrier If a layer is unconfined type 1 or 3 TDW is the barrier hydraulic conductivity divided by the thickness of the barrier If a layer is confined type 0 or 2 TDW is the barrier transmissivity divided by the thickness of the barrier The barrier thickness 1s included implicitly in TDW MODFLOW Interbed Storage For steady state flow simulations this menu item is not used and is therefore dimmed Groundwater 1s released from storage under conditions of decreasing hydraulic head The released water volume is proportional to the compressibility of the soil matrix and water because a 3 6 1 MODFLOW Processing Modflow 85 reduction of the hydraulic head results in an increase in the effective stress on the soil skeleton and a decrease of the water pressure Increasing effective stress on the soil skeleton results to deformation compaction of the soil matrix The Interbed Storage package Leake and Prudic 1991 calculates the water volume released from storage and simulates elastic and inelastic compaction of compressible fine grained beds in an aquifer due to groundwater extraction The term interbed is used to denote a po
371. rmat of the input files You can find the documentions the folder document of the companion CD ROM Name File MODFLOW 88 MODFLOW 96 and MOCSD require a so called Name File The name file is also required if you want to import an existing model into PMWIN The name file contains a list of file types unit numbers and the associated file name File Format 1 Data FTYPE NUNIT FNAME Explanation of Fields Used in Input Instructions ALL DATA IN THE SAME RECORD ARE SEPARATED BY A COMMA OR BLANK FTYPE lis the file type which must be one of the following character values FTYPE may be entered in uppercase or lowercase LIST for the simulation listing file BAS for the Basic Package OC forthe Output Control Option BCF for the Block Centered Flow Package RCH for the Recharge Package RIV for the River Package WEL for the Well Package DRN for the Drain Package GHB for the General Head Boundary Package EVT forthe Evapotranspiration Package SIP for the Strongly Implicit Procedure Package SOR for the Slice Successive Over Relaxation Package DATA BINARY for binary unformatted files such as those used to save cell by cell budget data and binary unformatted head and drawdown data DATA for formatted text files such as those used to save formatted head and drawdown and for input of array data from files that are separate from the primary package input files NUNIT is the Fortran unit to be used when reading from or writing to the file Any lega
372. roperties K L W M v N 2m day 250 125 m depending on the length of the river within the cell 100m Im To specify the river data Select Models gt MODFLOW River You will notice that the river meanders across the model domain and rarely is contained within a single cell First you need to decide the river data for each cell using the equation above The river data 15 entered by selecting the appropriate cell with the left mouse button and then clicking with the right mouse button to enter the river data associated with that cell Entering the river data is sometimes very cumbersome Fortunately we have saved the river hydraulic conductance head and elevation of the riverbed bottom 1n three ASCII matrix files so we need only to import them To import river data select Value Matrix In the Browse Matrix dialog box select River Hydraulic Conductance from the Parameter drop down box then click Load to import the conductance file pm5 examples tutorials tutorial2 t2riverc dat Select Head in the River from the Parameter drop down box then click Load to import the head file pm5 examples tutorials tutorial2 t2riverh dat Finally select Elevation of the Riverbed Bottom then click Load to import the file pm5 examples tutorials tutorial2 t2riverb dat You should see the cells specified as river cells highlighted in light blue Leave the Data Editor by File Leave Editor Yes Wells v pe
373. rsion factor C depends on the length and time units of your model 1 3 1 3 1 3 1 3 C 1 7 4486 I 128383 T 86400 2 S S 3 22 Stream Structure describes the configuration of the stream system Each row in the table Fig 3 23 represents a stream segment in the model Each segment can have up to 10 tributary segments The numbers of the tributary segments are specified in the columns 1 to 10 The column Iupseg is the number of the upstream segment from which water is diverted For a segment that is not a diversion Iupseg must be specified as zero Iupseg is used only when the option Simulate diversions from segments is checked The values in Fig 3 24 indicate that segment 2 is diverted from segment 1 segment is a tributary segment of segment 3 and segments 2 and 4 are tributary segments of segment 5 The configuration of the stream system is shown in Fig 3 25 3 6 1 MODFLOW 94 Processing Modflow gt Parameter Number is used to assign the streambed hydraulic conductance Corp as a parameter for an automatic calibration by the inverse models PEST or UCODE see PEST gt Parameter List or Parameter List Similar to the River package leakage Q to or from the aquifer through the streambed is computed by A gt 5 3 23 Csrg Hs Sgor lt 5 where H is the head in the stream h is the head in the model cell beneath the streambed and Sgot is th
374. ry about these flags as PMWIN will take care of the settings Note that you cannot run MODPATH Pollock 1989 and or MODPATH PLOT Pollock 1994 from PMWIN directly See Appendix 6 for how to run these programs gt Options Regenerate all input files for MODFLOW You should check this option if the input files have been deleted or overwritten by other programs Check the model data Before creating data files for MODFLOW PMWIN will check the geometry of the model and the consistency of the model data as given in table 3 5 if this option is checked The errors if any are saved in the file CHECK LST located in the same folder as your model data Generate input files only don t start MODFLOW Check this option if you do not want to run MODFLOW You can start the simulation at a later time by executing the batch file MODFLOW BAT gt Click OK to start the generation of MODFLOW input files In addition PM WIN generates a batch file MODFLOW BAT saved in your model folder When all necessary files are generated PMWIN automatically runs MODFLOW BAT in a DOS window During a flow simulation MODFLOW writes a detailed run record to the file OUTPUT DAT saved in your model folder MODFLOW saves the simulation results in various unformatted binary files only if a flow simulation has been successfully completed See MODFLOW Output Control for details about the output terms from MODFLOW Run Modflow x Modflow Version
375. s Fig 2 14 To save or print the graphics choose Save Plot As or Print Plot from the File menu Press PeDn to move to the second layer Repeat steps 2 to 9 to load the file H2 DAT display and save the plot Choose Leave Editor from the File menu or click the leave editor button ge and click Yes 2 Run a Steady State Flow Simulation Processing Modflow 25 to save changes to Presentation Using the procedure described above you can generate contour maps based of your input data any kind of simulation results or any data saved as an ASCII Matrix file For example you can create a contour map of the starting heads or you can use the Result Extractor to read the concentration distribution and display the contours You can also generate contour maps of the fields created by the Field Interpolator or Field Generator See chapter 5 for details about the Field Interpolator and Field Generator 4 Results Extractor MODFLOW MT3D 5 Result Stress Period fi Time Step fi Orientation E View Layer fi ColumnWidth i 4 a Mar 4 4 Browse Matrix Paramter Column Width Presentation 14 w Oo On rho coco co co Cc co co co co co CoO CoO coco co co co cco cco coco CoO CoO cjojojojojojojojojojojojojojojo coco coco co co co co co co co co CoO
376. s assumed to have the same concentration as the fluid in the aquifer However if the fluid sink 1s associated with evaporation or transpiration itis assumed that the fluid discharge mechanism will exclude dissolved chemicals which results in an increase 1n concentration at the location of the sink Items of this menu are dimmed if the corresponding hydraulic features given in the Models gt Modflow menu are not used checked The specified concentration will be used by MOC3D if a corresponding menu item is checked If a checked item is no longer necessary for a transport simulation simply select the item again and deactivate it 3 6 2 MOC3D Processing Modflow 117 i Source Concentration Fixed Head of x Zones are defined within the BOUND array by specifying unique negative values tor fixed head cells ta be associated with seperate fluid source concentration Max 200 zones are allowed here Source Concentration 3 gt E 100 250 150 0 Ld 0 0 OK Cancel Help Fig 3 37 The Source Concentration Fixed Head dialog box MOC3D gt Output Control The main output file of MOC3D 1s the listing file MOC3D LST MOC3D includes output options to create separate ASCII or binary files for concentration velocity and the location of particles Optionally the dispersion equation coefficients on cell faces can be written to the listing file The dispersion equation coefficient is a combination of dis
377. s at a distance of 55 m from the pumping well The match of these two curves is very good While the use of the analytical solution is limited to the primary assumptions the numerical model can be used to evaluate pumping tests even if the confining aquitard Fig 6 41 has a higher value of the vertical hydraulic conductivity and the hydraulic head in the overlying aquifer is not constant during the pumping To do this simply specify all model cells as active cells This is allowed because the simulation time is normally very short and the extent of the model domain is relative large so that at end of a transient flow simulation the drawdown values at the model boundaries are acceptable low If the vertical hydraulic conductivity of the aquitard is known we can use PEST or UCODE 6 4 4 Transient Flow to a Well in a Leaky Confined Aquifer Processing Modflow 281 to estimate the horizontal hydraulic conductivity and storage coefficient of the leaky aquifer by defining them as estimated parameters Click Models PEST Run or Models UCODE gt Run to see how the inverse models work Because the analytical drawdown values were used as the observations the results from the inverse models must be horizontal hydraulic conductivity 2 3 x 10 m s and storage coefficient 0 00075 If the vertical hydraulic conductivity is unknown and needs to be estimated we will need additional drawdown values in the overlying aquifer during the pumpin
378. s fixed head boundary with the hydraulic head h 40 m The compaction and thus the land surface subsidence of the confining bed 1s modelled by the Interbed Storage package A transient flow simulation with one stress period and 30 time steps has been carried out The length of the stress period is one year 3 1536 x 10 seconds The required withdrawal rate changes with time and can be calculated by using the water budget calculator by assigning the zone number 1 to the pit For the first time step the required withdrawal rate is 6 5 5 Compaction and Subsidence Processing Modflow 203 0 0134 m s 48 2 m h For the last time step it is reduced to 0 0066 m s 23 76 m h The distribution of the subsidence caused by this withdrawal rate can be obtained by using the Results Extractor Fig 6 57 shows the isolines of the land surface subsidence for the last time step The maximum subsidence 1s about 0 11 m You can find two additional examples described in Leake and Prudic 1991 in the folders geotechniques geoda and geotechniques geo5db DL L1 Lll Sl TN X inks groundwater sur NN T one 25 m cell width 400 m 50 400 m Fig 6 56 Model grid and boundary conditions 6 5 5 Compaction and Subsidence 204 Processing Modflow Fig 6 57 Distribution of the land surface subsidence maximum 0 11 m 6 5 5 Compaction and Subsidence Processin
379. s for sink cells NLSINK No of particles used to approximate sink cells NPSINK Critical relative concentration gradient DCHMOC OK Cancel Help Fig 3 49 The Advection Package MT3DMS dialog box gt Solution Scheme MT3DMS provides five solution schemes for the advection term including the method of characteristics MOC modified method of characteristics MMOC hybrid method of characteristics HMOC upstream finite difference method and third order TVD method ULTIMATE The first three methods are the same as in MT3D The finite difference method can be explicit as in MT3D or fully implicit without any stability constraint to limit transport step sizes The finite difference solution is implicit when the Generalized Conjugate Gradient solver GCG package is activated see MT3DMS gt Solver gt GCG The third order TVD method is based on the ULTIMATE algorithm Leonard 1988 Leonard and Niknafs 1990 1991 which is in turn derived from the earlier QUICKEST algorithm Leonard 1979 With the ULTIMATE scheme the solution is mass conservative without excessive numerical dispersion and artificial oscillation 3 6 4 MT3DMS 134 Processing Modflow gt Weighting Scheme is needed only when the implicit finite difference method is used 1 the solution scheme is finite difference and the iterative GCG solver 1s used In the finite difference method when computing the mass flux into a model c
380. schemes The major drawback of the MOC scheme is that it can be slow and requires a large amount of computer memory when a large number of particles is required The modified method of characteristics MMOC uses one particle for each finite difference cell and is normally faster than the MOC technique At each new time level a particle is placed at the nodal point of each finite difference cell The particle is tracked backward to find its position at the old time level The concentration associated with that position is used to approximate the advection relevant average concentration at the cell where the particle is placed The MMOC technique is free of artificial oscillations if implemented with a lower order velocity interpolation scheme such as linear interpolation used in MT3D and MT3DMS However with a lower order velocity interpolation scheme the MMOC technique introduces some numerical dispersion especially for sharp front problems The hybrid method of characteristics HMOC attempts to combine the strengths of the MOC and MMOC schemes by using an automatic adaptive scheme conceptually similar to the one proposed by Neuman 1984 The fundamental idea behind the scheme 15 automatic adaptation of the solution process to the nature of the concentration field When sharp 3 6 3 MT3D Processing Modflow 121 concentration fronts are present the advection term is solved by MOC through the use of moving particles dynamically distributed
381. se Boundary Condition gt IBOUND Modflow from the Grid Menu The Data Editor of PMWIN appears with a plan view of the model grid Fig 2 6 The grid cursor is located at the cell 1 1 1 that is the upper left cell of the first layer The value of the current cell 15 shown at the bottom of the status bar The default value of the IBOUND array 15 1 The grid cursor can be moved horizontally by using the arrow keys or by clicking the mouse on the desired position To move to an other layer use PgUp or PgDn keys or click the edit field in the tool bar type the new layer number and then press enter Note that a DXF map is loaded by using the Maps Options See Chapter 3 for details 2 Press the right mouse button PMWIN shows a Cell Value dialog box 1 in the dialog box then click OK The upper left cell of the model has been specified to be a fixed head cell 4 Now turn on duplication by clicking the duplication button Ea Duplication is on 1f the relief of the duplication button is sunk The current cell value will be duplicated to all cells passed by the grid cursor if it is moved while duplication is on You can turn off duplication by clicking the duplication button again 5 Move the grid cursor from the upper left cell 1 1 1 to the lower left cell 1 30 1 of the model grid 2 Run a Steady State Flow Simulation Processing Modflow 13 The value of 1 1s duplicated to all cells on the west side of the mod
382. ser specified model data b is a vector of defined flows terms associated with head dependent boundary conditions and storage terms at each cell Xis a vector of hydraulic heads at each cell One value of the hydraulic head for each cell is computed at the end of each time step At present PMWIN supports four packages solvers for solving systems of simultaneous linear equations the Direct Solution DE45 package the Preconditioned Conjugate Gradient 2 PCG2 package the Strongly Implicit Procedure SIP package and the Slice Successive Overrelaxation SSOR package Input parameters of these solution methods are discussed below See McDonald and Harbaugh 1988 Hill 1990a and Harbaugh 1995 for detailed mathematical background and numerical implementation of these solvers Various comparisons between the solution methods can be found in Trescott 1977 Behie and Forsyth 1983 Scandrett 1989 and Hill 1990b Hill indicates that the greatest differences in solver efficiency on scalar computers occur for three dimensional non linear problems For these types of problems it may be well worth the time and effort to try more than one solver If your model does not have a large number of active cells you may try to use the direct solver DE45 Otherwise SIP generally is a good alternative to consider Note that the MODFLOW version MODFLOW Density package from KIWA does not support the Direction Solution package 3 6
383. servation boreholes Calibration of a flow model is accomplished by finding a set of parameters hydrologic stresses or boundary conditions so that the simulated heads or drawdowns match the measurement values to a reasonable degree The calibration process is one of the most difficult and critical steps in the model application Hill 1998 gives methods and guidelines for model calibration using inverse modeling To demonstrate the use of the inverse models PEST and UCODE within PMWIN we assume that the hydraulic conductivity in the third layer is homogeneous but its value 15 unknown We want to find out this value through a model calibration by using the measured hydraulic heads at the observation boreholes listed below Borehole X coordinate 1 130 2 200 3 480 4 460 2 3 Automatic Calibration Y coordinate 200 400 250 450 Layer Hydraulic Head 8 85 8 74 8 18 8 26 Processing Modflow 45 Three steps are required for an automatic calibration li v E Assign the zonal structure of each parameter Automatic calibration requires a subdivision of the model domain into a small number of reasonable zones of equal parameter values The zonal structure is given by assigning to each zone a parameter number in the Data Editor Specify the coordinates of the observation boreholes and the measured hydraulic heads Specify the starting values upper and lower bounds for each parameter To assign the zo
384. set this area to inactive gt specify the IBOUND data 1 Select Grid gt Boundary Condition IBOUND Modflow 2 Make sure the cell selected is 1 1 1 and click the right mouse button to open the Cell Value dialog box Since this is going to be a fixed head boundary enter 1 and click OK to exit the dialog box The cell should now have a blue color signifying that it has been set as fixed head To save doing this for the remaining fixed head cells it 1s possible to copy the value in this case 1 to any other cell 3 Click on the Duplication Button sunk duplication is activated if the relief of the button is 4 Simply click the left mouse button in any cell that you want to specify as a fixed head cell If you make a mistake turn off the Duplication Button and click the right mouse button in the cell where you have entered the wrong value and replace it with the desired value 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge Processing Modflow 22 5 Complete specifying the entire North boundary as fixed head cells We will assign a head value to these cells a little later The outer grid boundaries are assigned as No Flow by default However the mountain area in the south corner of the domain which is impervious and still falls inside the model grid needs to be explicitly assigned as No Flow ie IBOUND 0 v To specify the no flow zone Ensure Duplication is off and click in a cell within
385. sport simulation gt assign the boundary condition to MT3D 1 Choose Boundary Conditions gt ICBUND MT3D MT3DMS from the Grid menu For the current example we accept the default value 1 for all cells 2 Choose Leave Editor from the File menu or click the leave editor button pel gt set the initial concentration 1 Choose MT3D Initial Concentration from the Models menu For the current example we accept the default value O for all cells 2 Choose Leave Editor from the File menu or click the leave editor button ge gt assign the input rate of contaminants Choose MT3D Sink Source Concentration Recharge from the Models menu 2 Assign 12500 ug m to the cells within the contaminated area This value is the concentration associated with the recharge flux Since the recharge rate is 8 x 10 m m s and the dissolution rate is 1 x 10 ug s m the concentration associated with the recharge flux is 1 x 10 8 x 10 12500 ug m 3 Choose Leave Editor from the File menu or click the leave editor button gel gt assign the transport parameters to the Advection Package 1 Choose MT3D Advection from the Models menu An Advection Package MTADV1 dialog box appears Enter the values as shown in Fig 2 22 into the dialog box select Method of Characteristics MOC for the solution scheme and First order Euler for the particle tracking algorithm 2 2 Perform Transport Simulation with MT
386. steady state simulation 1 Select Tools gt Results Extractor You will see the Results Extractor dialog box which looks a little like a spreadsheet type window In the Results Type box at the top of the dialog box it 1s possible to choose the sort of data you wish to load while the Stress Period Time Step and Layer boxes allow you to select the layer and time of the results loaded If you choose the other tabs MOC3D MT3D MT3DMS you are presented with another choice as to which set of concentration terms you would like to load At the moment however we are only concerned with the hydraulic head distribution Make sure Hydraulic Head is selected in the Results Type box 3 Click the mouse button on Read the hydraulic head values for the steady state solution will appear in the spreadsheet 4 Wewill need to view this data graphically and to use it as the starting heads for the transient simulation so choose Save 5 Inthe Save Matrix As dialog box enter TISS DAT as the filename and click on OK to exit the dialog box 6 Click on Close to exit the Results Extractor dialog box As mentioned above it is possible to save any form of output generated by MODFLOW as a 2D ASCII data file for use in PMWIN or other software The Data Editor is used to load a particular data file as input data for the MODFLOW simulation all that needs to be done is start the Data Editor for the parameter you wish to modify Data files may be created in other so
387. steps will be determined by an automatic stepsize control procedure in MT3D MXSTRN is the maximum number of transport steps TTSMULT is the multiplier for the length of successive transport steps within a flow time step if the Generalized Conjugate Gradient GCG solver is used and the solution option for the advection term is the upstream finite difference method Trace File A Trace file can be saved or loaded by the Search and Modify dialog box see section 3 3 7 File Format 1 Data LABEL The following data repeats 50 times one record for each search range 3 Data ACTIVE COLOR MIN MAX VALUE OPTION Explanation of Fields Used in Input Instructions ALL DATA IN THE SAME RECORD ARE SEPARATED BY A COMMA OR BLANK LABEL is the file label It must be PMWIN4000 TRACEFILE ACTIVE a search range see MIN MAX below is active if ACTIVE 1 COLOR is the fill color The color is defined by a long integer using the equation color red green x 256 blue x 65536 where red green and blue are the color components ranging from 0 to 255 COLOR is assigned to the finite difference cells that have a value located within the search range see MIN MAX below MIN MAX define the lower limit and upper limit of the search range VALUE According to OPTION see below you can easily modify the cell values see section 3 3 7 for details OPTION OPTION 0 Display only OPTION 1 Replace The cell values are replaced by VALUE OPTION
388. stribution from step 3 is subtracted from the distribution from step 2 yielding kriging residuals 5 The kriging residuals are added to the distribution from step 1 yielding a realization which has the same correlation length and passes through the measured values at the measurement points 5 3 The Field Generator 208 Processing Modflow 5 4 The Results Extractor Normally simulation results rom MODFLOW MT3D or MT3DMS are saved unformatted binary and cannot be examined by using usual text editors Using the Results Extractor you may extract specific results from the result files and save them in ASCII Matrix or Surfer Data files see Appendix 2 for the format There are two ways to start the Result Extrator If you are in the main menu of PMWIN select Result Extractor from the Tools menu If you are using the Data Editor select Result Extractor from the Value menu The Result Extractor dialog box Fig 5 7 contains a spreadsheet an Orientation drop down box a Layer edit field a Column Width drop down box four tabs and several command buttons They are described below Spreadsheet The spreadsheet displays a series of columns and rows which correspond to the columns and rows of the finite difference grid By clicking the Read button the selected result type will be read and put into the spreadsheet Orientation and Layer Simulation results can be loaded layer column or row wise Orientation decides how the resu
389. sult files and saved in ASCH Matrix files An ASCH Matrix file contains a value for each model cell in a layer PMWIN can load ASCII matrix files into a model grid The format of the ASCII Matrix file 1s described in Appendix 2 In the following we will carry out the steps 1 Use the Results Extractor to read and save the calculated hydraulic heads 2 Generate a contour map based on the calculated hydraulic heads for the first layer 3 Use PMPATH to compute pathlines as well as the capture zone of the pumping well gt read and save the calculated hydraulic heads 1 Choose Results Extractor from the Tools menu The Results Extractor dialog box appears Fig 2 9 The options in the Results Extractor dialog box are grouped under four tabs MODFLOW MOC3D MT3D and MT3DMS In the MODFLOW tab you may choose a result type from the Result Type drop down box You may specify the layer stress period and time step from which the result should be read The spreadsheet displays a series of columns and rows The intersection of a row and column is a cell Each cell of the spreadsheet corresponds to a model cell in a layer Refer to Chap 5 for more detailed information about the Results Extractor For the current sample problem follow steps 2 to 6 to save the hydraulic heads of each layer in three ASCH Matrix files 2 Choose Hydraulic Head from the Result Type drop down box 3 1 in the Layer edit field For the current problem ste
390. svity instead of hydraulic conductivity from the model data file Consequently you are actually calibrating the transmissivity value as an estimated parameter defined within horizontal hydraulic conductivity For multi layer models MODFLOW requires vertical leakance instead of vertical hydraulic conductivity which is used by PMWIN to calculate the vertical leakance for MODFLOW Due to this fact automatic fit of vertical hydraulic conductivity cannot be done without modifying the inverse model or MODFLOW So if you assign an estimated parameter within vertical hydraulic conductivity you should keep in mind that you are actually calibrating the vertical leakance between two layers the layer with the estimated parameter and the underlying layer Table 3 7 Adjustable parameters through an automatic calibration within PMWIN types Parameter or excitations yes no yes no Transmissivity Horizontal hydraulic conductivity yes Vertical leakance yes opecific yield only if the simulation is transient yes Confined storage coefficient only if the simulation is transient yes Pumping or injection rates of wells yes Conductance of drain general head boundary river or stream cells yes Recharge flux yes Maximum evapotranspiration rate yes Inelastic storage factor only if the simulation is transient and the Interbed Storage package is used yes PEST Inverse Modeling Parameter List The required inputs and opt
391. t Vell c program files pm5 examples sample wel da Recharge c program files pm5 examples sample1 rch de Solver PCG2 c program files pm5 examples samplel pcqg2 c Options Check the model data Regenerate all input files for MODFLOW Generate input files only don t start UCODE 3 6 7 PMPATH Pathlines and Contours Cancel Help Fig 3 57 The Run UCODE dialog box Select this menu to call the particle tracking model PMPATH which runs independently from PMWIN Refer to Chapter 4 for details about PMPATH Note that the first time you call PMPATH it will automatically load the model currently used by PMWIN If you have subsequently modified model data and performed a flow simulation you must reload the modified model into PMPATH to ensure that it can recognize the modifications 3 7 The Tools menu PMWIN provides several modeling tools including Digitizer Field Interpolator Field Generator Results Extractor Water Budget Calculator and Graph Viewer Refer to Chapter 5 for details The Modeling Environment 3 1 The Grid Editor Processing Modflow 161 3 8 The Value menu The Value menu appears only in the Data Editor The menu items are described below Matrix Use the Browse Matrix dialog box Fig 3 58 to examine cell values The spreadsheet displays a series of columns and rows which corresponds to the columns and rows of the fi
392. t IBOUND Modflow 2 Set fixed head boundaries IBOUND 1 in layer and layer 3 use to switch Layer Copy on or off and use the Page Up and Page Down keys to switch between layers at the west and east boundaries where the river enters and leaves the model area Note that the horizontal flow component in the second layer silty layer 1s negligible so we do not need to specify fixed head cells in this layer 3 Set no flow boundaries in all layers in the areas defined by the Granite and South Granite Hills The boundaries in layers 1 and 3 should look like those in Fig 6 9 The boundaries in the layer 2 should look like those in Fig 6 10 4 Leave the Data Editor by File gt Leave Editor gt Yes Aquifer geometry The top of each aquifer slopes gradually from west to east To save you entering this data the top elevation of each aquifer has been saved as a data file gt specify the top elevation of each aquifer 1 Select Grid gt Top of Layers TOP 2 Import the file pm5 examples tutorials tutorial2 aq top dat as the elevation of the top of aquifer 1 using Value gt Matrix gt Load etc 3 Switch to Layer 2 by pressing the Page Down PgDn key Import the file pm5 examples tutorials tutorial2 aq2top dat as the elevation of the top of aquifer 2 5 Switch to Layer 3 by pressing the Page Down PgDn key 6 Import the file pm5 examples tutorials tutorial2 aq3top dat as the elevation of the top of aquifer 2
393. t Flow to a Well in a Confined Aquifer Folder pm5 examples calibration calibration3 Overview of the Problem This example gives an approximation of the Theis solution with a numerical model Given the aquifer properties transmissivity and confined storage coefficient the Theis solution predicts drawdown in a confined aquifer at any distance from a well at any time since the start of pumping The assumptions inherent in the Theis solution include 1 The aquifer is homogeneous isotropic and of uniform thickness 2 The aquifer is confined between impermeable formation on top and bottom and of infinite areal extent 3 The initial piezometric surface is horizontal and uniform 4 The pumping rate of the well is constant with time 5 The well penetrates the entire aquifer and the well diameter is small 6 Water is removed from storage instantaneously with decline in head All of these assumptions with the exception of infinite areal extent can be represented by a numerical model In this example a fully penetrating well is located at the center of the model domain and withdraws water at a constant rate The drawdown of the hydraulic head is monitored with time at a borehole 55m from the pumping well The model parameters are listed below Your task is to construct a numerical model calculate the drawdown curve at the borehole and compare it with the analytical Theis solution Initial hydraulic head 0 0 m Transmissiv
394. t Matrix Using Reset Matrix you can specify a value in a Reset Matrix dialog box The value will be assigned to all finite difference cells If you are editing a particular package in which a cell has more than one value for example the River package all values in the dialog box will be assigned to all cells Zones The Zones menu allows you to save or load the zones in or from a Zone file All zones in the layer being edited can be deleted by selecting Zones Delete All Using Zone files you can transfer zonation information between parameters or between models with different grid configuration The format of the Zone file is given in Appendix 2 Points The Points menu appears only in the Digitizer Refer to Chapter 5 for details about the Digitizer and the Points menu Search and Modify Use the Search and Modify dialog box Fig 3 61 if you want to automatically modify part of the cell data or if you want to create solid fill plots based on the cell data The items of the dialog box are described below 3 8 The Value Menu 164 Processing Modflow gt Trace Table You define a search range and its attributes in an active row of the table A row is active when the Active flag is checked The search range is given by the minimum lower limit and the maximum upper limit The color in the Color column will be assigned to the finite difference cells that have a value located within the search range You can aut
395. tal hydraulic conductivity and layer thickness to calculate transmissivity if the corresponding Transmissivity flag in the Layer Options dialog box is Calculated You can also specify transmissivity directly by choosing Transmissivity from the Parameters menu The specified transmissivity values of a model layer will be used for simulation if the Transmissivity flag is User specified See section 3 4 for more information about the Layer Options dialog box 3 5 The Parameters Menu 78 Processing Modflow Vertical Hydraulic Conductivity and Vertical Leakance As discussed in Layer Type above there are two options to input the required vertical leakance VCONT between two model layers Youcan specify the vertical leakance directly by choosing Vertical Leakance from the Parameters menu The specified Vertical Leakance values of a layer will be used for simulation if the Leakance flag in the Layer Options dialog box is User specified In the Data Editor the vertical leakance between the layers 1 and 1 1 1s given as the data of the layer 1 The vertical leakance 15 not required for the layer at the very bottom of the model because MODFLOW assumes that the bottom of the model is underlain by impermeable material Note that setting the Leakance flag in the Layer Options dialog box of a layer to Calculated causes PMWIN to calculate the vertical leakance by using eq 3 1 Effective Porosity If the total unit volume V of a soil matrix is divided
396. te the data to each model cell The model grid can be irregularly spaced Interpolation results are saved in the ASCII Matrix format see Appendix 2 which can be accepted by the Data Editor Depending on the interpolation method and the interpolation parameters the results may be slightly different With the Data Editor you can create contour maps of the interpolation results and visually choose a best result Theory is not emphasized in this description because it is introduced in an extensive literature For example Watson 1992 presents a guide to the analysis and display of spatial data including several interpolation methods Franke 1982 provides a brief review and classification of 32 algorithms Hoschek and Lasser 1992 give a comprehensive discussion of theories in geometrical data processing and extensive references in the area of data interpolation and 5 2 The Field Interpolator Processing Modflow 201 computer graphics techniques Akin and Siemes 1988 and Davis 1973 provide necessary mathematical background skills on the statistics and data analysis 1n geology Starting the Field Interpolator The Field Interpolator runs independently from PMWIN To start the program select Field Interpolator from the Tools menu of PMWIN or use the Start button on the task bar in Windows The available settings of the Field Interpolator Fig 5 1 are grouped under three tabs Hiles Grid Position and Search Gridding Method
397. tem from the Run Graphs menu The Graph Viewer Fig 5 8 allows you to examine temporal development curves of the observations and the simulation results including hydraulic heads drawdowns concentration preconsolidation heads compaction of each model layer and subsidence of an entire aquifer Note that drawdown is defined by h h where hj is the starting hydraulic head and h is the calculated head at time t The coordinates of boreholes and the corresponding observed data are specified in the Boreholes and Observations dialog box see section 3 5 PMWIN uses a bilinear interpolation scheme to calculate values at user specified boreholes For each user specified borehole the values of the four model cells surrounding that borehole are determined first The simulation results at those cells are then interpolated to obtain the value at the borehole by using the following equation X h A XA 1 h 1 104 A if h HDRY HNOFLO 5 7 5 6 The Graph Viewer Processing Modflow 211 where A is the area and h is the computed value at the center of a cell as shown in Fig 5 9 HNOFLO and HDRY are predefined heads for no flow cells and dry cells and CINACT is the predefined concentration value for inactive concentration cells If a borehole lies in an inactive cell hZHDRY 55 Drawdown Time Curves x Name Drawdown D Graph Style Linear C Semi Log
398. tforward First click the open file button E and select a PMWIN 4 x model or a MODFLOW Name File from an Open dialog box Then click the Convert button to start the conversion Refer to Appendix 3 for the definition of Name Files Telescoping Flow Model Fig 3 11 allows you to create local scale submodels from a regional model To create a submodel just select an existing PMWIN model and specify the subregion Then click the Convert button The flow simulation of existing PMWIN model must be performed The subregion is given by the starting and ending columns and rows PMWIN automatically transfers the model parameters and the calculated heads from the regional model to the subregional local model The boundary of the local model will be set to fixed head boundary for steady state simulations or time variant specified head boundary for transient simulations Indenpendent of the selected tab you can specify refinement factors for both column and row directions So you can load or create a model with a higher resolution for transport simulations 3 3 The File Menu 66 Processing Modflow J Convert Models PMWIN 4x MODFLOW 88 96 Telescoping Flow Model PMWVIN 4 x Model mdl Click the open file button to select a PMWVIN4 x model Refinement factor for columns Refinement factor for rows Fig 3 10 The Convert Models dialog box Convert Models PMWIN 4x MODFLOW 88 96 Telescoping Flow Model PM Mode
399. the BCF1 package of the original MODFLOW McDonald and Harbaugh 1988 except for the wetting and drying of cells A cell falls dry when the head is below the bottom elevation of the cell When a cell falls dry IBOUND is set to 0 which indicates a no flow or an inactive cell all conductances to the dry cell are set to zero No water can flow into the cell as the simulation proceeds and the cell remains inactive even if neighbouring water tables rise again To overcome this problem a value THRESH called wetting threshold is introduced to the BCF2 package or later versions of this package The computer code uses this value to decide whether a dry or an inactive cell can be turned into a wet active cell If THRESH 2O0 the dry cell or the inactive cell cannot be wetted 2 If THRESH lt 0 only the cell below the dry cell or inactive cell can cause the cell to become wet 3 If THRESHS gt 0 the cell below the dry cell or inactive cell and the four horizontally adjacent cells can cause the cell to become wet A dry cell or an inactive cell can be turned into an active cell if the head from the previous iteration in a neighboring cell is greater than or equal to the turn on threshold TURNON TURNON BOT THRESH 3 27 where BOT is the elevation of the bottom of the cell To keep the stability of the numerical solution a neighboring cell cannot become wet as a result of a cell that has become wet in the same iteration only
400. the No Flow zone Click the right mouse button to open the Cell Value dialog box Enter as the value for IBOUND and click OK to exit the dialog box You will notice that the cell is now gray in color jor ds ULT 4 Either repeat the above 3 steps for the remaining No Flow cells or turn on the Duplication and copy the value of IBOUND 0 to the other cells In some cases you will notice that the boundary cuts through part of a cell In these cases you need to make a judgement as to whether the cell should remain active IBOUND 1 or be specified as inactive IBOUND 0 Generally you should choose the option which applies to more than 50 of the cell area If all the steps were completed correctly the grid should now look similar to that in Fig 6 3 5 Leave the Data Editor by File Leave Editor gt Yes Aquifer geometry The next step in the process is to specify the top and bottom elevations of each aquifer in the model We need to set the aquifer top elevation to 25m and we can leave the elevation of the bottom of the aquifer as the default value of Om gt Tospecify Aquifer Top 1 Select Grid gt Top of Layers TOP 2 Since the aquifer top elevation 1s uniform throughout the model it is possible to set a single value to the entire grid by Value Reset Matrix 3 Enter 25 in the Reset Matrix dialog box and click OK to exit 4 Leave the Data Editor by File Leave Editor gt Yes Repeat the above process to set the
401. the boundary condition recharge rate and starting vertical position of particles and the vertical position of the well screen if the well is only partially penetrating A discussion about the determination of catchment areas in two and three spatial dimensions can be found in Kinzelbach et al 1992 To delineate the catchment area of a pumping well in a 3D flow field we must place enough particles around and along the well screen Fig 6 17 shows the catchment area calculated by PMPATH First 425 particles are placed around the well by using the Add New Particles dialog box the settings are NI 5 NJ 5 on faces 5 and 6 and 25 particles on the circles with R 25 and NK 15 around the pumping well Then backward tracking 1s applied for a duration of 100 years Finally the end points of the particles are saved by File Save Particles As This file can be reloaded into PMPATH by File Load Particles to display the catchment area 6 2 Determination of Catchment Areas 246 Processing Modflow Fig 6 15 Catchment area and 365 days isochrones of the pumping well 2D approach groundwater recharge is treated as distributed source within the model cells Fig 6 16 Particles are tracked back to the groundwater surface by applying the groundwater recharge on the groundwater surface 6 2 1 Determination of Catchment Areas Processing Modflow 247 Fig 6 17 Catchment area of the pumping well 3D approach 6 2 1 Determination of
402. the data given above and the model grid given in Fig 6 53 2 Geotechnical measures such as cut off wall impervious cover drain etc can be considered as an alternative Calculate flowlines for the case that a cut off wall has been built to a depth of 8m and the recharge rate within the cut off wall 1s reduced to zero by an impervious cover The location of the cut off wall is given in Fig 6 53 When calculating the flowlines particles should be started from the contaminated area 3 Repeat step 3 for the case that the cut off wall reaches the depth 10m Use a pumping well located in the cell 6 12 to capture the contaminants Calculate the required pumping rate and penetration depth Modeling Approach and Simulation Results The aquifer is simulated using a grid of 5 layers 23 columns and 23 rows All layers have the same layer type 3 confined unconfined Transmissvity varies The cut off wall is modelled by using the Horizontal flow Barriers package An impervious cover can be easily simulated by reducing the recharge rate Fig 6 54 and Fig 6 55 show the flowlines by performing forward and backward particle tracking with PMPATH The particles are initially placed in the center of each cell which is located in the first model layer and within the cut off wall It 1s obvious that the contaiminants will be washed out even if the cut off wall is going deeper The contaminated area can be captured by using a pumping well located
403. the options Head or Drawdown to decide which kind of contours should be displayed Contour level table You can click on each cell of the table and modify the values or you can click on the header button of each column of the table to change the values for all cells of the column Level To produce contours on regular intervals click the header of this column A Contour Levels dialog box allows you to specify the contour range and interval By default this dialog box displays the maximum and minimum values found in the current layer After having made your changes and clicked on OK the contour levels in the table are updated to reflect the changes Color defines the color of a contour line Clicking on the header the Color Spectrum dialog box Fig 4 8 appears Using this dialog box the contour colors can be automatically assigned so you get a gradational change from a minimum color to a maximum color To change the minimum or maximum color simply click on the button and select a color from a Color dialog box After clicking on OK a gradation of colors from the minimum to the maximum 15 assigned to each contour level Label Using the Contour Labels dialog box Fig 4 9 you can define the display frequency of contour labels First labeled contour line defines the first contour line to be labeled Labeled line frequency specifies how often of the contour lines are labeled After having made your changes and clicked on OK the flags in th
404. the parameter magnitudes DERINCLB is the absolute lower limit of parameter increments for all group members If a parameter increment is calculated as Relative or Rel to max it may become too low if the parameter becomes very small or in the case of the Rel to max option if the magnitude of the largest parameter in the group becomes very small A parameter increment becomes too low if it does not allow reliable derivatives to be calculated with respect to that parameter because of roundoff errors incurred in the subtraction of nearly equal model generated observation values DERINCLB is used to bypass this possibility If you do not wish to place a lower limit on parameter increments in this fashion you should set DERINCLB to zero Note that if INCTYP is Absolute DERINCLB is ignored FORCEN can be Always_2 Always_3 or Switch It determines how to calculate derivatives for group members If FORCEN is Always 2 derivatives for all parameters belonging to that group will always be calculated using the forward difference method If FORCEN is Always 3 PEST will use central difference method to calculate the devivatives In this case twice as many model runs as there are parameters within the group will be required however the derivatives will be calculated with greater accuracy and this will probably have a beneficial effect on the performance of PEST If FORCEN is set to Switch derivatives calculations for all adjustable group members will begin
405. the two cross sections and the head contours of layer 4 It is obvious that the cells above the groundwater surface went dry To calculate inflow into the mining site we select Tools Water Budget to calculate the water budget by assigning zone 1 to the fixed heads cells within the mining site The water budget for zone in layer 4 should look like Table 6 1 The inflow rate to the constant head cells mining site is 1 9428713E 00 m s Table 6 1 Water budget for the mining site ZONE 1 IN LAYER 4 FLOW TERM IN OUT IN OUT STORAGE 0 0000000ET00 0 0000000ET00 0 0000000E100 CONSTANT HEAD 0 0000000EF00 1 9428709ET00 1 9428709ET00 HORTA EXCHANGE 1 18420475EBT00 0 0000000ET00 1 19404 75ET00 EXCHANGE UPPER 0 0000000 00 20 0000000E X00 0 0000000E 00 EXCHANGE LOWER 7 5892387E 01 0 0000000ET00 7 58982397E 01 WELLS 0 0000000E 00 0 0000000E 00 0 0000000 00 DRAINS 0 0000000 00 0 0000000 00 0 0000000 00 RECHARGE 0 0000000 00 4 0 0000000ET00 0 0000000ET00 EI 0 0000000ET00 0 0000000ET00 0 0000000ET00 RIVER LEAKAGE 0 0000000E 00 0 0000000E X00 0 0000000E 00 HEAD DEP BOUNDS 0 0000000 00 0 0000000 00 0 0000000E 00 STREAM LEAKAGE 0 0000000 00 20 0000000E X00 0 0000000E 00 INTERBED STORAGE 0 0000000ET00 0 0000000ET00 0 0000000E400 SUM OF THE LAYER 19426 713EHOO 1 94296709ET00 4 70935716E 0 7 For task 2 all cells within the mining site are set as active cells The wetting capability of MODFLOW is turn
406. the user to assign more than one reach in different segments to the same model cell Refer to the documentation of the Streamflow Routing package Prudic 1989 for more information about the numbering scheme Streamflow LT is the streamflow entering a segment This value is specified only for the first reach in each segment The value is either a zero or a blank when the reach number Reach is not 1 When inflow into a segment 15 the sum of outflow from a specified number of tributary segments the segment inflow values are specified as 1 Stream Stage L is the head in the stream Streambed hydraulic conductance C Elevation of the Streambed Top and Elevation of the Streambe Botton are used to calculate leakage to or from the aquifer through the streambed is calculated in the same way as Cay of the River package see 3 21 Width of the Stream Channel Slope of the Stream Channel and Manning s roughness coeff n C are used only when the option Calculate stream stages in reaches is checked The cross sectional shape of the stream channel is assumed to be rectangular Slope of the Stream Channel is the slope of the stream channel in each reach Manning s roughness coeff n C is a value resulting from the Mannings roughness coefficient n divided by a conversion factor C Some of the experimental values of the Manning s roughness coefficient can be found in the documentation of the Streamflow Routing package The value of the conve
407. timized parameter values which are saved in a separate file ucode st Similar to PEST you can create a scatter diagram to present the calibration result see above Note that PMWIN does not retrieve the optimized parameter values into the data matrices Your PMWIN model data will not be modified in any way This provides more security for the model data because an automatic calibration process does not necessarily lead to a success If 2 3 2 Perform Automatic Calibration with UCODE 50 Processing Modflow you want to operate on a calibrated model you can import the model by choosing Convert Model from the File menu see Chapter 3 for details List of Calibration Parameters UCODE Run UCODE hy c progra e myprog32 ucode bin mrdrive exe a Generate Description Destination File 8 na BASIC Package _ c pm5data sample1 bas dat Fig 2 41 The Run UCODE dialog box 2 3 2 Perform Automatic Calibration with UCODE Processing Modflow 51 2 4 Animation You already learned how to use the Presentation tool to create and print contour maps from calculated head and concentration values The saved or printed images are static and ideal for paper reports In many cases however these static images cannot ideally illustrate motion of concentration plumes or temporal variation of hydraulic heads or drawdowns PMWIN provides an animation technique to display a sequence of the saved images
408. ting for irregularly distributed data points ACM Transactions on Mathematical Software 4 160 164 Akin H and H Siemes 1988 Praktische Geostatistik Springer Verlag Berlin Andersen P F 1993 A manual of instructional problems for the U S G S MODFLOW model Center for Subsurface Modeling Support EPA 600 R 93 010 Anderson M P 1979 Using models to simulate the movement of contaminants through ground water flow systems Critical Reviews in Environmental Control 9 2 97 156 Anderson M P 1984 Movement of contaminants in groundwater groundwater transport advection and dispersion In Groundwater Contamination National Academy Press Washington DC pp 37 45 Anderson M P and W W Woessner 1991 Applied groundwater modeling simulation of flow and advective transport 381 pp Academic Press San Diego CA Ashcraft C C and R G Grimes 1988 On vectorizing imcomplete factorization and SSOR preconditioners SIAM Journal of Scientific and Statistical Computing v 9 no 1 p 122 151 Axelsson O and G Lindskog 1986 On the eigenvalue distribution of a class of preconditioning methods Numerical Mathematics 48 479 498 Baetsle L H 1967 Computational methods for the prediction of underground movement of radio nuclides J Nuclear Safety 8 6 576 588 Bear J 1972 Dynamics of fluids in porous media American Elsevier Pub Co New York Bear J 1979 Hydraulics of Groundwater McGraw Hill N Y
409. tion Results The west boundary of the model is impervious and the river to the east 1s simulated by the fixed head boundary condition IBOUND 1 with the initial head at 10 m There are no natural boundaries to the South and North so we have to use streamlines as impervious boundaries The distance of the selected streamline from the well must be large enough so that the hydraulic head at these boundaries are not affected by the pumping well This is the case if the total recharge in the chosen strip is considerably larger than the pumping rate of the well Because of the symmetry of the system we could use one half of the model area only To show the whole catchment area we decided to use the entire model area The aquifer is simulated using a grid of one layer 50 rows and 51 columns A regular grid space of 50 m is used for each column and row The layer type is 1 unconfined Fig 6 15 shows the contours the catchment area and the 365 days isochrones of the pumping well using a 2D approach where the groundwater recharge is treated as a distributed source within the model cells and 50 particles are initially placed around the pumping well in the middle of the aquifer If the groundwater recharge 1s applied on the groundwater surface refer to RCH EVT options in chapter 4 for this option particles will be tracked back to the groundwater surface Fig 6 16 We can easily imagine that the size and form of the calculated catchment area depend on
410. tion factor specified in the Properties tab of the Add New Particles dialog box Once particles are placed their color and retardation factor cannot be changed any more Add New Particles E3 Particles Properties Cell Faces Particles on cell faces Particles within cells Feei NxNQg 3x fl 2 Face2 NIxNK Face3 NJxNK 3x fl Ne Face 4 NJxNK B x fr Pericles on E FaceS NIxNJ 3x fl EMEN Face 6 NixNJ 3 xy fi Nh Cancel Fig 4 6 The Add New Particles dialog box The retardation factor R is defined by 4 2 PMPATH Modeling Environment Processing Modflow 185 R 1 Kj 4 8 where p is the bulk mass density of the porous medium n is the effective porosity and K is the distribution coefficient A detailed description of these parameters can be found in the literature e g Freeze and Cherry 1979 The retardation factor was first applied to groundwater problems by Higgins 1959 and Baetsle 1967 Baetsle indicated that it may be used to determine the retardation of the center of mass of a contaminant moving from a point source while undergoing adsorption PMPATH uses the retardation factor to modify the average pore velocity of the eroundwater flow The velocity vectors in equation 4 3a 4 3f become Va Q nAy Az R 4 9a Vio Q mAy Az RH 4 9b v Q rAxAz R 4 9c Vo Q rx AZ 4 9d V Q mAx
411. to linear sorption For very small values of D the left hand side of eq 3 48 becomes negligible i e there is no change in the sorbed concentration and sorption is negligible gt First order kinetic dual domain mass transfer Dual domain means that two kinds of continuum e g a fractured medium and the porous medium exist simultaneously in the same spatial region 1 the same model cell In fractured aquifers the water moves faster along fractures than it does in a rock formation and the solute transport is often controlled by advection along the fractures and dominated by dispersion in the porous block along the fractures MT3DMS uses the dual domain concept to approach extremely heterogeneous porous media or media composed of fractures and pores In this approach the effective porosity specified in Parameters Effective Porosity is used as the primary porosity for the pore spaces filled with mobile water 1 e fractures and the secondary porosity for the pore spaces filled with immobile water 1 e rock formation is defined in the Chemical Reaction MT3DMS dialog box Fig 3 50 The sum of the primary and the secondary porosities is the total porosity of the medium The exchange of solutes between the mobile and immobile domains can be defined through eq 3 50 aC ds E 3 50 where nj is the secondary porosity 1 e the portion of total porosity filled with immobile water C ML is the concentration in the m
412. to vertical 10 hydraulic conductivity is 20 to 1 0 Cells with assigned constant head of 25 feet Elevation in feet above arbitrary datum column 1 2 3 4 recharge cells Plan View Vas x x DX DX aS Vas pt ttt infiltration pone Fig 6 22 Hydrogeology and model grid configuration Reasonable solutions to the ground water mounding problem can be obtained in two steady state simulations by using the PCG2 solver In the first simulation dry cells are converted to wet by comparison of the wetting threshold THRESH to heads in underlying cells only which is 6 2 4 Simulation of a Water Table Mound resulting from Local Recharge Processing Modflow 255 indicated by a negative value of THRESH The wetting iteration interval is 1 and THRESH 15 0 5 foot which means that the wetting threshold is 10 percent of the thickness of a cell In the second simulation wetting of cells is based on comparison to heads both in horizontally adjacent and underlying cells THRESH is positive A wetting iteration interval of 2 and a THRESH of 1 5 feet are used in order to prevent continued oscillation between wet and dry for some cells Due to the steepness of the head gradient and the grid discretization the head difference between adjacent horizontal cells 15 generally much larger than the head differ
413. u intend to calibrate the pumping rate of wells or the conductance of head dependent cells e g drain general head boundary river or stream cells you must also assign a non zero pumping rate or conductance to those cells Pumping rate or conductance values will not be adjusted 1f the user specifed values are equal to zero 3 Use the List of Calibration Parameters UCODE dialog box to activate the estimated parameter and to specify the necessary values Note that for layers of type 0 confined and 2 confined unconfined transmissivity const MODFLOYW reads transmissvity instead of hydraulic conductivity from the model data file Consequently you are actually calibrating the transmissivity value as an estimated parameter defined within horizontal hydraulic conductivity For multi layer models MODFLOW requires vertical leakance instead of vertical hydraulic conductivity which is used by PMWIN to calculate the vertical leakance for MODFLOW Due to this fact automatic fit of vertical hydraulic conductivity cannot be done without modifying the inverse model or MODFLOW So if you assign an estimated parameter within vertical hydraulic conductivity you should keep in mind that you are actually calibrating the vertical leakance between two layers the layer of the estimated parameter and the underlying layer 3 6 6 UCODE Inverse Modeling Processing Modflow 155 UCODE Inverse Modeling Parameter List The required inputs an
414. ues For example if Add is used the user specified value will be added to the cell value The Parameter drop down box shows the available parameter type s You may select the parameter to which the subsequent Search and Modfiy operation will be applied i Cell Information Cell position 25 15 Top of layer 0 o ooo Bottom of layer 6 Initial Head Initial Concentraton 0 Horizontal K 000 Transmissivity 001 1 Vertical K Vertical leakance Specific storage Storage Coefficient Effective porosity 25 Specific Yield only used by transient flow simulations I will not be used for the current layer Fig 3 7 The Cell Information dialog box 3 2 The Data Editor 62 Processing Modflow amp Search and Modify Cell Values Parameter Horizontal Hydraulic Conductivity Value 0001 Search Range Options C Replace Min 0001 C Add Cancel C Mex 0001 RUP Display Only Help Fig 3 8 The Search and Modify Cell Values dialog box 3 2 2 The Zone Input Method The Zone Input Method allows you to assign parameter values by zones To activate this method choose Input Method Zones from the Options menu Alternatively you may click on the button Zones must be designed or drawn first before assigning parameter values to them gt To draw a zone 1 Click the assign value button
415. uifer Because horizontal flow in the confining bed 1s small compared to horizontal flow in the aquifers and storage 1s not a factor in steady state simulations the confining bed is not treated as a separate model layer The effect of the confining bed 1s incorporated in the value for vertical leakance see section Fig 3 15 Note that if storage in the confining bed were significant transient simulations would require that the confining layer be simulated using one or more layers The confining layer must also be simulated if you intend to calculate pathlines with PMPATH or to simulate solute transport A uniform horizontal grid of 10 rows and 15 columns is used Aquifer parameters are specified as shown in Fig 6 21 6 2 3 Simulation of a Two Layer Aquifer System Processing Modflow 251 150 areal recharge Conceptual Model F 0 004 ft d Potentiometric surface ji E Upper aquifer 25 2222 sl Lower aquifer S 50 Cross sectional model configuration 100 Layer 1 2 _ tivity 10 feet per wy 50 Con yy Vertical pur 1o 001 per day 2 Elevation feet above arbitrary datum 0 Layer 2 Transmissivity 2 500 feet sequared per day 50 Plan View Cell dimensions 500 feet by 500 feet SS PUN u 5
416. ulation over several stress periods the length of the period 9 46728E 07 seconds 1s given as the observation time Click OK to close the dialog box 2 3 Automatic Calibration 46 Processing Modflow Boreholes and Observations xi 9 46726E 0 ce Name Time 2 9 46726E 0 3 9 46726E 0 4 9 46726E 0 0 ce 2 oo 0 0 0 0 0 0 0 0 2 oOo oo Options Use observed heads for the calibration Use observed drawdowns for the calibration Save Load Clear Cancel Help Fig 2 36 The Boreholes and Observations dialog box 2 3 1 Perform Automatic Calibration with PEST gt specify the starting values for each parameter 1 Choose PEST Parameter List from the Models menu A List of Calibration Parameters PEST dialog box appears The options of the dialog box are grouped under five tabs Parameters Group Definitions Prior Information Control Data and Options 2 In the Parameters tab activate the first parameter by setting the Active flag to from Parameters table and enter values shown in Fig 2 37 into the table PARVAL1 is the initial guess of the parameter PARLBUD is the lower bound and PARUBUD is the upper bound of the parameter gt perform the automatic calibration 1 Choose PEST Inverse Modeling gt Run from the Models menu The Run PEST dialog box
417. uming that the parameters are random variables Hydraulic conductivity or transmissitivity is commonly assumed to be lognormally distributed We denote the hydraulic conductivity by X and a variable Y log X When Y is normally distributed with a mean value and standard deviation then X has a lognormal distribution Starting the Field Generator The Field Generator runs independently from PMWIN To start the program select Field Generator from the Tools menu of PMWIN or use the Start button on the task bar in Windows A dialog box appears Fig 5 6 The program uses the correlation scales in both I and J directions and the mean value and standard deviation of log transformed measurement values to generate a quantitative description a realization of the hydraulic conductivity or transmissivity field The size of the field number of cells and the number of desired realizations 1s specified in the dialog box Realizations are saved in the ASCII Matrix format see Appendix 2 using the file names filename xxx where filename 1s the output file name specified in the dialog and xxx 1s the 5 3 The Field Generator Processing Modflow 207 realization number Note that filename should not be the same as the name of vour model because PMWIN uses the same convention to save some internal data files Output file name c pmwin examples pmex pm5_1 field r Parameters Number of Realizations 1 to 999 10 Mean Valu
418. unction between successive optimization iterations is less than PHIREDSWH PEST will switch to three point derivatives calculation for those parameter groups with FORCEN Switch The relative reduction in the objective function is defined by where Q is the objective function calculated on the basis of the upgraded parameter set determined in the 1 th iteration A value of 0 1 1s often suitable for PHIREDSWH If itis set too high PEST may make the switch to three point derivatives calculation too early The result will be that more model runs will be required than are really needed at that stage of the estimation process If PHIREDSWH is set too low PEST may waste an optimization iteration or two in lowering the objective function to a smaller extent than would have been possible if it had made an earlier switch to central derivatives calculation Note that PHIREDSWH should be set considerably higher than PHIREDSTP see below which sets one of the termination criteria on the basis of the relative objective function reduction between optimization iterations NOPTMAX is the maximum number of optimization iterations A value of 20 to 30 is often adequate If you want to ensure that PEST termination 15 triggered by other criteria more indicative of parameter convergence to an optimal set or of the futility of further processing you should set this variable very high PHIREDSTP and NPHISTP are convergence criteria For man
419. undwater is computed in a manner identical to the River package see below The Reservoir package is ideally suited for cases where leakage from or to reservoirs may be a significant component of flow in a groundwater system however if reservoir stage is unknown then a more complex conceptualization would be needed in which reservoir stage would be computed as part of the simulation rather than having stage specified as model input For reservoirs where stage is unknown a program that computes the stage in lakes based on inflows and outflows has been written by Cheng and Anderson 1993 Reservoir Package Ea Reservoir Number Land Surface Elevation L 5 Reservoir bed vertical hydr Conductivity L T n Thickness ofthe Reservoir bed ph Layer Indicator 7 Parameter Number D Connection Options C Reservoir connected to the top layer Reservoir connected to highest active cell C Vertical distribution of reservoir is specified in IRESL Current Position Column Row 22 12 he connection option is applied to the entire matrix IRESL is only required if the hird connection option is selected Stage x Cancel Help Fig 3 21 The Reservoir Package dialog box Three options are avaliable for simulating leakage between a reservoir and the underlying eroundwater system The first option simulates leakage only to layer 1 the second option simulates leakage to the uppermost active c
420. ure To specify the well data Select Models MOFLOW Well Switch to Layer 3 by pressing the PgDn key twice Move the grid cursor to Well 1 by clicking on it with the left mouse button and set the pumping rate to 500 m day by bringing up the Cell Value dialog box with the right mouse button Repeat the above step with Well 2 and Well 3 Leave the Data Editor by File Leave Editor Yes 6 1 2 Tutorial 2 Confined and Unconfined Aquifer System with River 240 Processing Modflow Step 5 Perform steady state flow Simulation gt Torun the flow simulation Select Models gt MODFLOW Run 2 Click OK in the Run Modflow dialog box to generate the required data files and to run MODFLOW you will see a DOS window open and MODFLOW perform the iterations required to complete the flow simulation 3 Press any key to exit the DOS Window Step 6 Extract and view results gt produce head contours 1 Using the Results Extractor save the hydraulic head data as T2S1 DAT and 252 and T2S3 DAT for Layer 1 2 and 3 respectively 2 Select Tools Presentation and load the saved data into each layer Alternatively you may open the Results Extractor dialog box within the Data Editor by Value gt Result Extractor In this case the Results Extractor dialog box will contain an additional Apply button which allows to put the data from the Results Extractor to the model grid directly 3 Use Options gt Environment
421. using the forward difference method switching to the central method for the remainder of the estimation process after the relative objective function reduction between successive iterations 1s less than PHIREDSWH as defined in the Control Data see below Experience has shown that in most instances the most appropriate value for FORCEN is Switch This allows speed to take precedence over accuracy in the early stages of the optimization process when accuracy is not critical to objective function improvement and accuracy to take precedence over speed later in the process when realization of a normally smaller objective function improvement requires that derivatives be calculated with as much accuracy as possible especially if parameters are highly correlated and the normal matrix thus approaches singularity DERINCMUL If a three point derivatives calculation is employed the value of 3 6 5 PEST Inverse Modeling 146 Processing Modflow DERINC is multiplied by DERINCMUL If you do not wish the parameter increment DERINC to be changed you must set DERINCMUDL to a value of 1 0 Alternatively if for some reason you wish the increment to be reduced if three point derivatives calculation is employed you should provide DERINCMUL with a value of less than 1 0 Experience shows that a value between 1 0 and 2 0 is usually satisfactory DERMTHD defines the variant of the central ie three point method used for derivatives calculation and is used
422. vel table can be load from or save in separate Contour files Refer to Appendix 2 for the format i Color Spectrum x Minimum Color Maximum Color gt EN OK Cancel Fig 4 8 The Color Spectrum dialog box Contour Labels First labeled contour line Labeled line frequency Cancel Fig 4 9 The Contour Labels dialog box Label Format Fixed C Exponential Decimal digits 2 Frefix Suffix m Cancel Fig 4 10 The Label Format dialog box 4 3 PMPATH Options Menu Processing Modflow 191 Particle Tracking Time The available settings of the Particle Tracking Time dialog box Fig 4 11 are grouped under 3 tabs namely Simulation Mode Time Pathline Colors and RCH EVT options These tabs are described below Particle Tracking Time Properties x Simulation Mode Time Pathline Colors RCH EVT Options Current Time Tracking Step Unit seconds Stress Period 1 Step Length 31557600 Time Step 1 Maximum steps 100 Time Mark mPlan View Cross Sections Interval 1 visible Visible Size 10 Size 3 Simulation Mode Flowlines use the flow field from the current time step Patines transientilow elds Stop Condition Iv Particles stop when they enter cells with internal sinks Particles sta e Simulation tine little reached Fi
423. ver a time interval of length At T Q Vez 4 Vz 74 AN 22 Qe y2 22 y Q E M 5 x1 x Qe z 2 y Vy y V X X Fig 4 2 Flow through a unit volume of a Fig 4 3 Finite difference approach porous medium x1 y1 z1 Eq 4 2 1s the mass balance equation for a finite difference cell The left hand side of eq 4 2 represents the net mass rate of outflow per unit volume of the porous medium and the right hand side is the mass rate production per unit volume due to internal sources sinks and mass storage Substitution of Darcy s law for each flow term in eq 4 2 ie Q9Ah K A Ax yields an equation expressed in terms of unknown heads at the center of the cell itself and adjacent cells An equation of this form is written for every cell in the mesh in which head is free to vary with time Once the system of equations is solved and the heads are obtained the volume flow rates across the cell faces can be computed from Darcy s law The average pore velocity components across each cell face are Ya m n Ay 2 4 3a Vio Qo n Ay 2 4 3b Vy Q n Ax Az 4 3c V2 Nn Ax Az 4 3d Q n Ax Ay 4 3e Vo n Ax Ay 4 3 4 1 The Semi analytical Particle Tracking Method 178 Processing Modflow where n 1s the effective porosity and Vias Vyas and V7 LT are the average pore
424. ween model layers 1 and 2 The vertical leakance is assumed to be 0 0002 per day In areas not covered by the pond recharge 1s applied areally at a rate of 0 001 foot per day to simulate natural recharge Recharge option Recharge is applied to the highest active cell 1s used so that recharge will penetrate through 6 2 5 Simulation of a Perched Water Table Processing Modflow 259 inactive cells to the water table A recharge rate of 0 01 foot per day is applied to the area covered by the pond A steady state simulation is performed to simulate the formation of a perched water table Solution of the flow equation is obtained using the SIP solver Starting hydraulic head in layer 1 under the pond is set at 21 feet All other cells in layer 1 initially are specified as no flow cells The wetting iteration interval THRESH and wetting factor are set at 2 iterations 1 0 foot and 0 5 foot respectively se MODFLOW gt Wetting Capability A positive value of THRESH indicates that horizontally adjacent cells can cause dry cells to become wet This is the only way for cells in layer 1 to become wet because heads in layer 2 are always below the bottom of layer 1 Fig 6 25 shows the contours of steady state heads in layer Steady state heads along row 1 in layer 1 range from 29 92 feet in the cell 1 1 1 to 20 84 feet in cell 40 1 1 i 240 2 18 O SAQ we ex 94 Fig 6 25 Simulated steady state head distribution in
425. wn which makes the well cells fall dry This in turn switches off the well and leads to a rise of the water table and wetting of the well cell etc The user can detect such situations by examining the model run record file 3 6 1 MODFLOW 100 Processing Modflow OUTPUT DAT a message is printed each time a cell converts Refer to the documentation of the BCF2 package for how to solve problems with convergence MODFLOW Output Control The Output Control menu is used to control the frequency and terms of simulation results of MODFLOW that will be printed or saved Various simulation results can be saved in files by checking the corresponding output terms in the MODFLOW Output Control dialog box Fig 3 28 The simulation results are saved whenever the time steps and stress periods are an even multiple of the output frequency and the results for the first and last stress periods and time steps are always saved Use zero for the output frequency if only the result of the last stress period or the last time step should be saved The predefined heads for no flow cells HNOFLO and dry cells HDRY are given in the Predefined Head Values group The output terms and the corresponding result files are described below All result files are saved in the folder in which your model data are saved mA OK 9 Iv Drawdowns Cancel Iv Cell by cell Flow Terms Iv Subsidence from IBS1 Help Iv Compaction of Individual Layers from IBS1
426. x HE A m Click on to open the Load Matrix dialog box and select the appropriate file to load in this case itis TISS DAT Click OK 6 1 1 Tutorial 1 Unconfined Aquifer System with Recharge 228 Processing Modflow 5 Exit the Load Matrix dialog box by clicking on OK 6 The data will appear in the Browse Matrix dialog box click on OK to exit this dialog box The data 1s now loaded 7 Leave the Data Editor by File Leave Editor gt Yes Time Parameters We now need to change from a steady state simulation to a transient simulation In the transient simulation there are two stress periods one of 240 days when pumping is occurring and no recharge and the other of 120 days when there is recharge only It is possible to have different conditions for each stress period as will be demonstrated below v To change to a transient simulation Select Parameters Time to open the Time Parameters dialog box Change the model to transient by clicking on Transient in the Simulation Flow Type box Activate the second period by checking the Active box in the second row of the table E E S ox Change the period length and time steps such that For period 1 Period Length 240 Time Step 12 For period 2 Period Length 120 Time Step 6 5 Click OK to exit the Time Parameters dialog box Pumping rates Now we need to set the pumping rate for each well during stress period 1 gt set the pumping rate 1 Select Models
427. x file Grid Position Using the rotation angle and the coordinates X Y of the left corner of the model grid you may rotate and place the grid at any position The rotation angle 1s expressed in degrees and is measured counterclockwise from the positive x direction See section 3 9 for details about the coordinate system of PMWIN As we normally define the grid position and the coordinate system at the beginning of a modeling process the grid position will rarely be changed here Gridding Method PMWIN provides four gridding methods namely Shepard s inverse distance method Akima s bivariate interpolation method Renka s triangulation method and the Kriging method You can select a method from the drop down box For each gridding method there is a corresponding interpolation program The interpolation programs are written in FORTRAN and were compiled with a 32 bit compiler Shepard s inverse distance The Shepard s inverse distance method uses eq 5 1 to interpolate data for finite difference cells i 1 c 5 1 gt 1 i 1 Where d is the distance between data point 1 and the center of a model cell f is the value at the i th data point F is the weighting exponent and f is the estimated value at the model cell The weighting exponent must be greater than zero and less than or equal to 10 Fig 5 2 shows the effects of different weighting exponents Five data points are regularly distributed along the x axis Usin
428. y cases 0 01 and 3 are suitable values for PHIREDSTP and NPHISTP respectively If 1n the course of the parameter estimation process there have been NPHISTP optimization iterations for which i nin SS MEN PHIREDSTP 3 57 i Q being the objective function value at the end of the i th optimization iteration and being the lowest objective function achieved to date PEST will end the optimization process NPHINORED is the first termination criterion A value of 3 is often suitable If PEST has 3 6 5 PEST Inverse Modeling Processing Modflow 151 failed to lower the objective function over NPHINORED successive iterations the program stops RELPARSTP and NRELPAR represent the second termination criterion If the magnitude of the maximum relative parameter change between optimization iterations 15 less than RELPARSTP over NRELPAR successive iterations the program stops The relative parameter change between optimization iterations for any parameter is calculated using equation 3 55 For many cases a value of 0 01 for RELPARSTP and a value of 3 for NRELPAR is adequate Options When the optimization process 1s complete one of the termination criteria having been met or perhaps another termination criterion such as zero objective function or zero objective function gradient for which no user supplied settings are required PEST writes some information concerning the optimized parameter set to its run record fi
429. y of the model and the consistency of the model data given in table 3 5 if this option is checked The errors if any are saved in the file CHECK LST located in the same folder as your model data gt Click OK to start the generation of the MODFLOW and PEST input files In addition PMWIN generates two batch files PEST BAT and MODELRUN BAT in your model folder When all necessary files are generated PMWIN automatically runs PEST BAT in a DOS window The other batch file MODELRUN BAT will be called by PEST After completing the parameter estimation process PEST prints the optimized parameter values to the run record file PESTCTL REC in your model folder and writes the optimized parameter values to the corresponding input files of MODFLOW BCF DAT WEL DAT etc The simulation results of MODFLOW are updated by using these parameter values Note that PMWIN does not retrieve the optimized parameter values into the data matrices Your PMWIN model data will not be modified in any way This provides more security for the model data because an automatic calibration process does not necessarily lead to success If you want to operate on a calibrated model you can import the calibrated MODFLOW model by choosing Convert Model from the File menu Run PEST Basic Package Block Centered Flow BCF1 2 Output Control _ Well c program files pm5 examples sample1 wel da Recharge cAprogram filesxpm5Yexamplesisamplel rch da
430. yer 1 simulates the upper geohydrologic unit and is assigned a hydraulic conductivity of 5 feet per day The bottom of layer is at an elevation of 20 feet The lower geohydrologic unit is simulated as model layer 2 This layer is simulated as a confined unconfined layer with constant transmissivity layer type 2 The top and bottom elevations of layer 2 are set at 10 and 0 feet respectively Because the head in this layer is always below the layer top the flow from above is limited as described by McDonald and Harbaugh 1988 p 5 19 Thus there is no direct hydraulic connection between the perched layer and the lower layer 6 2 5 Simulation of a Perched Water Table 258 Processing Modflow Model Grid Configuration Cross Section infiltration pond pond leakage Perched groundwater moune Elevation in feet above arbitrary datum Assigned constant head of 1 foot cell dimensions 1eftby 16 ft Plan View modeled quarte Fig 6 24 Hydrogeology and model grid configuration but the perched heads have a direct impact on the recharge into the lower layer All cells in layer 2 are assigned a constant head of 1 foot because there is no need to simulate heads in this layer for the purpose of estimating recharge The middle geohydrologic unit is not simulated as a separate model layer because it is assumed that horizontal flow and storage effects are negligible This unit is represented by the value for vertical leakance bet
431. ype source boundary condition in a steady state flow field numerical results were compared with the analytical solution of Wexler 1992 PM5 TRANSPORT9 This model is described in the section MODEL TESTING AND EVALUATION Three Dimensional Steady Flow of the user s guide of MOCS3D A numerical model consisting of 12 columns 32 rows and 40 layers is used to simulate three dimensional transport having a permanent point source in a steady state flow field numerical results were compared with the analytical solution of Wexler 1992 PM5 TRANSPORT10 This model is described in the section MODEL TESTING AND EVALUATION Two Dimensional Radial Flow and Dispersion of the user s guide of MOC3D A numerical model consisting of 30 columns 30 rows and 1 layer is used to simulate two dimensional transport having a permanent point source in a steady state radial flow field numerical results were compared with the analytical solution given by Hsieh 1986 PM5 TRANSPORT11 This model is described in the section MODEL TESTING AND EVALUATION Point Initial Condition in Uniform Flow of the user s guide of MOC3D A numerical model consisting of 26 columns 26 rows and 26 layer is used to simulate three dimensional transport having an initial point source in a parallel steady state flow at 45 degrees to the x direction numerical results were compared with the analytical solution given by Wexler 1992 The point source was simulated at column 4 r

Manual - Group of Computational Hydrosystems

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