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manual of PMWIN4.1

1. Fig 3 31 The MT3D Output Control dialog box with the Output Time table The Modeling Environment 3 44 Processing Modflow 3 3 5 The Source Menu The source menu is used for specifying the concentration of point or areally distributed sources or sinks You specify the concentration of a particular source or sink by using the Data Editor Point sources include wells general head boundary cells constant head cells and rivers or streams Recharge is the only areally distributed source whereas evapotranspiration is the only sink whose concentration can be specified 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 by MT3D Note that MT3D does not allow the concurrent use of the River Package RIV1 and the Streamflow Routing Package STR1 This does not cause problems in any case because the STR1 Package has all functionality of the RIV1 Package Menu items of the Source menu are dimmed if the corresponding hydraulic features given in the Packages 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 item of the Source menu is checked If a checked item is no longer necessary for a tran
2. Fig 3 35 Active bores and the bore number The Modeling Environment Processing Modflow Processing Modflow 3 61 3 3 7 The Value Menu The Value menu appears only in the Data Editor The menu items are described below Matrix There are two items Reset and Browse in the submenu Matrix gt Reset Using Reset you can specify a value in the Reset Matrix dialog box Fig 3 36 The value will be assigned to all finite difference cells in the current layer If you are editing a particular package in which a cell has more than one value e g River Package as shown in Fig 3 37 all values in the dialog will be assigned to all cells in the current layer Elevation of the Layer Bottom L Hydraulic Conductance of the Riverbed L 2 T 001 Head in the River L C 12 Elevation of the Riverbed Bottom L 10 oe Fig 3 37 The Reset Matrix dialog box for the River Package gt Browse Using Browse you can examine cell values in the Browse Matrix dialog box Fig 3 38 The spreadsheet displays a series of columns and rows which are corresponding to the columns and rows of the finite difference grid The cell data are shown in the spreadsheet If you are editing a particular package in which a cell has more than one values e g River Package you can select
3. PMPATH SAMPLE MDL d File Run Options Help ERREK k e elal 4 739E 02 3 251E 02 2 554E 00 24 141 8 1081E 00 49538E 05 1 5800E 08 1 1 0 22 33 12 Fig 2 22 The sample model loaded in PMPATH Your First Groundwater Flow Model with PMWIN Processing Modflow Particle Placement Fig 2 23 The Particle Placement dialog box File Run Options Help Fig 2 24 The capture zone of the pumping well Your First Groundwater Flow Model with PMWIN Processing Modflow 2 23 Particle Tracking Options Fig 2 25 Particle tracking options PMPATH SAMPLE MDL File Run Options Help AHHAA AAALRECIE Fig 2 26 100 days capture zone calculated by PMPATH Your First Groundwater Flow Model with PMWIN Processing Modflow 3 1 3 The Modeling Environment PMWIN assumes that you are using consistent units throughout the modeling process For example if you are using length L units of feet and time T units of days hydraulic conductivity will be expressed in units of ft d pumping rates will be in units of ft d and dispersiv
4. gt Help Cancel OK Fig 3 9 The Layer Options dialog box 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 Type 0 The 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 The 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 A layer of this type is partially convertible between confined 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 is constant throughout the simulation Vertical leakage from above is limited if the layer desaturates Type 3 A layer of this type is fully convertible between confined and unconfined Confined storage coefficient specific storage x layer thickness is used to calculate the rate of change in storage if the layer is fully saturated otherwise specific yield
5. where Q L T is the stream discharge calculated by STR1 n is Manning s roughness coefficient w L is the width of the channel S LL is the slope of the stream channel and C is a constant see equation 3 12 Recharge RCH1 The Recharge Package is designed to simulate areally distributed recharge to the groundwater system Recharge is defined by assigning the following data to model cells in the Recharge RCH1 dialog box Fig 3 15 Recharge Flux LT Layer Indicator Ipc The specified values and Ipc are shown on the Statusbar of the Data Editor Note that although lp and Ic are specified for each vertical column of cells you are allowed to move to other layers within the Data Editor and examine the grid configuration in each layer Recharge RCH1 Recharge Flux L T 2 5E 09 Layer Indicator arct 0 Cancel Recharge Options Recharge is only applied to the top grid layer Vertical distribution of recharge is specified in IRCH Recharge is applied to the highest active cell urrent Row 9 he recharge option is applied to the entire matrix IRCH is only fadura if the second recharge option is selected carn Column 14 C Fig 3 15 The Recharge RCH1 dialog box MODFLOW uses to calculate the recharge flow rate Q L T applied to the model cell Q 1 DELR DELC 3 15 where DELR DELCis the map area of a model cell The recharge rate Q is applied
6. 3 3 3 The Parameters Menu Time You specify temporal parameters in the Time Parameters dialog box as shown in Fig 3 10 To activate a stress period click the Active flag and set it to YES The temporal parameters include the time unit the length of stress periods and the numbers of stress periods time steps and transport steps In MODFLOW the simulation time is divided into stress periods which are in turn divided into time steps In the MT3D model each time step is further divided into smaller time increments called transport steps Time Parameters Simulation Time Unit days i Auto Update Period Length Steady State Transient gt Simulation Flow Type Total Period Number 3 Total Time Steps 30 Total Simulation Time 3 E 3 days Fig 3 10 The Time Parameters dialog box 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 PMWIN allows you to perform steady state or transient flow simulations by selecting a corresponding option from the Simulation Flow Type group You can run a steady state simulation over several stress periods In this case a steady state solution is calculated for each stress period For each stress period you have the option of changing parameters associated with head dependent boundary conditions in the River
7. 65 5 68 0 51 5 515 51 0 151 0 50 5 450 5 50 0 50 0 49 5 449 5 49 0 b i i i i 49 0 65 66 0 66 5 67 0 675 68 0 measurement point 500m Fig 5 9 Contours produced by the Kriging method Applications and Sample Problems 5 10 65 5 67 0 67 5 68 0 515 66 0 66 5 515 67 0 Fig 5 10 Contours produced by Akima s bivariate interpolation lt measurement point 66 0 66 5 67 67 5 68 0 o 2 50 5f 49 5 fiver 0 wet lt ore doo o gt 515 a 0 50 5 949 5 wol 65 66 0 665 67 0 Fig 5 11 Contours produced by Renka s triangulation algorithm measurement point Applications and Sample Problems Processing Modflow Processing Modflow 5 11 655 66 0 66 5 67 0 67 5 68 0 515 515 51 0 51 0 50 5 1505 Ly hi z 50 0 450 0 Sh 49 54 449 5 490 i 49 0 65 5 66 0 66 5 67 0 675 68 0 gt measurement point o 50m Fig 5 12 Contours produced by SURFER The inverse distance method is used Applications and Sample Problems 5 12 Processing Modflow 5 5 An Example of Stochastic Modeling Location PMWIN EXAMPLES SAMPLE Problem Description and Modeling Approach Aquifer remediation measures are often designed by means of groundwater models Mode
8. Search Level Minimum Maximum Co 10 60 Fig 3 44 The Search Level dialog box 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 gt Maps You can display DXF background maps by using a Maps Options dialog box See section 3 3 8 for details 3 3 8 The Options menu There are four menu items in the Options menu viz 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 gt Environment The Environment Options dialog box Fig 3 45 allows you to configure the coordinate system and the appearance of the model grid The available settings are summarized in four groups viz Grid Appearance Grid Position Worksheet Size and Contours Check the Display zones in the cell by cell mode box if you want to see the user specified zones in the cell by cell mode Environment Options Grid Appearance Worksheet Coordinate Syst O X Gria XX well discharge arkeheet Coordina DRTE J Inactive Cells I well recharge Fixed Head Drain DX GHB Cells xX River Stream DX Wall HFB X Bores Grid Position Worksheet Size Xo 349 43 x1 0 Yo 2963 18 vi 0 A 0 x2 4000 A Rotation angle in degree ye 4000 bea X1 Y1 Y X0 Yo Contours Displa
9. gt To specify the effective porosity Choose Effective Porosity from the Parameters menu Choose Matrix gt Reset from the Value menu or press Ctrl R and type 0 25 in the dialog box then click OK 3 Turn Layer Copy on by clicking the Layer Copy icon Al 4 Move to the second layer by pressing PgDn 5 Choose Leave Editor from the File menu or click the Leave Editor icon Ne The last step before performing the flow simulation of the sample model is to specify the location of the pumping well and 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 is 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 each layer The total pumping rate for the multilayer well is 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 T Q total ST 2 1 where T is the transmissivity of layer k and T is the sum of the transmissivities of all layers penetrated by the multilayer well As we do not know the required pumping rate for capturing the contaminated area shown
10. oR Data Format I10 INCEVT Enter the 6 data if FEVT T and INCEVT gt 0 6 Data CEVT NCOL NROW Input Module U2DREL Ts Data NSS Format I10 Enter the 8 data if NSS gt 0 8 Data KSS SS JSS CSS ITYPE Format LLQ 10 I10 F10 0 110 Explanation of Fields Used in Input Instructions FWEL FDRN FRCH FEVT FRIV FGHB MXSS INCRCH CRCH INCEVT CEVT is a logical flag for the Well option is a logical flag for the Drain option is a logical flag for the Recharge option is a logical flag for the Evapotranspiration option is a logical flag for the River option is a logical flag for General Head Dependent Boundary option If any of above options is used in the flow model its respective flag must be set to T otherwise set to F is the maximum number of all point sinks and sources simulated in the flow model Point sinks and sources include constant head cells wells drains rivers and general head dependent boundary cells Recharge and Evapotranspiration are treated as areally distributed sinks and sources thus they should not be counted as point sinks and sources MXSS should be set close to the actual number of total point sinks and sources in the flow model in order to minimize the computer memory allocated to store sinks and sources is a flag indicating whether an array containing the concentration of recharge flux will be read for the current stress period If INCRC
11. 1 h d d h d d for head save E H H t D D G H H for drawdown save all layers are treated the same way cell by cell flow terms cell by cell flow terms is not printed for t is printed for the corresponding layer for drawdown printout drawdown is not printed for the corresponding layer drawdown is printed for t Processing Modflow Input to Output is zero no output control head and total budget are ISTRT is not If IUNIT 12 if initial heads are saved unit 6 as specified in the main program If depending on the value of INCODE This means that than will fit on one line additional lines row This format is called the wrap format he printout is broken into strips where only across one line are printed in a strip As This format 3 ESEE E OFS 0 8 20F5 1 12 10G11 4 TSF 7 2 4 Bom C20F 52 1 be written if they are saved on disk the unit number to which drawdowns will be written if they are saved on disk determines the number of records in the 3 layer by layer specifications from the last time steps are used The The 3 data will consist of one data will consist of one record for each layer neither heads nor drawdowns will be printed or saved on disk heads and drawdowns will be printed or saved according to the flags data overall volumetric budget will not be printed overall volumetric budget will be printed hat the overall vo
12. DCEPS NPLANE NPL NPH NPMIN NPMAX SRMULT at F10 0 110 110 110 I10 110 F10 0 he 4 Data if MIXELM 2 or 3 INTERP NLSINK NPSINK at 110 I10 I10 he 5 Data if MIXELM 3 DCHMOC at F10 0 Explanation of Fields Used in Input Instructions MIXELM PERCEL MXPART ITRACK WD DCEPS NPLANE NPL is a flag indicating the advection solution scheme If MIXELM 1 the Method Of Characteristics MOC is used If MIXELM 2 the Modified Method Of Characteristics MMOC is used If MIXELM 3 the Hybrid MOC MMOC HMOC is used If MIXELM 0 the upstream finite difference method is used is the Courant number or number of cells any particle will be allowed to move in any direction in one transport step PERCEL is used to calculate the maximum allowed stepsize for particle tracking This stepsize is then compared with other stability criteria if any to determine an appropriate stepsize to be used in the simulation Generally 0 5 lt PERCEL lt 1 However values in excess of 1 can be used if the higher order particle tracking method is used throughout the grid Furthermore because all cells in the entire grid are checked when calculating the maximum allowed stepsize for particle tracking there may be a few cells where a particle will move more than one cell s length with PERCEL gt 1 while a particle will only move a fraction of a cell elsewhere If these cells are outside the area of interest setting PERCEL gt 1
13. a ps SS oO 3 Qe Plan View 5 1 60536 Cell Himengions 500 feet by 00 fe S560 636 x Fig 5 15 Configuration of the hypothetical model after McDonald et al 1991 Determination of the wetting threshold THRESH see equation 3 24 often requires considerable effort The user may have to make multiple test runs trying different values in different areas of the model On the right side of the model THRESH is negative in order to cause a cell to become wet only when the head in the layer below exceeds the wetting threshold This was done to avoid Applications and Sample Problems 5 16 Processing Modflow incorrectly converting dry cells to wet because of the large head differences between adjacent horizontal cells For example the simulation of natural conditions Stress Period 1 shows cells in column 14 of layer 1 being dry which is reasonable based on the head below these cells That is the head in column 14 of layer 2 is over 20 feet below the bottom of layer 1 However the head in column 13 of layer 1 is 21 feet above the bottom of the aquifer which means that if the head in adjacent horizontal cells is allowed to wet cells column 14 would convert to wet Thus it is not readily apparent whether column 14 should be wet or dry The trial simulations showed that when horizontal wetting is allowed column 14
14. Display Only Display Only Display Only Display Only Display Only Display Only ooo ojojo o ooo ojoo olco o ojoo Display Only Display Only oo gt Color Spectrum T Fig 2 19 The Search Level dialog box Your First Groundwater Flow Model with PMWIN 2 20 Processing Modflow File Value Options Help Res FES e sea 1 504 4586 377 3885 1 1 1 Steady state Recycle Fig 2 20 Solid fill plot and contour lines gt To calculate the capture zone of the pumping well 1 Choose Pathlines and Contours from the Run menu The Run PMPATH dialog box appears Fig 2 21 You can specify the full path and filename of the PMPATH program in the edit field or click LE to select the PMPATH program from a dialog box Normally you do not need to select the PMPATH program as PMWIN will set this automatically 2 In the Run PMPATH dialog box click OK PMWIN calls PMPATH by using the path and filename specified in the dialog box 3 In PMPATH click and select the model file SAMPLE MDL from the Open Model dialog box PMPATH loads the SAMPLE model and shows the model grid Fig 2 22 Note that if you have subsequently modified and calculated a model within PMWIN you must load the modified model into PMPATH again to ensure that the modifications can be recognized by PMPATH 4 To calculate the capture zone of the pumpin
15. MXSTRM NSS NTRIB NDIV ICALC CONST ISTCBl ISTCB2 Format I10 I10 I10 I10 I10 F10 0 110 110 FOR EACH STRESS PERIOD 23 Data ITMP IRDFLG IPTFLG Format I10 I10 I10 3 Data Layer Row Col Seg Reach Flow Stage Cond Sbot Stop Format I5 I5 I5 I5 I5 F15 0 F10 0 F10 0 F10 0 F10 0 The 3 data normally consists of one record for each reach Records are read in sequential order from upstream to downstream first by segments and then by reaches The downstream ordering and reading of segments and reaches are important as the order determines the connection of inflows and outflows If ITMP is negative or zero data 3 6 are not read If stream stages for each reach are to be calculated ICALC gt 0 then the following data set is read in sequential order of segment and reach 4 Data Width Slope Rough Format F10 0 F10 0 F10 0 If the maximum number of tributaries NTRIB that can join a segment is greater than zero then the following data set is read One record for each segment is read in sequential order A record is necessary even for segments that do not have tributaries In this case a blank record or a record with all zeros is read Ds Data Itrib 1 Itrib 2 Itrib NTRIB Format I5 I5 aaua DO If diversions are specified NDIV gt 0O then the following data set is read One record is read for each segment in sequential order For segments that are not diversions zeros or blanks are specified for each input item 6 Data Iupse
16. Report 88 729 Carson City Nevada 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 Saad Y 1985 Practical use of polynomial preconditionings for the conjugate gradient method SIAM Journal of Scientific and Statistical Computing 6 4 865 881 Scandrett 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 Shepard D 1968 A two dimensional interpolation function for irregularly spaced data Proceedings 23rd ACM National Conference 517 524 Stone H L 1968 Iterative solution of implicit approximations of multidimensional partial differential equations SIAM J Numer Anal 5 530 558 Trescott P C und S P Larson 1977 Comparison of iterative methods of solving two dimensional groundwater flow equations Water Resour Res 13 1 125 136 Wilson J L and P J Miller 1978 Two dimensional plume in uniform ground water flow J Hyd Div ASCE vol 4 503 514 Zheng C 1990 MT3D a modular three dimensional transport model S S Papadopulos amp Associates Inc Rockville Maryland Zheng C 1992 PATH3D A groundwater path and travel time simulator S
17. S Papadopulos amp Associates Inc Bethesda 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 References
18. Some of the sample problems are documented in the description of the corresponding software There is a model for each sample problem In order to give the user a complete reference these sample problems are described in this chapter again In the following sections the path to each model is given by Location An example which shows the input and output from MODFLOW see McDonald et al 1988 Appendix D is located in PMWIN EXAMPLES MFLOWEX 5 1 The Theis Solution Location PMWIN EXAMPLES THEIS Problem Description and Modeling Approach 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 This example gives an approximation of the Theis solution with a numerical model 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 potentiometric 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 with the numerical model The modeled
19. You can specify new value s in the dialog and click I to transfer the zone value s to the cells within the zone The zone value s has however nothing to do with the parameter estimation 6 Click the button The Parameter List dialog box appears Fig 3 33 7 Select a parameter a row from the Parameter Data table and change the appropriate settings in this row The zone is associated with this parameter row A parameter must be associated with a group defined in the Group Definition and Derivative Data table More than one zones can be associated with a parameter and more than one parameter can be associated with a group A parameter will only be estimated by PEST if the Active flag is set to YES You can switch the flag between YES and NO by clicking on the flag Click OK to accept the change 9 In the dialog box click OK to return to the Data Editor 2 The Modeling Environment Processing Modflow 3 53 Parameter Data Parameter List Prior Information __ Relative Relative Relative E Fig 3 33 The Parameter List dialog box The items of the Parameter List dialog box are described in details below gt Parameter Data Name is the parameter name given by PMWIN The parameter name of the first parameter is P1 The parameter name of the second parameter is P2 and so on The maximum number of paramters is 150 Active A parameter will only be estimated by
20. e v A 4 6c where AT t t For steady state flow fields the location of the particle at time t must be still within the cell 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 known the actual path of the particle within the cell The particle leaves the cell and enters a neighbouring cell This sequence is repeated until the particle reaches a discharge point or until a user specified time limit is reached The particle tracking is backward if all velocity terms in equation 4 3a 4 3f are multiplied by 1 For transient flow fields the simulation time is divided into stress periods time intervals during which all external stresses are constant which are in turn divided into time steps In addition to the condition for steady state flow fields t and t must lie within the same time step In PMPATH each particle is associated with a set of attributes i e the retardation factor the starting forward and backward travel times and positions If a particle is travelling across the end forward tracking or the beginning backward tracking of a time step of a flow simulation the modified algorithm sets t to this time and forces the particle to wait until the flow field of the next time step forward tracking or the previous time step backward tracking is read If the end or beginning
21. fifth button on the Toolbar until the button becomes gt To draw a zone 1 Click the Assign Value icon You do not need to click the Assign Value icon if it is already pressed down 2 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 4 Repeat steps 2 and 3 until the zone is closed or press the right mouse button to abort gt To assign new value s to a zone 1 Click the Assign Value icon You do not need to click the Assign Value icon if it is already pressed down 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 Statusbar 3 Press the right mouse button once The Data Editor shows a dialog box 4 In the dialog box type new value s then click E to transfer the new zone value s to cells PMWIN always uses the cell data and if zone data are not transferred default values within the cells are used by all other parts of the program except the parameter optimizing program PEST PEST uses the zonation information provided by the zones and the Parameter List See Chapter 5 for how to use the Parameter List and how to perform model calibrations with PEST You can shift a vertex of a zone by pointing the mouse cursor to the vertex node holding down the left mouse button while moving the mouse If you have many zones some zones can be cross
22. gt To specify the elevation of the top of model layers 1 Choose Top of Layers TOP from the Grid menu PMWIN shows the model grid 2 Choose Matrix gt Reset from the Value menu or press Ctrl R A Reset Matrix dialog box will come up 3 Type 10 in the dialog box then click OK The elevation of the top of the first layer is set to 10 4 Move to the second layer by pressing PgDn 5 Repeat steps 2 and 3 to set the top of the second layer to 3 6 Choose Leave Editor from the File menu or click the Leave Editor icon gt To specify the elevation of the bottom of model layers 1 Choose Bottom of Layers BOT from the Grid menu Your First Groundwater Flow Model with PMWIN Processing Modflow 2 7 2 3 Repeat the same procedure as described above to set the bottom of the first layer to 3 and the bottom of the second layer to 8 Choose Leave Editor from the File menu or click the Leave Editor icon Now we are going to specify the temporal and spatial parameters of the model For the sample problem spatial parameters include the starting hydraulic head horizontal and vertical hydraulic conductivities and effective porosity gt 1 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
23. is set If IGHBCB 0 cell by cell flow terms will not be printed or recorded If IGHBCB lt 0 boundary leakage for each cell will be printed whenever ICBCFL is set is a flag and a counter If ITMP lt 0 GHB data from the preceding stress period will be reused If ITMP gt 0 ITMP is the number of general head boundaries during the current stress period is the layer number of the cell affected by the head dependent boundary is the row number of the cell affected by the head dependent boundary is the column number of the cell affected by the head dependent boundary is the head on the boundary is the hydraulic conductance of the interface between the aquifer cell and the boundary Appendix A 22 Processing Modflow Recharge Package Input to the Recharge Package RCH1 is read from the unit specified in IUNIT 8 FOR EACH SIMULATION nS Data NRCHOP IRCHCB Format 110 110 FOR EACH STRESS PERIOD 23 Data INRECH INIRCH Format I10 110 3 Data RECH NCOL NROW Input Module U2DREL IF NRCHOP 2 4 Data IRCH NCOL NROW Input Module U2DINT Explanation of Fields Used in Input Instructions NRCHOP is the recharge option code Recharge fluxes are defined in a two dimensional array RECH with one value for each vertical column Accordingly recharge is applied to one cell in each vertical column and the option code determines which cell in the column is selected for recharge NRCHOP 1 Recharge is only to the top gri
24. k 2 293E 03 1 008E 03 1 100E 01 44531 1 3293E 01 2 8980E 05 5 9360E 09 J 4 4 09 55 09 X J K cross section number of particles current time step current stress period vertical velocity at the cell J 1 K horizontal velocity at the cell J K head at the cell J 1 K current cursor position in cell indices J K current cursor position in x y z coordinates Fig 4 6 The PMPATH modeling environment Modeling Tools 4 8 Processing Modflow Vy2 exit points of particles 1 and 2 7 Starting point of particle 2 V1 Vx2 0 VaV 0 Starting point of particle 1 y1 y2 hy Fig 4 7 Schematic illustration of the spurious intersection of two pathlines in a two dimensional cell gt Toolbar The Toolbar provides quick access to commonly used commands in the PMPATH modeling environment You click an icon on the toolbar once to carry out the action represented by that icon To change the current layer or the vertical local coordinate click the corresponding edit field in the Toolbar and type the new value then press ENTER See section 4 1 1 for the definition of the vertical local coordinate The following table summarizes the use of the Toolbar buttons of PMPATH Toolbar Button Action E 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
25. 04 1 57381E 04 2 57363E 04 4 55966E 5 59864E 1 10181E 03 3 76624E 04 3 99858E 04 6 97514E 04 3 81023E 4 5 77998E 04 1 14111E 03 1 28299E 03 7 5151E 04 1 35955E 03 8 29091E 04 6 90295E 04 03199E 04 1 26169E 9 06988E 8 91863E 04 0010087 1 02246E 03 7 45047E 04 3 23402E 1 36072E 03 8 09579E 04 3 5184E 04 5 2798E 04 4 80466E 4 09068E 04 4 21967E 04 4 4923E 04 Fig 3 38 The Browse Matrix dialog box gt To load an ASCII Matrix file 1 Click the Load button A Load Matrix dialog box appears Fig 3 39 2 Click and select an ASCII Matrix file from the standard open file dialog box 3 Specify the starting position As shown in Fig 3 40 the starting position gives the column and row at which an ASCII Matrix will be loaded The numbers of rows and columns of the ASCII matrix need not to be identical as those of the finite difference grid This allows you to replace only a 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 statistical parameters and load it into the grid 4 Select an option from the Options group Just before a loaded matrix is sent to the spreadsheet there are some possibilities to modifiy its values Replace Add Subtract Multiply Divide Processing Modflow The cell data in the spreadsheet
26. 10 Q A N l l A o oe hydraulic head m go l N Change in effective stress m o 360 720 1080 1440 1800 Simulation Time days Fig 5 28 Change in effective stress caused by a non declining cyclical ramp load Simulation Results The problem can be solved by simulating compaction in one half of a single doubly draining bed and multiplying those results by 200 to obtain the total compaction for all 100 interbeds To apply the IBS1 Package to this problem one approach would be to discretize the compressible bed into Applications and Sample Problems 5 32 Processing Modflow a number of model layers The problem could also be solved with a single row of finite difference cells in one model layer because flow in the low permeable compressible beds is assumed to be one dimensional The single row approach is less difficult than the multiple layer approach because input to and output from the flow model generally are carried out layer by layer A disadvantage of orienting the grid along a row is that the IBS1 Package sums compaction in all layers to compute total compaction The package is incapable of summing compaction along a row to calculate total compaction however the total compaction can be obtained by dividing the net cumulative volume of water released from interbed storage by the cross sectional area of the grid As shown in Fig 5 29 a cross sectional area of 1 m by 1 m was chosen so that
27. 4 075965E 05 3 821158E 05 6 510006E 05 4 06365E 05 3 723218E 05 Time Layer Layer Stress Period rh fi 1 Time Step Save Format ASCII Matrix Surfer Data File Result Type Concentration 4 809007E 02 4 628633E 02 4 388367E 02 5 780726E 02 5 635745E 02 5 456321E 02 6 792369E 02 6 696413E 02 6 553254E 02 Column Width 14 7 785328E 02 7 686552E 02 4 129644E 02 5 224279E 02 6 357138E 02 7 516653E 02 3 864779E 02 4 997296E 02 6 118661E 02 7 273538E 02 3 627735E 02 4 733118E 02 5 862047E 02 6 965069E 02 3 438641E 02 4 499775E 02 5 564398E 02 6 672165E 02 3 301356E 02 4 286475E 02 5 278913E 02 6 257062E 02 3 189698E 02 4 096115E 02 4 994368E 02 5 894772E 02 3 08981 3E 02 3 895154E 02 0471467 5 548922E 02 2 977026E 02 3 700705E 02 4 448099E 02 5 151314E 02 2 861979E 02 2 751162E 02 3 506532E 02 3 315651E 02 4 168234E 02 3 859163E 02 4 752367E 02 4 313505E 02 2 628482E 02 3 137115E 02 0363545 3 983655E 02 2 513766E 02 0298026 3 407381E 02 Time Layer Layer Total Elapsed Time 1 3 724185E 02 Save Format ASCII Matrix Surfer Data File 50 150 Fig 4 21 Reading the calculated concentration with the Results Extractor Modeling Tools 4 30 Processin
28. Assign Value Allows you to move the grid cursor and assign values a g Zoom In Allows you to drag a zoom window over a part of the model domain Zoom Out Forces the Grid Editor to display the entire worksheet Cell By Cell Input Method is activated Zone Input Method is activated Local Display Mode is activated Global Display Mode is activated Baa cee 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 if the small box on the lower left corner of this icon is highlighted Layer Copy On Off If you turn Layer Copy on and then move to an other layer the zones and cell values of the current layer will be copied Layer Copy is on if the small box on the lower left corner of this icon is highlighted The Modeling Environment 3 8 Processing Modflow 3 3 PMWIN Menus PMWIN contains the menus File Grid Parameters Packages Source Estimation Run Value Options and Help The Value and Options menus appear only in the Grid Editor and Data Editor The following table gives an overview of the menus in PMWIN Menu Usage File Create new models Open existing models Save plots Grid Generate or modify a model grid Input of the geometry of the grid Parameters Input of temporal and spatial model parameters such as transmissivity Packages Add specific features of hydrologic system into the groundwater model suc
29. Horizontal tydraulic Cdpductivity L T 0004 mouse cursor current data parameter or package period number if the current data is time depende position of the grid cursor in cell indices J I K parameter name if the Zone Input Method is used position of the mouse cursor in x y coordinates value of the cell J I K Fig 3 4 The Data Editor Local Display mode Processing Modflow EXAMPLE MDL File Value Options Help HERR ie kT N 1585 987 3713 376 47 401 fime independent Horizontal Hydraulic Conductivity L T 0004 Fig 3 5 The Global Display mode of the Data Editor The Modeling Environment 3 6 Processing Modflow Search and Modify Cell Values Search and Modify Cell Values Parameter Parameter Drain Hydraulic Conductance a Drain Hydraulic Conductance Drain Hydraulic Conductance Value 00005 Drain Elevation Search Range Options Search Range Options ox ae Replace Fee Replace Min 00005 Min 00005 C Add Multiply DE 00005 O Multiply Ee C Display Only E SNU Fig 3 6 Search and modify cell values The Zone Input Method The Zone Input Method allows you to assign parameters in the form of zones The zonation information will also be used by the parameter estimation program PEST To activate this method choose Input Method gt Zones from the Options menu Alternatively you can click the
30. It is suggested to 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 To assign the boundary condition to the flow model 1 Choose Boundary Condition IBOUND Modflow from the Grid Menu PMWIN shows the top view of the model grid Fig 2 6 The grid cursor is located in the cell 1 1 1 that is the upper left cell of the first layer The value of the current cell is shown at the bottom of the status bar The default value of the IBOUND array is 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 you can use PgUp or PgDn keys or click the edit field in the tool bar type the new layer number and then press enter 2 Pressing the right mouse button PMWIN shows a Cell Value dialog box 3 Type 1 in the dialog box then click OK The upper left cell of the model has been specified as a constant head cell 4 Now turn Duplication on by clicking the Duplication icon Es The small box on the lower right corner of this icon will be highlighted 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 Duplication off by clicking the Duplication icon again 5 Move the grid cursor from the upper left cell 1 1 1 to the lowe
31. Note that New particles will have the retardation factor specified in the Particle Placement dialog box Once particles are placed their color and retardation factor cannot be changed any more Modeling Tools 4 10 Processing Modflow Particle Placement Particles on cell faces Particles within cells OK Oa Face 1 NI x NK CER a al Face 2 NI x NK Face 3 NJ x NK i C _2 Face 4 NJ x NK 9 l o Face 5 NI x NJ Face 6 NI x NJ New Particles Color Retardation factor ooo fe Fig 4 8 The Particle Placement dialog box The retardation factor R is defined by Refi b k 4 8 where p is the bulk mass density of the porous medium n is the 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 can 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 particle velocity The velocity vectors in equation 3a 3f become Va Q nAy AzZ R Vio Ql Ay A2 R nes V Q 9 AxAz R 4 9c V2 Qyol mAxAz R 4 9d V Q nAxAy R 4 9e Vio QI nAxAy R al X Erase particle You can on
32. PEST if the Active flag is set to YES You can switch the flag between YES and NO by clicking on the flag Description is a place for you to take notes A Maximum of 120 characters is allowed PARVALI is a parameter s initial value For a fixed parameter this value remains invariant during the optimisation process For a tied parameter the ratio of PARVALI to the parent parameter s PARVALI sets the ratio between these two parameters to be maintained throughout the optimisation process For an adjustable parameter PARVALI is the parameter s starting value which together with the starting values of all other adjustable parameters is successively improved during the optimisation process To enhance optimisation efficiency you should choose an initial parameter value which is close to what you think will be the parameter s optimised value However you should note the following repercussions of choosing an initial parameter value of zero 1 A parameter cannot be subject to change limits see the discussion on RELPARMAX and FACPARMAX during the first optimisation iteration if its value at the start of that iteration is zero Furthermore FACORIG cannot be used to modify the action of RELPARMAX and FACPARMAX for a particular parameter throughout the optimisation 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 z
33. PMPATH uses the cell by cell flow terms and calculated hydraulic heads for calculating and displaying pathlines In addition to the Water Budget Calculator and PMPATH PMWIN provides various possibilities for checking simulation results and creating graphical output Using the Results Extractor simulation results of any layer and time step can be read from the unformatted binary result files and saved in ASCII Matrix files An ASCII Matrix file contains a value for each model cell in a layer The format of the ASCII Matrix file is described in Appendix 2 PMWIN can generate contour maps based on an ASCII Matrix file In the following we will accomplish the steps 1 Use the Water Budget Calculator to compute water budgets of each layer and the entire model and check if the percent discrepancies of in and outflows are acceptable small 2 Use the Result Extractor to read and save the calculated hydraulic heads of each layer 3 Generate contour maps based on the calculated hydraulic heads saved in step 2 4 Create a solid fill plot based on the calculated hydraulic heads saved in step 2 and add contours to the plot 5 Use PMPATH to produce pathlines as well as the capture zone of the pumping well gt To calculate subregional water budgets 1 Choose Water Budget from the Run menu A Water Budget dialog box will come up Fig 2 9 For a steady state flow simulation you do not need to change the settings in the Time group 2 Click Zo
34. SSOR Is read from the unit specified in IUNIT 11 FOR EACH SIMULATION 13 Data MXITER Format I10 Zu Data ACCL HCLOSE IPRSOR Format F10 0 F10 0 I10 Explanation of Fields Used in Input Instructions MXITER is the maximum number of iterations allowed in a time step ACCL is the acceleration parameter usually between 1 0 and 2 0 HCLOSE is the head change criterion for convergence When the maximum absolute value of head change from all nodes during an iteration is less than or equal to HCLOSE iteration stops IPRSOR is the printout interval for SSOR IF IPRSOR is equal to zero it is changed to 999 The maximum head change positive or negative is printed 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 Appendix Processing Modflow A 25 Preconditioned Conjugate Gradient 2 Package Input for the Preconditioned Conjugate Gradient 2 Package PCG2 is read from the unit specified in IUNIT 13 FOR EACH SIMULATION 1 Data MXITER ITER1 NPCOND Format I10 I10 I10 2 Data HCLOSE RCLOSE RELAX NBPOL IPRPCG MUTPCG IPCGCD Format F10 0 F10 0 F10 0 110 I10 I10 I10 Explanation of Fields Used in Input Instructions MXITER ITER1 NPCOND HCLOSE RCLOSE RELAX NBPOL IPRPCG MUTPCG IPCGCD is the maximum number of outer iterations that is calls to the solution routine For
35. Storage IBS1 Preconsolidation Head L Elastic Storage Factor Cancel 0001 Inelastic Storage Factor 001 Starting Compaction L 0 Current Column 7 Current Row 5 Fig 3 18 The Interbed Storage IBS1 dialog box The Modeling Environment 3 26 Processing Modflow For a confined aquifer elastic compaction or expansion of sediments is proportional or nearly proportional to change in hydraulic head in the aquifer The IBS1 Package uses the following equation to calculate the change in thickness Ab Ah S5 b Ah S 3 18 where Ab L is change in thickness positive for compaction and negative for expansion A A L is change in hydraulic head positive for increase S L is the skeletal component of elastic specific storage b 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 stress preconsolidation stress compaction is permanent inelastic In analogy to equation 3 18 the IBS1 package uses the following equation to calculate the approximate inelastic compaction Ab L Ab ARS oy be Ah Soa 3 19 where S L is the skeletal component of inelastic specific storage and S is the user specified inelastic storage factor For an unconfined aquifer elastic compaction or expansion of sediments can be expressed as Ab Ah 1 ntny Sosb Ah S 3 20 whe
36. XXX XXX XXX XXX XXX XXX 6 Data LAYCON NLAY Format 4012 Fs Data DELR NCOL Input Module U1DREL 8 Data DELC NROW Input Module U1DREL 9 Data HTOP NCOL NROW Input Module U2DREL 0 Data DZ NCOL NROW Input Module U2DREL one array for each layer 1 Data PRSITY NCOL NROW Input Module U2DREL one array for each layer 2 Data CBUND NCOL NROW Input Module U1DREL one array for each layer 3 Data SCONC NCOL NROW Input Module U2DREL one array for each layer 4 Data CINACT Format F10 0 5 Data FMTCN IFMTNP IFMTRF IFMTDP SAVUCN Format 0 110 110 I10 L10 6 Data NPRS Format 0 Entar the 17 Data only if NPRS gt 0 7 Data TIMPRS NPRS Format 8F10 0 8 Data NOBS Format 0 Enter the 19 Data NOBS times if NOBS gt 0 9 Data OBS IOBS JOBS Format 0 110 I10 20 Data CHKMAS Format L10 FOR EACH STRESS PERIOD 21 Data PERLEN NSTP TSMULT Format F10 0 I10 F10 0 Enter the 22 Data if TSMULT lt 0 22 Data TSLNGH NSTP Format 8F10 0 23 Data DTO MXSTRN Format F10 0 110 Explanation of Fields Used in Input Instructions HEADNG1 is the first line of any title or heading for the simulation run The line should not be longer than 80 characters HEADNG2 is the second line of any title or heading for the simulation run The line should not be longer than 80 characters NLAY is the total number of layers NROW is the total number of rows NCOL is the total number of columns NPER is th
37. a fraction of a cell elsewhere If these cells are outside the area of interest setting PERCEL gt 1 will not result in inaccuracy Note that if the upstream finite difference method for solving advection is used PERCEL must not exceed 1 gt WD is a concentration weighting factor between 0 and 1 The value of 0 5 is normally a good 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 small relative concentration gradient DCCELL such as 10 which is considered to be negligible gt NPLANE is a flag indicating whether the random or fixed pattern is selected for initial placement of moving particles If 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 22a This fixed pattern works well in relatively uniform flow Fields For two dimensional simulations in plan view set NPLANE 1 For cross sectional or three dimensional simulations The Modeling Environment 3 32 Processing Modflow NPLANE 2 is normally adequate Increase NPLANE if more resolution in the vertical direction is desired If NPLANE O the random pattern is selected for initial placement particles are distributed randomly by calling a random number generator in both the horizontal and vertical directions Fig 3 22b This
38. allows you to specify the iteration interval for attempting to wet cells WETIT Wetting is attempted every WETIT iterations If using the PCG2 solver Hill 1990 this applies to outer iterations not inner iterations The reason of adjusting WETIT is that the wetting of cells sometimes produces erroneous head changes in neighboring cells during the succeeding iteration which would 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 WETIT 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 WETIT 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 sam
39. and a number greater than zero in diverging converging flow fields Generally 0 lt NPMIN lt 4 is adequate gt NPMAX is the maximum number of particles allowed per cell If the number of particles in a cell exceeds NPMAX particles are removed from that cell until NPMAX is met Generally NPMAX can be set to a value approximately twice the value of 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 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 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 DCCELL gt DCHMOC The MMOC solution is selected at cells where DCCELL lt DCHMOC DCHMOC is only required when HMOC is used The Modeling Environment Processing Modflow 3 33 a Plane 1 Plane 2 Fig 3 22 Initial placement of moving particles after Zheng 1990 a Fixed pattern 8 particles are placed on two planes within the cell b
40. aquifer by any confining material 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 The infiltration of recharge to the aquifer is instantaneous no delay between the time precipitation infiltrates the surface until it reaches the water table 10 The discharge from the aquifer is only to the river Ae ees D ee ak columns 1 5 10 15 20 25 30 35 39 River Rows 13000 feet lt 8000 feet gt Fig 5 20 Configuration of the model and the location of the observation well Applications and Sample Problems 5 24 Processing Modflow 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 fully penetrating and the aquifer is 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 is assumed equal to the depth of the aquifer times the length of the river in each cell 1 000 ft divided by a
41. are replaced by those of the ASCII Matrix The cell values of the ASCII Matrix are added to those of the spreadsheet The cell data in the spreadsheet are subtracted from those of the loaded matrix The cell data in the spreadsheet are multiplied by those of the loaded matrix The cell data in the spreadsheet are divided by those of the loaded matrix If a cell data of the loaded matrix is equal to zero the corresponding cell data in the spreadsheet remains unchanged The Browse and Load Matrix dialog boxes provide you possibilities of manipulating your model data For example you can calculate the layer thickness by subtracting the bottom elevation from the top elevation The Modeling Environment Processing Modflow 3 63 File 4 pmwin examples pmextia_matrix dat Start Position gt Options Column J Row 1 Replace Add a a Maximum Numbers Multiply Column 57 Row 55 Divide Fig 3 39 The Load Matrix dialog box Starting position ASCII Matri Finite difference Grid Fig 3 40 The starting position of a loaded ASCII matrix Zones The Zones menu allows you to save or load the zones of the current layer in or from a Zone file Using Zone files you can transfer zonation information between parameters or between models with different grid configuration The format of th
42. by Cell Input Method To activate this method choose Input Method gt Cell By Cell from the Options menu You can alternatively click the fifth button on the Toolbar until the button becomes gt To assign new value s to a cell 1 Click the Assign Value icon You do not need to click the Assign Value icon if it is already pressed down 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 on the Statusbar 3 Press the right mouse button once The Data Editor shows a dialog box 4 In the dialog box type new value s then click OK If you double click a cell the Data Editor will highlight the cells that have the same value as the cell You can hold down the Ctrl key and press the left mouse button to open a Search and Modify Cell Values dialog box Fig 3 6 It allows you to display all cells that have a value located within the Search Range According to the user specified Value and the operation Options you can easily modify the cell values For example if Add is used the user specified value will be added to the cell value The Parameter drop down box contains the available parameter type s You choose a parameter for which the Search and Modify operation will apply The Modeling Environment Processing Modflow 3 5 current layer grid cursor File Value Options Help QJ 8c plies i 2291 636 1162 543 4421 Time independent
43. case the parameter takes only a limited role in the estimation process However the parameter to which the tied parameter is 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 The Modeling Environment Processing Modflow 3 55 PARCHGLIM is used to designate whether an adjustable parameter is relative limited or factor limited For tied or fixed parameters PARCHGLIM has no significance See the discussion on RELPARMAX and FACPARMAX PARGP is the number of the group to which a parameter belongs 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 MODFLOW it is multiplied by the real variable SCALE after which the real variable OFFSET is 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 conceal from PEST the true value of a par
44. 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 velocity components across each cell face are Vig Q 4 mAy Az 4 3a V2 Q o m Ay Az 4 3b Va Q 0 Ax Az 4 3c V2 Qy Ax Az 4 3d Va Q nAx Ay 4 3e Vo Q mAx Ay 4 3f where n is the effective porosity and Ven V Vr Yos Vey and Vv LT are the average velocity components across each cell face The semi analytical particle tracking algorithm uses simple linear interpolation to compute the principle velocity components at points within a cell Given the starting location x y 2 of the particle and the starting time t the velocity components are expressed in the form Modeling Tools 4 4 Processing Modflow V t A x Xx Va 4 4a V t AY V1 Va 4 4b VAG A Z 3 Va 4 4c where A A and A T are the components of the velocity gradient within the cell A V2 Vyq Ax 4 5a A V2 Vp 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 vy A 4 6a y t yi v t e vy LA 4 6b z t z v t
45. conductivities and thicknesses of layers to calculate VCONT if the corresponding Leakance flag in the Layer Options dialog is Calculated VCONT Av AVK4 3 3 Kijk Kiker where K jqand K ket are the vertical hydraulic conductivities of layers k and k 1 respectively Refer to Fig 3 1 1a for definition of Av and AVv 4 Equation 3 3 is used when each model layer represents a different hydrostratigraphic unit or when two or more model layers represent a single hydrostratigraphic unit a b Geohydrologic Upper layer UnitA A A 7 lij K 7 lik semiconfining unit AV i Azy 7 Geohydrologic 7 Pe Unit B y a Lower layer i Az E T T E E E ae a ae 7 ijKr y a AV k 1 y Az us ipK 1 Yo ge y y Fig 3 11 Grid configurations used for the calculation of VCONT The Modeling Environment 3 16 Processing Modflow For quasi three dimensional models that contain unsimulated semiconfining units VCONT must be specified by the user directly In this case VCONT can be calculated by using the following equation 2 Az 2AzZz Az 3 4 u c Ky K o K where K K o and K are the vertical hydraulic conditivities of the upper layer semiconfining unit and lower layer respectively Refer to Fig 3 11b for definition of AZ AZ and AZ You can specify VCONTby setting the corresponding Leakance flag in the Layer Options dialog box to User speci
46. domain presented in this model is therefore fairly large and a limited time frame is modeled An increasing grid spacing expansion is used to extend the model boundaries Fig 5 1 A single model layer is used to model the confined aquifer A fully penetrating well located at the center of the model domain pumps at a constant rate The drawdown of the head is monitored with time at an observation bore 55m from the pumping well The model parameters are listed below Starting hydraulic head 0 0 m Transmissivity 0 0023 m7 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 1 3 Number of SIP iteration paramters 5 Convergence criterion of head change 0 0001 Applications and Sample Problems 5 2 Processing Modflow Maximum number of iterations 50 pumping well observation poi Fig 5 1 Configuration of the groundwater model Simulation Results Both the analytical and calculated drawdown versus time curves are shown in Fig 5 2 The analytical values are specified in the Bores and Observations dialog box see section 3 3 6 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 tolerance and 4 artificial p
47. examples sample bcf dat Output Control e pmwin examples sample oc dat Well e pmwin examples sample wel dat Solver PCG2 e pmwin examples sample pcg2 dat Modpath Vers 1 x e pmwin examples sample main dat Modpath Vers 3 x e pmwin examples sample main30 dat Yes Yes Yes Yes Yes Yes Options l Regenerate all input files for MODFLOW F Check the geometrical setting up of the model Cancel l Generate input files only don t stat MODFLOW Help lt Fig 3 49 The Run Modflow dialog box gt The File Table PMWIN uses the user specified data to generate input files of MODFLOW and MODPATH The Description column gives the name of the packages used in the flow model The path and name of the input file are shown in the Destination column PMWIN generates an input file only if the The Modeling Environment 3 72 Processing Modflow Generate flag is set to YES You can click on a row to toggle the Generate flag between YES and NO Generally you do not need to worry about these flags as PMWIN will care about the settings See Appendix 3 for details about the input files of MODFLOW Note that you cannot run MODPATH and or MODPATH PLOT from PMWIN directly See Appendix 6 for how to run these programs gt Options e Regenerate all input files for MODFLOW You should check this option if the input files have been deleted or overwritten by ot
48. except that the lower aquifer discharges to a stream along the right side of the area Recharge from precipitation is 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 is pumped cells in the upper aquifer will desaturate Removal of the stresses will then cause the desaturated areas to resaturate Because horizontal flow in the confining bed is small compared to horizontal flow in the aquifers and storage is not a factor in steady state simulations the confining bed is not treated as a separate model layer The effect of the confining bed is incorporated in the value for vertical leakance see section 3 3 3 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 with MT3D A uniform horizontal grid of 10 rows and 15 columns is used Aquifer parameters are specified as shown in Fig 5 15 Simulation Results Two steady state solutions were obtained to simulate natural conditions and pumping conditions The two solutions are designed to demonstrate the abi
49. file label It must is the number of bores Max reserved A bore is active if Active is the x coordinate of the is the y coordinate of the Draw pore pore is the layer number of the If Draw 1 the obervation Viewer is activated is the color used to draw the obervation vs defined by a long integer using the equation vs 1 bore time curve of a bore will be shown when the Graphs time curve of a bore red green x 256 blue x A 3 see section 3 3 6 The color is 65536 where red green and blue are the color components ranging from 0 to 255 Appendix A 4 Observation File Processing Modflow An observation file can be created by the Bores and Observations dialog box see section 3 3 6 see section 4 6 An existing observation file can be imported into the Bores and Observations dialog box or the Graphs Viewer File Format I Data 2 Data The following Ss Data LABE NOBS BORE L FLAG XXX XXX XXX data repeats NOBS times NO TIME WEIGHT HEAD DDOWN CONC COMPAC PREHEAD SUBSDNS Explanation of Fields Used in Input Instructions ALL DATA IN TH LABEL NOBS FLAG XXX BORENO TIME WEIGHT HEAD DDOWN CONC COMPAC PREHEAD SUBSDNS Appendix is is if if is is is is is is is is is the the file label It must be PMWIN4000_OBS_FILE number of observations Maximum number of FLAG 1 the observed heads will be used for FLAG 2 the
50. in Fig 2 1 we will try a total pumping rate of 0 02 m s By applying equation 2 1 the pumping rates are 0 0185 m s and 0 0015 m s in the first and second layer respectively Your First Groundwater Flow Model with PMWIN Processing Modflow 2 9 gt To specify the pumping well and the pumping rate 1 Choose Well WEL1 from the Packages menu 2 Move the grid cursor to the cell 25 15 1 3 Press the right mouse button and type 0 0185 then click OK Negative value is used to indicate a pumping well 4 Move to the second layer by pressing PgDn 5 Press the right mouse button and type 0 0015 then click OK 6 Choose Leave Editor from the File menu or click the Leave Editor icon Perform the Flow Simulation Now everything is ready to run the flow simulation with MODFLOW gt To perform the flow simulation Select Run Menu and Choose Flow Computation Modflow A Run Modflow dialog box will appear Fig 2 7 2 Click OK to start the flow computation Prior to running MODFLOW PMWIN will use user specified data to generate input files of MODFLOW and 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 YES You can click on a row to toggle the Generate flag between YES and No Generally you do not need to change the Generate flags as PMWIN will care about the settings Run Modflow Modflow Version User s own zl Modflow Progr
51. is Relative and DERINC is 0 01 a suitable value in many cases the increment for each group member for each optimisation iteration is calculated as 0 01 times the current value of that member However if INCTYP is Absolute and DERINC is 0 01 the parameter increment is the same for all members of the group over all optimisation iterations being equal to 0 01 If INCTYP is Rel_to_max and DERINC is again 0 01 the increment for The Modeling Environment 3 56 Processing Modflow all group members is the same for any one optimisation iteration being equal to 0 01 times the absolute value of the group member of highest current magnitude however the increment may vary from iteration to iteration 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 is 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 parameter magnitudes e DERINCLB If a parameter increment is calculated as Relative or Rel_to_max it is possible that 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 lo
52. load H1 DAT into the model grid Skip these steps if the data were saved in the previous procedure 3 Choose Search and Modify from the Value menu The Search and Modify dialog box appears Fig 2 17 If a row of the table is active model cells with values located between the Minimum and Maximum will be filled with the user specified Color 4 Set the first 10 rows to active by clicking on cells of the Active column A row is active if Active is set to Yes 5 To assign colors to the active rows click Spectrum The Color Spectrum dialog box appears Fig 2 18 6 Inthe Color Spectrum dialog box click on the Minimum button and select a color Click on the Maximum button and select a color Click OK when finished 7 To set the search ranges click Level The Search Level dialog box appears Fig 2 19 8 Inthe Search Level dialog box type 8 and 9 in the Minimum and Maximum edit fields Click OK when ready 9 Inthe Search And Modify dialog box click OK PMWIN redraws the model and fills colors to cells You can overlay contours to the solid fill plot by doing the following 1 Choose Environment from the Options menu check the Visible check box then click OK 2 Choose Search and Modify from the Value menu then Click OK Fig 2 20 shows a solid fill plot with contour lines Your First Groundwater Flow Model with PMWIN Processing Modflow 2 19 Search And Modify Parameter Ignore Inactive Cells o Display Only
53. mean safety criterion converges Contaminated area pumping well Realization 1 Safety Criterion 87 5 Mean Safety Criterion 87 5 Realization 2 Safety Criterion 91 5 Mean Safety Criterion 89 5 Realization 3 Safety Criterion 100 Mean Safety Criterion 93 Realization 4 Safety Criterion 83 Mean Safety Criterion 90 5 Realization 5 Safety Criterion 100 Mean Safety Criterion 92 4 Fig 5 14 Calculation of the mean safety criterion by using the Monte Carlo method Applications and Sample Problems 5 14 Processing Modflow 5 6 Simulation of a Two Layer Aquifer System in which the Top Layer Converts Between Wet and Dry Location PMWIN EXAMPLES BCF2 EX1 Problem Description and Modeling Approach This example is from the first test problem of the BCF2 Package McDonald 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 This problem demonstrates the capability of the BCF2 Package to successfully simulate this common hydrologic situation which is difficult or impossible to simulate with the original BCF1 Package The model consists of two layers one for each aquifer separated by a confining unit Fig 5 15 No flow boundaries surround the system on all sides
54. not used to adjust limits for log transformed parameters FACORIG must be greater than zero A value of 0 001 is often suitable gt PHIREDSWH The derivatives of observations with respect to parameters can be calculated using either forward differences involving two parameter observation pairs or one of the variants of the central method involving three parameter observation pairs described in Section 2 3 1 of the manual of PEST As discussed below in Parameter List you must inform PEST through the group variables FORCEN and DERMTHD which method is to be used for the parameters belonging to each parameter group Using the variable FORCEN you may wish to decree that for a particular parameter group derivatives will first be calculated using the forward difference method and later when PEST is faltering in its attempts to reduce the objective function calculated using one of the central methods Alternatively you may direct that no such switching take place the forward or central method being used at all times for the parameters belonging to a particular group In the former The Modeling Environment 3 50 Processing Modflow case you must provide PEST with a means of judging when to make the switch this is the role of the real variable PHIREDSWH If the relative reduction in the objective function between successive optimisation iterations is less than PHIREDSWH PEST will make the switch to three point derivatives calculation for
55. number where streamflow out of each reach will be saved on disk whenever the variable ICBCFL is specified If ISTCB2 lt 0 streamflows out of each reach will not be saved on disk ITMP is a flag and a counter If ITMP lt 0 stream data from the last stress period will be reused If ITMP gt 0 ITMP will be the number of reaches active during the current stress period IRDFLG is a flag which when positive suppresses printing of the input data set specified for a stress period The input data set is printed for a stress period if the value is zero or blank Appendix Processing Modflow A 27 IPTFLG Layer Row Col Seg Reach Flow Stage Cond Sbot Stop width Slope Rough Teetb 2 Itrib 2 Iupseg is a flag which when positive suppresses printing of results for a stress period The results are printed for a stress period if the value is zero or blank and whenever the variable ICBCFL is specified is the layer number of the cell containing the stream reach is the row number of the cell containing the stream reach is the column number of the cell containing the stream reach is a number assigned to a group of reaches Segments must be numbered in downstream order and are read into the program in sequential order 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 Reaches must be read in sequentiall
56. observed drawdowns will be used reserved the he he he he he he he the chock chock chock ck bore number where the observation is made observation time measured from the start weight attached to each observation observed head at time TIME observed drawdown at time TIME observed concentration at time TIME compaction at time TIME preconsolidation head at time TIME subsidence at time TIME E SAME RECORD ARE SEPARATED BY A COMMA OR BLANK NOBS is 6000 the parameter estimation for the parameter estimation of the simulation Processing Modflow A 5 Time Parameter File A Time Parameter file can be saved or loaded by the Time Parameter dialog box see section 32323 File Format Le 2a The 3 Explanat ALL LABE NPER Data LABEL Data NPER ITMUNI following data repeats NPER times Data ACTIVE PERLEN NSTP TSMULT DTO MXSTRN ion of Fields Used in Input Instructions DATA IN THE SAME RECORD ARE SEPARATED BY A COMMA OR BLANK L is the file label It must be PMWIN4000_TIME_FILE 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 times
57. olsololololsolo elofolofolofolofolofolalololo slofolefolo ols o slofolofole olo olo BC t 1 Time Layer Layer Stress Period Time Step Save Format ASCII Matrix Surfer Data File ph Save Help Read Close Fig 2 11 Result types and the Results Extractor dialog box 10 To generate contour maps of the calculated heads Choose Recycle from the Parameters menu Data specified in Recycle will not be used by any simulation programs We can use Recycle to save temporary data or to display simulation results graphically Choose Matrix Browse from the Value menu or Press Ctrl B A Browse Matrix dialog box appears Fig 2 12 Each cell of the spreadsheet is corresponding to a model cell in the current layer You can load an ASCI Matrix file into the spreadsheet or save the spreadsheet in an ASCII Matrix file by clicking Load or Save Click Load A Load Matrix dialog box will appear Fig 2 13 Click and select the file H1 DAT which will be loaded H1 DAT is saved by using the Results Extractor Click OK when ready H1 DAT is loaded and put into the spreadsheet In the Browse Matrix dialog box click OK The Browse Matrix dialog box will be closed Choose Environment from the Options menu or Press Ctrl E An Environment Options dialog box appears Fig 2 14 It allows the user to modify the appearance and position of the model grid In the En
58. pmex field Parameter Characteristics Number of Realizations 1 to 999 2 Mean Value log10 30 to 30 2 Standard Deviation log10 30 to 30 5 Correlation Length Field Width in the I direction 0 to 1 1 Correlation Length Field Width in the J direction 0 to 1 1 Number of Cells in the direction 2 to 400 30 Number of Cells in the J direction 2 to 400 30 Fig 4 18 The Field Generator dialog box The simulation of the hydraulic conductivity distribution produced in this way is unconditional because the hydraulic conductivity values are not constrained to match point measurements in the real field In the conditional simulation existing measurements are used which reduce the space of possible realizations The conditional generation of a single realization procedes in five steps 1 The parameter value for each model cell are interpolated from the measurements using the Kriging method The correlation length is determined from the measurements Modeling Tools Processing Modflow 4 27 2 An unconditional generation is performed using the Field Generator with the same correlation 3 length correlation scale The unconditionally generated values at the measurement locations are used to interpolate values for each model cell by using the Kriging method again The distribution from step 3 is subtracted from the distribution from step 2 yielding kriging residuals The kriging
59. 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 Wat Res Res 17 1 250 253 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 no 16 37 pp Pollock D W 1988 Semianalytical computation of path lines for finite difference 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 References Processing Modflow 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
60. pumping well Through backward tracking capture zones of each pumping well can be recognized by their different colors Run particles backward Click the Run particles backward icon to execute backward particle tracking for a time length The time length is defined by the product of the number of particle tracking steps by the particle tracking step length given in the Particle Tracking Options dialog box See the section Particle Tracking Options for details Run particles backward step by step Click the Run particles backward step by step icon to move particles backward a single particle tracking step The particle tracking step length is defined in the Particle Tracking Options dialog box Stop You can click the Stop button to stop particle tracking or stop redrawing particles when the Stop button is highlighted the rectangle on the button is colored in red PMPATH redraws the particles whenever the PMPATH window has been covered by other windows and is activated again For example if you change to another application and then return Modeling Tools 4 12 Processing Modflow to PMPATH PMPATH will redraw all particles If too many particles are placed you will need to stop PMPATH redrawing all particles Under some circumstances PMPATH will take a long time for calculating the coordinates of flow paths and travel times This is especially true if the flow velocities and the user specified time step length of particle t
61. 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 Modeling Tools 4 28 Processing Modflow 4 4 The Results Extractor Normally simulation results from MODFLOW or MT3D are saved unformatted binary and cannot be viewed by using usual text editors Using the Results Extractor Fig 4 19 you can read the unformatted binary result files and save them in ASCII Matrix or Surfer Data files see Appendix 2 Results Extractor Result Type Column Width Hydraulic Head l 10 8 895605 8 860457 8 82521 8 789894 8 754512 4 8 895454 8 860298 8 825026 8 789684 8 754284 E 8 895316 8 860154 8 824866 8 789497 8 754069 i 8 895185 8 860009 8 824706 8 789311 8 753851 8 895058 8 859861 8 824537 8 789117 8 75362 8 894938 8 859712 8 824363 8 788911 8 753375 8 894823 8 859567 8 824185 8 788698 8 753119 8 894716 8 859426 i 8 788487 8 752863 8 894619 8 859297 8 823849 8 788285 8 752614 8 894531 8 85918 8 8237 8 788099 8 752384 8 894456 8 859078 8 82357 8 787937 8 752183 8 894394 8 858995 8 823463 8 787805 8 752019 8 894348 8 858932 8 823384 8 787707 8 751898 8 89432 8 858894 i 8 787647 8 751826 8 894311 8 858881 i 8 787629 8 751807 Save Format ASCII Matrix Surfer Data File Time Layer Layer Stress Period Time Step 1 fi
62. rivers drains head dependent boundaries recharge and evapotranspiration PMWIN also supports the calculation of elastic and inelastic compaction of an aquifer due to changes of hydraulic heads The particle tracking model PMPATH for Windows is included in PMWIN 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 shows pathlines or flowlines and travel time marks simultaneously It provides various on screen graphical options including head contours drawdown contours and velocity vectors The development of the particle tracking model MODPATH can be roughly divided into two stages The earlier release of MODPATH was developed to compute flowlines based on output from steady state flow simulations by MODFLOW The most recent release of MODPATH permits forward and backward tracking in transient flow fields as well as steady state flow fields Output from MODPATH can be displayed graphically by using the program MODPATH PLOT 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
63. step in an attempt to solve the system of finite difference equations e IPRSIP is the printout interval for SIP 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 IPRSIP This printout also occurs at the end of each stress period regardless of the value of IPRSIP e NPARM is the number of iteration parameters to be used Five parameters are generally sufficient e ACCL is the acceleration parameter It must be greater than zero and is generally equal to one e Head Change 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 Strongly Implicit Procedure SIP Max Allowed Iteration Number MXITER 50 Printout From the Solver Help Interval IPRSIP 1 l l No of Iteration Parameters NPARM l Acceleration Parameter ACCL l Convergence Criterion Head Change L 001 Fig 3 26 The Strongly Implicit Procedure SIP dialog box The Modeling Environment Processing Modflow 3 39 gt SSOR You specify the required parameters in the Slice Successive Overrelaxation SSOR dialog box Fig 3 27 The parameters are described below e MXITER is the maximum number of iterations in one t
64. suppress all printout from the solver e Thecheck box Calculate the upper bound on the maximum eigenvalue is only used with POLCG The upper bound on the maximum eigenvalue of A is estimated as the largest sum of the absolute values of the components in any row of A Check this box if the upper bound should be calculated by the solver Otherwise a value of 2 will be used Convergence is generally insensitive to this value Estimation of the upper bound uses slightly more execution time per iteration Output Control The Output Control menu is used to control the frequency and terms of simulation results of MODFLOW and MT3D that will be printed or saved The available options are described below gt Modflow Different simulation results can be saved in files by checking the corresponding output terms in the Modflow Output Control dialog box Fig 3 29 The simulation results are saved whenever the time step and stress period are an even multiple of output frequency specified in the dialog Note that the results for the first and last stress periods and time steps are always saved Use 0 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 NDRY are given in the Predefined Head Values group The Modeling Environment Processing Modflow 3 41 The output terms and the corresponding result files are described below All r
65. the futility of further processing you should set this variable very high A value of 20 to 30 is often appropriate gt PHIREDSTP and NPHISTP PHIREDSTP is a real variable whereas NPHISTP is an integer variable If in the course of the parameter estimation process there have been NPHISTP optimisation iterations for which Co Pie 0 lt PHIREDSTP 3 47 Q being the objective function value at the end of the i th optimisation iteration and being the lowest objective function achieved to date PEST will consider that the optimisation process is at an end For many cases 0 01 and 3 are suitable values for PHIREDSTP and NPHISTP respectively However you must be careful not to set NPHISTP too low if the optimal values for some parameters are near or at their upper or lower bounds as defined by the parameter variables PARLBND and PARUBND discussed in Parameter List In this case it is possible that the The Modeling Environment Processing Modflow 3 51 magnitude of the parameter upgrade vector may be cut down over one or a number of optimisation iterations to ensure that no parameter value overshoots its bound The result may be smaller reductions in the objective function than would otherwise occur It would be a shame if these reduced reductions were mistaken for the onset of parameter convergence to the optimal set gt NPHINORED If PEST has failed to lower the objective function over NPHINORED successive iterat
66. the Field Generator with the settings shown in Fig 5 12 lognormal distributions of the horizontal hydraulic conductivity are generated and saved in ASCII 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 generated by using PMPATH The safety criterion can be quantified by using Monte Carlo simulations whereby many such realizations of the parameter field are produced and used in the flow simulation Field Generator Output Filename Without Extension le pmwin examples sample field Parameter Characteristics Number of Realizations 1 to 999 19 Mean Value log10 30 to 30 2 31 Standard Deviation log10 30 to 30 5 Correlation Length Field Width in the X direction 0 to 1 1 Correlation Length Field Width in the Y direction 0 to 1 1 Number of Cells in the X direction 2 to 400 30 Number of Cells in the Y direction 2 to 400 30 Fig 5 13 Use of the Field Generator to create lognormal correlated distributions of model parameters Applications and Sample Problems Processing Modflow 5 13 Fig 5 14 shows results of five realizations and the calculated mean safety criteria Mean safety criterion is the sum of safety criteria divided by the number of realizations A large number of realizations may be needed until the
67. the flow field significantly This allows the user to construct and calibrate a flow model independently After a flow simulation is complete MT3D retrieves the calculated hydraulic heads and various flow terms saved by MODFLOW The MT3D transport model 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 currently limited to equilibrium controlled linear or non linear sorption and first order irreversible decay or biodegradation The purpose of PEST which is an acronym for Parameter ESTimation is to assist in data Introduction 1 2 Processing Modflow interpretation and in model calibration If there are field or laboratory measurements PEST can adjust model parameters and or excitation data in order that the discrepancies between the pertinent model generated numbers and the corresponding measurements are reduced to a minimum It does 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 PMWIN helps the user to inform PEST of assigning the adjustable parameters and excitations New Features in PMWIN PMWIN is capable of using all available memory There is almost no limit to the model size PMWIN can handel models with up to 80 layers and 1000 stress periods Each mo
68. the layer in each vertical column where recharge is applied Recharge flux L T Layer indicator array that defines the layer in each vertical column where recharge is applied Hydraulic conductance of riverbed Elevation of the bottom of riverbed Water surface elevation of river Hydraulic conductance of riverbed Elevation of the bottom of riverbed Water surface elevation of river Elevation of the bottom of the streambed Segment number sequential number assigned to a group of reaches Streamflow in length cubed per time Sequential number of reaches Manning s roughness coefficient C for each stream reach Slope of the stream channel in each reach Stream stage Streambed hydraulic conductance Elevation of the top of the streambed Width of the stream channel in each reach Segment number sequential number assigned to a group of reaches Sequential number of reaches within a segment Streamflow in length cubed per time Stream stage Streambed hydraulic conductance Elevation of the top of the streambed Elevation of the bottom of the streambed Width of the stream channel in each reach Slope of the stream channel in each reach Manning s roughness coefficient C for each stream reach Volumetric recharge rate of wells Volumetric recharge rate of wells Appendix A 10 Packages continued Extension Description MT3D Sink amp Source Package TCH CBC Specified concentration TE
69. the row number of the cell affected by the specified head boundary is the column number of the cell affected by the specified head boundary is the head value at the cell at the start of the stress period Because the package assigns head values on the basis of linear interpolation to the end of a time step the assigned specified head value will never equal StartHead unless StartHead and EndHead are equal is the head value at the cell at the end of the stress period It is the value that will be assigned to the cell for the last time step in the stress period Appendix A 32 Processing Modflow Appendix 4 Input Instructions of MT3D These input instructions are intended as a reference for the experienced user PMWIN translates the user specified data to the input files of MT3D by using the rules given in these input instructions Most explanations of the input variables are contained in Chapter 3 of this manual or in Chapter 6 of the manual of MT3D Zheng 1990 Basic Transport Package Input to the Basic Transport Package BTN is read on unit 1 which is preset in the main program of MT3D Since the BTN Package is needed for every simulation this input file is always required FOR EACH SIMULATION Ts Data HEADNG1 Famat A80 Zi Data HEADNG2 Format A80 Bes Data NLAY NROW NCOL NPER Format 10 110 I10 I10 4 Data TUNIT LUNIT MUNIT Format A4 A4 A4 Os Data TRNOP 10 Format OL2 ADV DSP SSM RCT
70. the standard File Open dialog box 2 Ifnecessary use a scale factor to enlarge or reduce the appearance size of the DXF map Use the values in X and Y to shift the scaled DXF map to the desired position For details see Scaling a DXF map below 3 Click the color button in the front of the DXF file edit field and select a standard color for the DXF map from the Color dialog box A DXF graphics entity will have the standard color if the entity s color is not defined in the DXF file 4 Check the check box next to the DXF file edit field The map will be displayed only when the box is checked e Scaling a DXF map Normally X and Y should be 0 and Scale should be 1 if a DXF file is generated by PMWIN or PMPATH However some drawing or CAD software will store the coordinates in the DXF file in other units If the scale factor or the X Y values are incorrect a DXF map will be displayed too small too large or outside of the worksheet If this happens use the Environment options 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 the distance with the status bar If the distance is incorrect compute a scale factor and import the map again Once you have a correct scale factor you can shift the s
71. those parameter groups for which the character variable FORCEN has the value switch thus if for the i th iteration Ora mae lt PHIREDSWH 3 46 where is the objective function calculated on the basis of the upgraded parameter set determined in the i th iteration then PEST will use central derivatives in iteration i 1 and all succeeding iterations for all parameter groups for which FORCEN is switch A value of 0 1 is often suitable for PHIREDSWH If it is 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 to fill the Jacobian matrix than are really needed at that stage of the estimation process If PHIREDSWH is set too low PEST may waste an optimisation 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 the input variable PHIREDSTP which sets one of the termination criteria on the basis of the relative objective function reduction between optimisation iterations NOPTMAX NOPTMAX sets the maximum number of optimisation iterations that PEST is permitted to undertake on a particular parameter estimation run If you want to ensure that PEST termination is triggered by other criteria more indicative of parameter convergence to an optimal set or of
72. time of a flow simulation is reached the modified algorithm can treat the latest flow field as steady state and the movement of particles can go on gt 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 Fig 4 4 i e all model cells in the same layer have the same thickness In practice many modelers use variable layer thickness to simulate the varying thickness of stratigraphic geohydrologic units Fig 4 5 In order to calculate approximate groundwater paths for the last discretization type PMPATH as well as MODPATH uses a Modeling Tools Processing Modflow 4 5 vertical local coordinate instead of the Z coordinate The vertical local coordinate is defined for each cell as Z Z 2 2 4 7 where z and z are the elevations of the bottom and top of the cell respectively According to this equation the vertical local coordinate z equals O at the bottom of the cell and 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 beneat
73. to start the generation of the input files of MT3D In addition PMWIN generates a batch file MT3D BAT saved in your model directory After having generated all necessary files PMWIN automatically opens a DOS box and runs MT3D BAT in the box Follow the steps below if you want to run MT3D outside of Windows 1 2 3 4 In the Run MT3D dialog box check the option Generate input files only don t start MT3D then click OK Leave Windows Change the default path to your model directory Type MT3D BAT at the DOS prompt then press enter During a transport simulation MT3D writes a detailed run record to the file OUTPUT MT3 saved in your model directory The calculated concentrations are saved in the unformatted binary file MT3D UCN See Output Control for details The Modeling Environment Processing Modflow 4 1 4 Modeling Tools 4 1 The Advective Transport Model PMPATH PMPATH is an advective transport model running independently from PMWIN PMPATH retrieves the groundwater models created in PMWIN and simulation result files from the flow model MODFLOW A semi analytical particle tracking scheme Pollock 1988 1989 is used to calculate the groundwater paths and travel times Through the interactive graphical modeling environment of PMPATH the user 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
74. 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 e Evapotranspiration Similarly to Recharge evapotranspiration can be assigned to the top face of a cell or treated as a distributed sink Modeling Tools 4 16 Processing Modflow 4 1 4 PMPATH Output Files gt Plots To save the contents of the Top view window in plot files choose Save Plot As from the File menu and specify the format and the file name in the dialog box Fig 4 11 Four formats are available Drawing Interchange Format DXF Hewlett Packard Graphics Language HP GL Windows Bitmap BMP and the PATHLINE file of MODPATH To select a format click the down arrow on the Format drop down box You can type in the file name in the file edit field directly or click the right mouse button on the edit field and select a file from the standard File Open dialog box Note that PMPATH uses the same color resolution as the video screen to save Windows Bitmap files The True Color resolution is not supported by PMPATH Do not save plots in the Windows Bitmap format if you are using the True Color resolution Save Plot As a a x _ File c pm3 ex example dxf Click the right mouse button on the file fields to select a file Fig 4 11 The Save Plot As dialog box If the MODPATH format is chosen coordinates along the path of each particle are recorded in
75. will not result in inaccuracy Note that if MIXELM 0 i e using upstream finite difference method for solving advection PERCEL must not exceed 1 is the maximum number of total moving particles allowed and is used only when MIXELM 1 or 3 is a flag indicating which particle tracking algorithm is selected If ITRACK 1 the first order Euler algorithm is used If ITRACK 2 the fourth order Runge Kutta algorithm is used If ITRACK 3 the Runge Kutta algorithm is used in sink source cells and the cells next to sinks sources while the Euler algorithm is used elsewhere is a concentration weighting factor between 0 and 1 The value of 0 5 is normally a good choice This number can be adjusted to achieve better mass balance Generally it can be increased toward 1 as advection becomes more dominant is a small relative concentration gradient DCCELL which is considered to be negligible see equation 3 27 is a flag indicating whether the random or fixed pattern is selected for initial placement of moving particles If NPLANE 0 the the random pattern is selected for initial placement Particles are distributed randomly by calling a random number generator in both the honzontal and vertical directions refer to Fig 3 22b This option generally leads to smaller mass balance discrepancy in nonuniform or diverging converging flow fields If NPLANE gt 0 the fixed pattern is selected for initial placement The value of NPLANE serves
76. 0 i i 49 0 65 5 66 0 66 5 67 0 67 5 68 0 gt measurememt point ak Fig 5 7 Plan view of the model area Interpolation Results The interpolation results are shown in the form of contours in Fig 5 8 5 11 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 c 0 and a 1 For comparison the contours produced by SURFER are shown in Fig 5 12 where the inverse distance method and the octant search method with Data Per Sector and weighting exponent F 2 were used The grid size used in SURFER is 80x80 points The slight difference between Fig 5 8 and Fig 5 12 is caused by different numbers of columns and rows of the grid There is no significant difference observed in these figures when sufficient data points are available The major difference is observed in the southern part of the model area where only one measurement point is found and the system is not well conditioned Applications and Sample Problems Processing Modflow 5 9 65 5 68 0 515 515 51 0 51 0 50 5 7150 5 50 0 50 0 49 5 149 5 49 ol i 49 0 66 0 66 5 67 0 675 68 0 2 measurement point e a Fig 5 8 Contours produced by Shepard s inverse distance method
77. 00 Elapsed Simulation Time days Fig 5 27 Calculated compaction at the observation point 1 Applications and Sample Problems Processing Modflow 5 31 5 12 Simulation of a Non declining Cyclical Ramp Load Problem Location PAWIN EXAMPLES IBS 1 EX2 Problem Description and Modeling Approach This example is from the second test problem of the Interbed Storage IBS1 Package Leake and Prudic 1991 The ramp load problem presented here is similar to the non declining ramp load problem given by Helm 1975 p 470 473 Helm computes compaction of compressible beds given effective stress changes at the boundary by solving a one dimensional partial differential equation by finite differences This example involves the simulation of the cumulative compaction of 100 identical interbeds with the following properties Thickness 10 m Hydraulic conductivity 2 78x10 m d Elastic specific storage 1x10 1 m Inelastic specific storage 1x104 1 m The head at the boundaries of the interbeds is set to successively decline linearly for 180 days to 10 m below the starting value Following the declines the head recovers linearly for 180 days to the original value Successive cycles of declines and recoveries are approximated with 180 1 day steps in each ramp Fig 5 28 The preconsolidation head throughout the interbeds is assumed to be equal to the starting head so that compaction is initially in the inelastic range
78. 1 21 Reserved 22 LKMT Package this package creates interface files to MT3D 23 Block Centered Flow Package 3 BCF3 Not Supported by PMWIN 24 Block Centered Flow Package 1 BCF1 Not Supported by PMWIN as BCF2 has all options of BCF1 indicates whether array BUFF is separate from array RHS f IAPART O0 Default by PMWIN the arrays BUFF and RHS occupy the same space This option conserves space This option should be used unless some other package explicitly says otherwise f IAPART 0 the arrays BUFF and RHS occupy different space indicates whether initial heads are to be saved If they are saved they will be stored in array STRT They must be saved if drawdown is calculated f ISTRT 0 initial heads are not saved f ISTRT O Default by PMWIN initial heads are saved is the boundary array f IBOUND I J K lt 0 cell I J K has a constant head f IBOUND I J K 0 cell I J K is inactive no flow f IBOUND I J K gt 0 cell I J K is variable head is the value of head to be assigned to all inactive cells IBOUND 0 throughout the simulation Since heads at inactive cells are unused this does not affect model results but serves to identify inactive cells when head is printed This value is also used as drawdown at inactive cells if the drawdown option is used Even if the user does not anticipate having inactive cells a value for HNOFLO must be submitted is head at the start of the simulation Regardless of wheth
79. 1 Fig 4 19 The Results Extractor a box The result files include hydraulic head drawdown cell by cell flow terms preconsolidation head compaction subsidence and concentraion see Output Control of section 3 3 4 for the definition of each term You can choose a result type from the Result Type drop down dox The spreadsheet displays a series of columns and rows which are corresponding to the columns and rows of the finite difference grid By clicking the Read button a result will be read and put into the spreadsheet In the Time Layer group you specify the layer number stress period and time step from which the result is read If the result type is Cell By Cell Flow Terms you can select a flow term the Flow Term drop down dialog box Fig 4 20 Refer to section 4 5 for the definition of the flow terms If the result type is concentration you can choose a total elapsed time at which calculated concentration is saved Fig 4 21 By setting a Save Format and clicking the Save button the result can be saved Modeling Tools Processing Modflow 4 29 Results Extractor Result Type Flow Term Column Width Cell By Cell Flow Terms 5 110249E 05 3 669192E 05 4 678602E 05 1 767147E 05 3 706648E 05 4 384415E 05 3 428539E 05 3 834661E 05 4 18024E 05 5 037387E 05 3 971086E 05 4 033763E 05 5 106714E 05 4 045864E 05 3 92024E 05 5 582141E 05
80. 10 0 110 F10 0 110 Explanation of Fields Used in Input Instructions MXITER is the maximum number of times through the iteration loop in one time step in an attempt to solve the system of finite difference equations Fifty Iterations are generally sufficient NPARM is the number of iteration parameters to be used Five parameters are generally sufficient ACCL is the acceleration parameter It must be greater than zero and is generally equal to one If a zero is entered it is changed to one HCLOSE is the head change criterion for convergence When the maximum absolute value of head change from all nodes during an iteration is less than or equal to HCLOSE iteration stops IPCALC is a flag indicating where the iteration parameter seed will come from 0 the seed will be entered by the user 1 the seed will be calculated at the start of the simulation from problem parameters WSEED is the seed for calculating iteration parameters It is only specified if IPCALC is equal to zero IPRSIP is the printout interval for SIP If IPRSIP is equal to zero it is changed to 999 The maximum head change positive or negative is printed for each iteration of a time step whenever the time step is an even multiple of IPRSIP This printout also occurs at the end of each stress period regardless of the value of IPRSIP Appendix A 24 Processing Modflow Slice Successive Overrelaxation Package Input to the Slice Successive Overrelaxation Package
81. 22 Comparison of simulation results to analytical solution developed by Oakes and Wilkinson 1972 Applications and Sample Problems 5 26 Processing Modflow 5 10 Simulation of a Flood in a River Location PMWIN EXAMPLES STRI EX2 Problem Description and Modeling Approach This example is from the second test problem of ths STR1 Package The function of the STR1 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 Fig 5 20 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 also only to the river as river stage decreases with time The analytical solution from Cooper and Rorabaugh 1963 p 355 358 is 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 as 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 a
82. AKAGE 0000000E 00 0 0000000E 00 0 0000000E 00 HEAD DEP BOUNDS 0000000E 00 0 0000000E 00 0 0000000E 00 STREAM LEAKAGE 0000000E 00 0 0000000E 00 0 0000000E 00 INTERBED STORAGE 0000000E 00 0 0000000E 00 0 0000000E 00 SUM OF THE LAYER 2989511E 02 6 2958285E 02 3 1225383E 05 ZONE 1 LAYER FLOW TERI IN OUT IN OUT all flow terms are zero because zone 1 lies only in the first layer ZONE 2 LAYER FLOW TERI IN OUT IN OUT all flow terms are zero because zone 2 lies only in the second layer ZONE 2 LAYER FLOW TERI IN OUT IN OUT STORAGE 0 0000000E 00 0 0000000E 00 0 0000000E 00 CONSTANT HEAD 5 2456958E 03 4 0024151E 03 1 2432807E 03 HORIZ EXCHANGE 0 Q0000000E 00 0 0000000E 00 0 0000000E 00 EXCHANGE UPPER 3 6502272E 04 1 5266858E 04 2 1235413E 04 EXCHANGE LOWER 0 0000000E 00 0 0000000E 00 0 0000000E 00 WELLS 0 Q0000000E 00 1 5000000E 03 1 5000000E 03 DRAINS 0 0000000E 00 0 0000000E 00 0 0000000E 00 RECHARGE 0 0000000E 00 0 0000000E 00 0 0000000E 00 ET 0 0000000E 00 0 0000000E 00 0 0000000E 00 RIVER LEAKAGE 0000000E 00 0000000E 00 0000000E 00 HEAD DEP BOUNDS 0000000E 00 0000000E 00 0000000E 00 STREAM LEAKAGE 0000000E 00 0000000E 00 0000000E 00 INTERBED STORAGE 0000000E 00 0000000E 00 0000000E 00 SUM OF THE LAYER 6107184E 03 6550838E 03 4365413E 05 WATER BUDGET OF SELECTED ZONES IN OUT IN OUT ZONE 1 6 2989511E 02 2958285E 02 1225383E 05 ZONE 2 5 6107184E 03 6550838E 03 4365413
83. CBC Specified concentration TG CBC Specified concentration TR CBC Specified concentration TRC CBC Specified concentration TST CBC Specified concentration TW CBC Specified concentration MT3 ZONE Specified concentration MT5 ZONE Specified concentration MT6 ZONE Specified concentration MT7 ZONE Specified concentration MT8 ZONE Specified concentration MT9 ZONE Specified concentration M10 ZONE Specified concentration MT3D Dispersion Package at of at of of of of of of of at of of at DPS TAL CBC Longitudinal dispersivity M1 ZONE Longitudinal dispersivity MT3D Chemical Reaction Package CHE MT3D Advection Package ADV Other Reserved File Extensions Processing Modflow constant head cells evapotranspiration flux general head boundary cells river recharge flux stream injection wells injection wells river evapotranspiration flux general head boundary cells recharge flux stream constant head cells User specified settings for the Dispersion Package User specified settings for the Chemical Reaction Package User specified settings for the Advection Package see Appendix 7 Most options and setting of a model is saved in this file is a binary file for saving the user specified bores and observations is a binary file for saving the settings of the parameter list saved automatically by PMWIN Extension Description GRD Grid
84. E 01 TOTAL IN 0 68083E 01 OUT OUT STORAGE 0 00000 STORAGE 0 00000 CONSTANT HEAD 0 48096E 01 CONSTANT HEAD 0 48096E 01 WELLS 0 2E 01 WELLS 0 20000E 01 TOTAL OUT 0 68096E 01 TOTAL OUT 0 68096E 01 IN OUT 0 13150E 04 IN OUT 0 13150E 04 PERCENT DISCREPANCY 0 02 PERCENT DISCREPANCY 0 02 Fig 2 8 Volumetric budget for the entire model written by MODFLOW There are situations in which it is useful to calculate flow terms for various subregions of the model To facilitate such calculations flow terms for individual cells are saved in the file Your First Groundwater Flow Model with PMWIN Processing Modflow 2 11 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 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 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
85. E 05 WATER BUDGET OF THE WHOLE MODEL DOMAIN FLOW TERM IN OUT IN OUT STORAGE 0 0000000E 00 0 0000000E 00 0 0000000E 00 CONSTANT HEAD 6 8082534E 02 4 8095688E 02 1 9986846E 02 WELLS 0 0000000E 00 2 0000000E 02 2 0000000E 02 DRAINS 0 0000000E 00 0 0000000E 00 0 0000000E 00 RECHARGE 0 0000000E 00 0 0000000E 00 0 0000000E 00 ET 0 0000000E 00 0 0000000E 00 0 0000000E 00 RIVER LEAKAGE 0 0000000E 00 0 0000000E 00 0 0000000E 00 HEAD DEP BOUNDS 0 0000000E 00 0 0000000E 00 0 0000000E 00 STREAM LEAKAGE 0 0000000E 00 0 0000000E 00 0 0000000E 00 INTERBED STORAGE 0 0000000E 00 0 0000000E 00 0 0000000E 00 SUM 6 8082534E 02 6 8095684E 02 1 3150275E 05 DISCREPANCY 0 02 The value of the element i j of the following flow matrix gives the flow rate from the i th zone into the j th zone Where i is the column index and j is the row index Your First Groundwater Flow Model with PMWIN 2 14 FLOW Fig Processing Modflow MATRIX 1 2 0 0000 1 5267E 04 3 6502E 04 0 0000 2 10 continued Output from the Water Budget Calculator To read and save the calculated hydraulic heads of each layer Choose Result Extractor from the Run menu A Result Extractor dialog box appears Fig 2 11 You can choose a result type from the Result Type drop down box In the Time Layer group you can specify the number of the layer stress period and time step from which the result should be read The spreadsheet displays a series of columns and rows T
86. EN is provided as Always_3 the filling of these same columns will require twice as many model runs as there are parameters within the group however the derivatives will be calculated with greater accuracy and this will probably have a beneficial effect on PEST s performance If FORCEN is set to Switch derivatives calculation for all adjustable group members will begin using the forward difference method switching to the central method for the remainder of the estimation process on the iteration after the relative objective function reduction between successive optimisation iterations is less than PHIREDSWH defined in the Control Data 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 optimisation process when accuracy is not critical to objective function improvement and accuracy to take precedence over speed later in the process when realisation of a normally The Modeling Environment Processing Modflow 3 57 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 e DERINCMUL If derivatives are calculated using one of the three point methods see DERMTHD the parameter increment is first added to the current parameter value prior to a model run and then subtracted pr
87. EXDP lt 0 the extinction depth from the preceding stress period will be reused is the layer indicator IEVT read flag It is used only if the ET option NEVTOP is equal to two f INIEVT 0 an array containing the layer indicators IEVT will be read f INIEVT lt 0 layer indicators used during the preceding stress period will be reused is the elevation of the ET surface is the maximum ET rate volume of water per unit area L T is the ET extinction depth is the layer indicator array For each horizontal location it indicates the layer from which ET is removed It is needed only if the ET option NEVTOP is equal to two Processing Modflow A 21 General Head Boundary Package Input for the General Head Boundary Package GHB1 is read from the unit specified in IUNIT 7 FOR EACH SIMULATION 1 Data MXBND IGHBCB Format I10 I10 FOR EACH STRESS PERIOD 2 Data ITMP Format 110 3 Data Layer Row Column Head Cond Format 110 I10 I10 F10 0 F10 0 The 3 data normally consists of one record for each GHB If ITMP is negative or zero the 3 data is not read Explanation of Fields Used in Input Instructions MXBND IGHBCB ITMP Layer Row Column Head Cond is the maximum number of general head boundary cells at one time is a flag and a unit number If IGHBCB gt 0 it is the unit number on which cell by cell flow terms will be recorded whenever ICBCFL see Output Control Options
88. Environment 3 24 Processing Modflow These assumptions can be expressed in equation form as Rog Rega h gt h Rg 0 h lt h d ah R R Ge A h d lt h lt h S 0 Toes where A L L T is the evapotranspiration rate per unit of surface area of water table The evapotranspiration flow rate Q L T drawn from a model cell is Q Rog DELR DELC 3 17 where DELR DELCis the map area of a model cell Q is drawn from only one cell in the vertical column beneath the map area DELR DELC The EVT1 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 ley defines the layer where evapotranspiration is drawn from In either case the Q 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 EVT1 dialog box The layer indicator array is needed only when the second option is used Horizontal Flow Barrier HFB1 The Horizontal Flow Barrier Package Hsieh and Freckleton 1993 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 ho
89. For this reason a mixed option combining both methods is introduced in the MT3D model 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 For more information on the numerical implementation and the effective use of the MT3D model refer to Zheng 1990 1993 or Zheng and Bennett 1995 The Particle Placement Movement parameters required by the Advection Package of MT3D MTADV 1 are explained below The parameters DCEPS NPLANE NPL NPH NPMIN NPMAX and SRMULT are only required by MOC or HMOC The parameters NLSINK and NPSINK are only required by MMOC or HMOC gt MXPART is the maximum number of total moving particles allowed and is used only by the MOC or HMOC solution schemes gt PERCEL is the Courant number or number of cells any particle will be allowed to move in any direction in one transport step Generally 0 5 lt PERCEL lt 1 Values in excess of 1 can be used if the higher order particle tracking method fourth order Runge Kutta algorithm is used throughout the grid Furthermore because all cells in the entire grid are checked when calculating the maximum allowed tracking stepsize there may be a few cells where a particle will move more than one cell s length with PERCEL gt 1 while a particle will only move
90. H 0 an array containing the concentration of recharge flux will be read If INCRCH lt 0 the concentration of recharge flux will be reused from the last stress period For the first stress period the concentration of recharge flux is set to zero by default is the concentration of recharge flux If the recharge flux is positive the recharge acts as a source whose concentration can be specified as desired If the recharge flux is negative the recharge acts as a sink or discharge whose concentration is always set equal to the concentration of the aquifer at the cell where discharge occurs Note that the location and flow rate of recharge discharge are obtained from the flow model directly through the unformatted head and flow file MT3D FLO is a flag indicating whether an array containing the concentration of evapotranspiration flux will be read for the current stress period If INCEVT 0 an array containing the concentration of evapotranspiration flux will be read If INCEVT lt 0 the concentration of Evapotranspiration flux will be reused from the last stress period is the concentration of Evapotranspiration flux Evapotranspiration is the only sink whose concentration can be specified externally Note that the concentration of a sink cannot be greater than that of the aquifer at the sink cell Thus if the Appendix A 40 NSS KSS ISS CSS ITYPE Appendix Processing Modflow sink concentration is specified greater t
91. IB1 CBC IB2 CBC IB3 CBC IB4 CBC 112 ZONE 122 ZONE 132 ZONE 14Z ZONE RCH1 Package RCH CBC RCI CBC RHZ ZONE RIZ ZONE RIV1 Package RIC CBC RIR CBC RIS CBC RCZ ZONE RRZ ZONE RSZ ZONE STR1 Package SBO CBC SEG CBC SFL CBC SRE CBC SRO CBC SSL CBC SST CBC STC CBC STI CBC SWI CBC S1Z ZONE S2Z ZONE S32 ZONE S4Z ZONE S5Z ZONE S6Z ZONE S7Z ZONE S8Z ZONE S9Z ZONE SOZ ZONE WEL1 Package WEL CBC WEZ ZONE Description Evapotranspiration extinction depth Evapotranspiration extinction depth Layer indicator array For each horizontal location which evapotranspiration is removed Maximum evapotranspiration rate L T Elevation of the evapotranspiration surface it indicates the layer from Head on the general head boundary Hydraulic conductance of the interface between the aquifer cell and the general head boundary Head at the general head boundary Hydraulic conductance of the interface between the aquifer cell and the general head boundary Direction of a horizontal flow barrier Hydraulic conductivity divided by the thickness of a horizontal flow barrier Preconsolidation Head Elastic Storage Factor Inelastic Storage Factor Starting Compaction Preconsolidation Head Elastic Storage Factor Inelastic Storage Factor Starting Compaction Recharge flux L T Layer indicator array that defines
92. If ITMP is negative or zero The 3 data is not read Explanation of Fields Used In Input Instructions MXWELL is the maximum number of wells used at any time IWELCB is a flag and a unit number If IWELCB gt 0 it is the unit number on which cell by cell flow terms will be recorded whenever ICBCFL see Output Control Options is set If IWELCB 0 cell by cell flow terms will not be printed or recorded If IWELCB lt 0 well recharge will be printed whenever ICBCFL is set ITMP is a flag and a counter If ITMP lt 0 well data from the last stress period will be reused If ITMP gt 0 ITMP will be the number of wells active during the current stress period Layer is the layer number of the model cell that contains the well Row is the row number of the model cell that contains the well Column is the column number of the model cell that contains the well Q is the volumetric recharge rate A positive value indicates recharge and a negative value indicates discharge Appendix A 18 Processing Modflow Drain Package Input to the Drain Package DRN1 is read from the unit specified in IUNIT 3 FOR EACH SIMULATION 14 Data MXDRN IDRNCB Format 110 I10 FOR EACH STRESS PERIOD 2 Data ITMP Format TIQ 36 Data Layer Row Col Elevation Cond Format 110 110 110 F10 0 F10 0 The 3 data normally consists of one record for each drain 3 data If ITMP is negative or zero the will not be read Explanation of Fields Us
93. Interpolator or Field Generator See chapter 4 for details about the Field Interpolator and Field Generator File Start Position Options o Column J Row 1 Replace Add tT a Canes Maximum Numbers Multiply Hel Column 30 Row 30 Divide p Fig 2 13 The Load Matrix dialog box Your First Groundwater Flow Model with PMWIN Processing Modflow 2 17 Environment Options Fig 2 14 The Environment Options dialog box Processing Modflow SAMPLE MDL File Value Options Help RRS FETS S Sole L 185350 He 111 Besdyette fece Fig 2 15 A contour map of the hydraulic heads in the first layer Your First Groundwater Flow Model with PMWIN 2 18 Processing Modflow Save Plot As Format pr CY File e myprog pmwin demo ex sample dx Fig 2 16 The Save Plot As dialog box for saving graphics in different formats gt To create solid fill plots 1 Choose Recycle from the Parameters menu Data specified in Recycle will not be used by any simulation programs We can use Recycle to save temporary data or to display simulation results graphically 2 Repeat steps 2 to 5 of the foregoing procedure to
94. L PCG2AL ISUM LENX LCV LCSS LCP LCCD L LCHCHG LCLHCH LCRCHG LCLRCH MXITER ITER1 NCOL NROW NLAY 2 IUNIT 13 IOUT NPCOND IF IUNIT 14 GT 0 CALL STRIAL ISUM LENX LCSTRM ICSTRM MXSTRM L 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 L IOUT IF IUNIT 19 GT 0 CALL IBS1AL ISUM LENX LCHC LCSCE LCSCV LCSUB NCOL NROW NLAY IIBSCB IIBSOC ISS IUNIT 19 IOUT IF IUNIT 20 GT 0 CALL CHD1AL ISUM LENX LCCHDS NCHDS MXCHD L IUNIT 20 IOUT Table Al IUNIT assignments given in the main program of MODFLOW IF IUNIT 5 IF IUNIT 7 IF IUNIT 8 Q2Z2QHAEH AH User s own IUNIT_OF_BCF IUNIT_OF_WEL IUNIT_OF_DRN IUNIT_OF_RIV IUNIT_OF_EVT IUNIT_OF_GHB IUNIT_OF_RCH IUNIT_OF_SIP IUNIT_OF_SSOR 11 IUNIT_OF_OC 12 IUNIT_OF_PCG2 13 IUNIT_OF_STR1 14 IUNIT_OF_HFB1 16 IUNIT_OF_IBS1 19 IUNIT_OF_CHD1 20 Table A2 IUNIT assignments saved in the User s own section of PMWIN INI woWmMArAtnaPWNE Appendix A 42 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 vers
95. LES MT3D1 EX1 Problem Description and Modeling Approach 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 10m Groundwater seepage 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 Total simulation time 365 days A numerical model consisting of 46 columns 31 rows and 1 layer was constructed to simulate the problem The configuration of the model is shown in Fig 5 31 The model layer is simulated as a confined layer The top and buttom of the model layer is at an elevaiton of 10 m and 0 m respectively To simulate the groundwater seepage velocity of 1 3 m day constant head boundaries with h 11 m and h 10m are assigned to the west and east side of the model The horizontal hydraulic conductivity is 45 m day A 1 tim 10m Injection Well Q 1 n day 300 m constant head boundary h constant head boundary h y Fig 5 31 Configuration of the model and the location o
96. MT3D Program EAPMWIN MT3DLITE EXE Basic Transport Package e pmwin examples pmex mtbtn1 dat Advection Package e pmwin examples pmex mtadv1 dat Dispersion Package e pmwin examples pmex mtdsp1 dat Chemical Reaction Package e pmwin examples pmex mtrectl dat Sink and Source Mixing e pmwin examples pmex mtssm1 dat Options l Regenerate all input files for MT3D l Generate input files only don t start MT3D Fig 3 51 The Run MT3D dialog box gt The File Table PMWIN uses the user specified data to generate input files of MT3D The Description column gives the name of the packages used in the transport model The path and name of the input file are shown in the Destination column PMWIN generates an input file only if the Generate flag is set to YES You can click on a row to toggle the Generate flag between YES and NO Generally you do not need to worry about these flags as PMWIN will care about the settings See Appendix 4 for details about the generated input files of MT3D The Modeling Environment 3 74 Processing Modflow 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 or you want to run an other model saved in the same subdirectory as the current model Generate input files only don t start MT3D Check this option if you want to run MT3D outside of Windows See OK below gt OK Click OK
97. NA Data Sfv NCOL NROW Input Module U2DREL 6 Data COM NCOL NROW Input Module U2DREL IF IIBSOC IS GREATER THAN ZERO 7 Data ISUBFM ICOMFM IHCFM ISUBUN ICOMUN IHCUN Format I10 I10 I10 I10 I10 I10 FOR EACH TIME STEP IF IIBSOC IS GREATER THAN ZERO 8 Data ISUBPR ICOMPR IHCPR ISUBSV ICOMSV IHCSV Format 110 I10 I10 I10 110 I10 Explanation of Fields Used in Input Instructions ITIBSCB is a flag and unit number If IIBSCB gt 0 it is the unit number on which cell by cell flow terms will be recorded whenever ICBCFL see Output Control Options is set If IIBSCB lt 0 cell by cell flow terms will not be recorded IIBSOC is a flag for selecting output control for each time step If IIBSOC gt 0 output control will be read each time step for printing and recording subsidence total compaction of all layers with interbed storage and compaction and preconsolidation head for all layers with interbed storage If IIBSOC lt 0 subsidence will be printed at the end of each stress period using format 10G11 4 Compaction and preconsolidation head will not be printed and subsidence compaction and preconsolidation head will not be recorded IBQ is an indicator to specify which model layers have interbed storage If IBQ K gt 0 model layer K has interbed storage If IBQ K lt 0 model layer K does not have interbed storage HC is an array specifying the preconsolidation head or preconsolidation stress in terms of head in the aquife
98. Number 30 Size 20 000 Fig 2 3 The Model Dimension dialog box File Options Help HEIS SLAs 1171 338 538 8535 A time independent Mesh Size L T Fig 2 4 The generated model grid The next step is to specify the type of layers gt To assign the type of layers 1 Choose Layer Type from the Grid menu A Layer Options dialog box will appear 2 Clicking a cell of the Type column a drop down button will appear in the current cell If you click on the button a list will drop down which contains all the possible layer types as shown in Fig 2 5 3 Select type 1 for the first layer and type 0 for the second layer 4 Click OK Your First Groundwater Flow Model with PMWIN Processing Modflow 2 5 Layer Options 10 Confined 0 F Plculated 1 Unconfined 2 Confined Unconfined Transmissivity const 3 Confined Unconfined Transmissivity varies 4 Type 0 semi confining layer Fig 2 5 The Layer Options dialog box and the layer type drop down list Now you will specify boundary conditions of the flow model by using the IBOUND array This array contains a code for each model cell which indicates whether 1 the hydraulic head is computed active variable head cell or active cell 2 the hydraulic head is kept fixed at a given value constant head cell or time varying specified head cell or 3 no flow takes place within the cell inactive cell
99. Options Fig 4 23 Interpolation of simulation results to a user specified bore 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 searches the minimum and maximum simulation times and values from the simulation result and put them into the X Axis Time and Y Axis groups Graph Style You can display the time axis X axis either on a linear or logarithmic scale Save Plot As Modeling Tools Processing Modflow 4 33 Use this button to save the graph in Windows bitmap format Note that PMWIN uses the same resolution as Windows to save bitmap files The 24 bits True Color resolution is not supported by PMWIN Do not try to save graphs if you are using True Color gt Data Click this button to display a Value Table dialog box Fig 4 24 showing the observation and calculated values Clicking the Save As button you can save the calculated values in a Observation file see Appendix 2 for the format Observations Calculated Yalues 25 84934 26 25483 26 28266 20 4635 20 05996 20 03227 25 82236 26 22545 26 2531 20 46234 20 06118 2 180 20 03366 Fig 4 24 The Value Tables dialog box Modeling Tools Processing Modflow 5 1 5 Applications and Sample Problems The sample problems contained in this chapter are intended to illustrate the use of PMWIN and the supported programs
100. PMDIS from the Run menu of PMWIN or double click the icon za from the Program Manager A dialog box appears Fig 4 13 The available settings are summarized in Files Gridding Method Search Method and Grid Position Files gt PMWIN Model If you have already opened a model within PMWIN this field gives the model file name If Open A Model First is shown you must click LJ and select a PMWIN model from a standard Open File dialog box A PMWIN model file always has the extension MDL Modeling Tools 4 20 Processing Modflow gt Input File An input file contains the measurement data and must be prepared with other software or text editors Click LSJ to select an existing input file An input file must have the following format N first line of the data file X4 Va fi second line of the data file Xz Voile third line of the data file Xi Yi fi i 1 th line of the data file Xn Yn n last line of the data file Where N 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 the data point i The maximum number of data points is 2000 gt 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 ASCH matrix file Field Interpolator PMWIN Model e pmwin examples pmdis expmdis mdl Input File e pmwin examples pmdis measure dat Output File e pmwin ex
101. Processing Modflow A SIMULATION SYSTEM FOR MODELING GROUNDWATER FLOW AND POLLUTION WEN HSING CHIANG amp WOLFGANG KINZELBACH About the Cover The cover picture shows a landfill in Hamburg Germany The deposit operated from 1935 to 1979 during the operation time it accepted municipal as well as industrial chemical wastes The deposit rises about 40 m above the surrounding terrain and covers an area of about 390 000 m 96 acres Software Licence Agreement Software Licence Agreement This document is a legal agreement between you the end user and the authors By using the software you are agreeing to be bound by the terms of this agreement Licence You have the non exclusive right to use the enclosed Software You have the right to copy the Software onto a single computer and the right for you and others to use that copy of the Software on that single computer You may copy the software onto computers office home laptop provided that only one copy of the Software is used at anytime Where the Software are copied onto multiple computers or is used on a network or file server you must purchase a number of copies of the Software equal to the number of users who will use the Software You may not distribute copies of the Software or documentation to others You may not assign sublicence or transfer this Licence without the written permission of the authors You may not rent or lease the Software without the prior permission o
102. Read one value for each of the NCOL columns This is a single array with one value for each column 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 Appendix Processing Modflow 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 fitting 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 Scientific Software Group Washington DC Anderson M P and W W Woessner 1991 Applied groundwater modeling simulation of flow and advective transport 381 pp Academic Press San Diego CA 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 and A Verruijt 1987 Modeling groundwater flow and pollution D Reidel Publishin
103. SC h gt a e Gaussian model rm C 1 EXP h a cy 4 14 e Exponential model in C 1 EXP h al co 4 15 Where C is the variance of measurement data and will automatically be calculated by PMDIS a the correlation length Co the nugget variance a the slope and w the power factor of the power model w 1 yields the linear model Fig 4 16 The variance C will be calculated by the program Yih Yih oe linear 087 0 67 0 67 0 44 a 0 44 3a 0 24 power 0 2 Co q 1 2 3 4 h 2 5 10 2030 h Fig 4 16 Linear power and logarithmic model Search Method The interpolation algorithms use three search methods to find a certain number of the measurement data points for interpolating a cell value The search methods are SIMPLE QUADRANT and OCTANT PMDIS assumes that the search radius is infinitely large Modeling Tools 4 24 Processing Modflow 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 4 17a and 4 17b 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 points found in the entire model The valid range of Data Per Sector is SIMPLE 3 lt Data Per Sector lt 30 QUADRANT 1 lt Data Per Sector lt 7 OCTANT 1 lt Data Per Sector lt 3 T
104. Specification file IN L Settings of the Layer options MDL Model information file POL PPL RCD Information for the allocation of data arrays TRN Extented time parameter file TRS is a Trace file see above WBL CBC Subregions for calculating of water balance _83 CBC Recycle WBZ ZONE Subregions for calculating of water balance Z83 ZONE Recycle The following file extensions are used by PM3 0 only LMK position of model grid and landmarks TRA Time parameter file WET Settings of the BCF2 Package XFD Settings of import of DXF maps MAP Reserved for the DXF file created by PMCAD Appendix Processing Modflow A 11 Appendix 3 Input Instructions of Modflow These input instructions are intended as a reference for the experienced user PMWIN translates the user specified data to the input files of MODFLOW by using the rules given in these input instructions Most explanations of the input variables are also contained in Chapter 3 Input for the Basic Package BAS1 except for output control is read from unit 1 as specified in the main program Input Instructions For Array Reading Utility Modules There are three array reading utilities modules in MODFLOW U1DREL U2DINT and U2DREL The real two dimensional array reader U2DREL the integer two dimensional array reader U2DINT and the real one dimensional array reader UIDREL read one array control record and optionally a data array in a format specified o
105. 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 The Modeling Environment 3 14 Processing Modflow concentration associated with Well River Stream Recharge Evapotranspiration and General Head Boundary Packages as well as Constant Head cells Using the buttons Save and Load 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 given in Appendix 2 MODFLOW allows the time step to increase as the simulation progesses It uses the following formulae to increase the lengths of time steps as a geometric progression PERLEN 1 TSMULT Delt 1 1 TSMULT 3 1 Delt m 1 TSMULT Delt m 3 2 where PERLENis the length of a stress period TSMULTis the time step multiplier NSTPis the number of time steps and Delt m is the length of time step m in a stress period The length of stress periods is not relevant to steady state flow simulations However if you want to perform contaminant transport simulation with MT3D at a later time you must specify the actual time length in the table Because the explicit transport solution MT3D version 1 85 has certain stability criteria associated with it the length of a time step used for a head solution may be too lar
106. T NCOL NROW Input Module U2DINT Explanation of Fields Used in Input Instructions NEVTOP EVTICB NSURF NEVTIR NEXDP NIEVT SURF EVTR EXDP IEVT Appendix is the Evapotranspiration ET option code ET parameters ET surface maximum ET rate and extinction depth are specified in two dimensional arrays SURF EVTR and EXDP with one value for each vertical column Accordingly ET is calculated for one cell in each vertical column The option codes determine for which cell in the column ET will be calculated f NEVTOP 1 ET is calculated only for cells in the top grid layer f NEVTOP 2 the cell for each vertical column is specified by the user in array EVT is a flag and a unit number f IEVTCB gt 0 it is the unit number on which cell by cell flow terms will be recorded whenever ICBCFL see Output Control Options is set f IEVTCB lt 0 cell by cell flow terms will not be printed or recorded is the ET surface SURF read flag f INSURF gt 0 an array containing the ET surface elevation will be read f INSURF lt 0 the ET surface from the preceding stress period will be reused is the maximum ET rate EVTR read flag f INEVTR 0 an array containing the maximum ET rate will be read f INEVTR lt 0 the maximum ET rate from the preceding stress period will be reused is the extinction depth EXDP read flag f INEXDP gt 0 an array containing the extinction depth EXDP will be read f IN
107. T then tries another lambda less by a factor of RLAMFAC than the first If the objective function is lower than for the first lambda and still above PHIRATSUF of the starting objective function PEST reduces lambda yet again otherwise it increases lambda to a value greater by a factor of RLAMFAC than the first lambda for the iteration If in its attempts to find a more effective lambda by lowering and or raising lambda in this fashion the objective function begins to rise PEST accepts the lambda and the corresponding parameter set giving rise to the lowest objective function for that iteration and moves on to the next iteration Alternatively if the relative reduction in the objective function between the use of two consecutive lambdas is less than PHIREDLAM PEST takes this as an indication that it is probably more efficient to begin the next optimisation iteration than to continue testing the effect of new Marquardt lambdas Thus if The Modeling Environment Processing Modflow 3 47 S lt PHIREDLAM 3 43 oe where D is the objective function value calculated during optimisation iteration i using the j th trial lambda PEST moves on to iteration i 1 A suitable value for PHIREDLAM is often around 0 01 If it is set too large the criterion for moving on to the next optimisation 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 e
108. a linear problem MXITER should be 1 unless more than 50 inner iterations are required when EXITER could be as large as 10 A larger number generally less than 100 is required for a nonlinear problem is the maximum number of inner iterations For nonlinear problems ITER1 usually ranges from 3 to 10 a value of 30 will be sufficient for most linear problems is the flag used to select the matrix preconditioning method The following options are available NPCOND PRECONDITIONING METHOD 1 Modified Incomplete Cholesky for use on scalar computers 2 Polynomial for use on vector computers or to conserve computer storage is the head change criterion for convergence in units of length When the maximum absolute value of the head change at all nodes during an iteration is less than or equal to HCLOSE and the criterion for RCLOSE is satisfied see below iteration stops Commonly HCLOSE equals 0 01 is the residual criterion for convergence in units of cubic length per time When the maximum absolute value of the residual at all nodes during an iteration is less than or equal to RCLOSE and the criterion for HCLOSE is satisfied see above iteration stops Commonly RCLOSE equals HCLOSE For nonlinear problems convergence is achieved when the convergence criteria are satisfied on the first inner iteration is the relaxation parameter used with NPCOND 1 MICCG Usually RELAX 1 0 but for some problems value of 0 99 0 98 or 0 97 will reduce the
109. a 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 can save the cell data in an ASCII Matrix file by clicking the Save button and specifying the file name in a standard file open dialog box An ASCII Matrix file can be loaded into the spreadsheet at a later time The format of the ASCII matrix file is described in Appendix 2 The Modeling Environment 3 62 Parameter Browse Matrix Column Width 2 9221E 04 3 38198E 04 Horizontal Hydraulic Conductivity 1 01632E 03 4 39978E 04 4 6885E 04 5 73478E 04 El 14 6 92151E 04 9 11934E 04 2 68443E 04 3 47362E 04 6 01774E 04 7 56159E 04 4 68605E 04 4 68754E 04 1 58081E 03 1 23178E 03 1 22076E 4 53184E 6 66174E 04 2 90403E 04 5 48027E 04 7 85387E 04 3 13501E 4 3 01564E 04 2 44377E 04 2 15774E 04 1 33784E 04 9 60952E 04 5 78082E 04 2 77989E 04 2 83251E 04 4 10016E 6 04779E 0017704 9 28068E 04 9 45196E 04 8 25394E 04 8 87563E 04 1 13588E 03 1 37807E 03 1 75707E 03 001329 2 90043E 03 2 89293E 03 1 25639E 03 1 07987E 2 62047E 03 1 62675E 03 0016789 1 57719E 03 1 24068E 03 1 39345E 03 5 71724E 04 5 03016E 04 1 08088E 8 53189E 7 53322E 04 4 25868E 04 5 15742E 04 3 5221E 04 1 45341E 04 1 97768E
110. a way to delete particles Zoom In Allows you to drag a zoom window over a part of the model Zoom Out Forces PMPATH to display the entire model grid BAakE Particle color Allows a user to select a color for new particles from the standard color dialog box 4 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 by the particle tracking step length Modeling Tools Processing Modflow 4 9 K 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 I gt Run particles forward step by step Executes backward particle tracking for a user specified particle tracking step length gt 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 MDL The flow simulation with MODFLOW must be complete before you can open a model By default PMPATH reads the unformatted binary files HEADS DAT and BUDGET DAT from the same directory as the loaded model Set particle Use the following two methods to place particles in the current layer The curre
111. ach The hydraulic conductivity of the streambed deposits is 4 x 10 ft s Applications and Sample Problems 5 28 Processing Modflow Columns 1 2 3 4 5 6 e stream segment dots indicate section of stre used to define a segment Arrow indicates th direction of flow segment number 2 reach number within a segment section of stream not included in model simul Fig 5 25 Example numbering system of streams and diversions after Prudic 1988 Applications and Sample Problems Processing Modflow 5 29 5 11 Simulation of the Storage Depletion Location PAWIN EXAMPLES IBS1I EX1 Problem Description and Modeling Approach This example is from the first test problem of the Interbed Storage IBS1 Package Leake and Prudic 1991 The finite difference grid consists of two layers with 10 rows and 12 columns of cells The first and last column of cells in both layers are constant head boundaries so that the other 10 active columns of cells are a flow region subject to head and storage changes The grid dimensions for each cell are 1 000 m along both rows and columns Each layer has a transmissivity of 1 000 m d and a storage coefficient of 0 0001 The configuration of the model is shown in Fig 5 26 The starting head in the active area specifies a uniform gradient of 0 001 along the rows Th
112. ach layer 2 Data TRPT NLAY Input Module U1DREL one value for each layer Bs Data TRPV NLAY Input Module U1DREL one value for each layer 4 Data DMCOEF NLAY Input Module U1DREL one value for each layer Explanation of Fields Used in Input Instructions AL is the longitudinal dispersivity L for each cell in the grid TRPT is the ratio of the horizontal transverse dispersivity to the longitudinal dispersivity TRPV is the ratio of the vertical transverse dispersivity to the longitudinal dispersivity DMCOEF is the effective molecular diffusion coefficient Set DMCOEF 0 if the effect of molecular diffusion is considered unimportant Appendix Processing Modflow A 39 Sink amp Source Mixing Package Input to the Sink amp Source Mixing Package MTSSM1 is read on unit 4 which is preset in the main program of MI3D The input file is needed if any sink or source option is used in the flow model including the constant head or general head dependent boundary conditions The classification of the sink source type used in MT3D is the same as that used by MODFLOW FOR EACH SIMULATION 1 Data FWEL FDRN FRCH FEVT FRIV FGHB Format L2 L2 L2 L2 L2 L2 2 Data MXSS Format I10 FOR EACH STRESS PERIOD Enter the 3 data if FRCH T 3 Data Format I10 INCRCH Enter the 4 data if FRCH T and INCRCH gt 0 4 Data CRCH NCOL NROW Input Module U2DREL Enter the 5 data if FEVT T
113. 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 Modeling Tools Processing Modflow 4 15 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 will 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 other faces A particle entering such a cell may be discharged or may leave the cell again In the finite difference approach however it is not possible 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 forwa
114. am e pmwin modflow modflow exe Basic Package e pmwin examples sample bas dat Yes Block Centered Flow BCF1 2 e pmwin examples sample bcf dat Yes Output Control e pmwin examples sample oc dat Yes Well e pmwin examples sample wel dat Yes Solver PCG2 e pmwin examples sample pcg2 dat Yes Modpath Vers 1 x e pmwin examples sample main dat Yes Modpath Vers 329 e pmwin examples sample main30 dat O Options Regenerate all input files for MODFLOW Check the geometrical setting up of the model Cancel l Generate input files only don t start MODFLOW Fig 2 7 The Run Modflow dialog box Check Simulation Results and Produce Output During a flow simulation MODFLOW writes a detailed run record to the file path OUTPUT DAT where path is the directory in which your model data are saved If a flow simulation is successfully complete MODFLOW saves the simulation results in various unformatted binary files as listed in Table 2 1 Prior to running MODFLOW the user may Your First Groundwater Flow Model with PMWIN 2 10 Processing Modflow control the output of these unformatted binary files by choosing Output Control gt Modflow from the Packages menu The output file path INTERBED DAT will only be generated if the Interbed Storage Package is activated see Chapter 3 for details about the Interbed Storage Package For checking the simulation results MODFLOW calcula
115. ameter as seen by the model PEST optimising instead the parameter b where b by o s 3 48 Here b is the parameter optimised by PEST b is the parameter seen by the model while s and o are the scale and offset for that parameter If you wish to leave a parameter unaffected by scale and offset enter the SCALE as 1 0 and the OFFSET as 0 0 Group Definitions and Derivative Data Name is the group name given by PMWIN The group name of the first parameter group is G1 The group name of the second parameter group is G2 and so on The maximum number of paramter groups is 150 Description is a place for you to take notes A maximum of 120 characters is allowed INCTYP and DERINC INCTYP can be Relative Absolute or Rel_to_max If it is Relative the increment used for forward difference calculation of derivatives with respect to any parameter belonging to the group is calculated as a fraction of the current value of that parameter that fraction is provided as the real variable DERINC If INCTYP is Absolute the parameter increment for parameters belonging to the group is fixed being again provided as the variable DERINC Alternatively if INCTYP is Rel_to_max the increment for any group member is calculated as a fraction of the group member with highest absolute value that fraction again being DERINC See Section 2 3 of the PEST manual for a full discussion of the methods used by PEST to calculate parameter derivatives Thus if INCTYP
116. amination 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 This example is posed to demonstrate the capability of the BCF2 Package to simulate mounding of the water table through multiple model layers The hypothetical model is from the second test problem of the BCF2 Package The conceptual model consists of a rectangular unconfined aquifer overlain by a thick unsaturated zone Fig 5 16 The horizontal hydraulic conductivity is 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 constant head boundary that surrounds the aquifer 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 system needs to be simulated The problem is simulated using a grid of 40 rows 40 columns and 14 layers Fig 5 16 A uniform horizontal grid spacing of 125 feet 38 1 m is
117. amples pmdis gridded dat Gridding Method Files Search Method Shepard s Inverse Distance zl Octant l Weighting Exponent Data Per Sector Coordinates System Grid Position Y amp o Yo A7 Xo 66401 19 Yo 51362 65 A 27 2 A Rotation angle in degree Help Fig 4 13 The Field Interpolator dialog box uli Gridding Method PMDIS provides four gridding methods viz the 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 Modeling Tools Processing Modflow 4 21 interpolation program The interpolation programs are written in FORTRAN and compiled with a 32 bit compiler gt Shepard s inverse distance The Shepard s inverse distance method uses Equation 4 10 for interpolating data to finite difference cells N Beit fea _ f N 4 10 Spee aero i 1 Where d is the distance between data point i and the center of a model cell f is the value at the i th data point F is the weighting exponent and fis the estimated value at the model cell The weighting exponent must be greater than zero and less than or equal to 10 Fig 4 14 shows the effects of different weighting exponents Five data points are regularly distributed along the x axis Using higher expone
118. and M A Collins 1971 General analysis of longitudinal dispersion in nonuniform flow Wat Res Res 7 6 1511 1521 Helm D C 1975 One dimensional simulation of aquifer system compaction near Pixley California 1 Constant parameters Water Resour Res 11 3 465 478 Higgins G H 1959 Evaluation of the groundwater contaminantion hazard from underground neuclear 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 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 Hoschek J and D Lasser 1992 Grundlagen der geometrischen Datenverarbeitung B G Teubner Stuttgart Germany 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 Jorggensen D G 1980 Reletionship between basic
119. and the coordinates Xo Yo of the upper left corner of the grid PMPATH always displays the model grid parallel to the Top view window The relation between the model grid and the x y z Cartesian coordinate system is illustrated in Fig 4 6 The Top view window displays the construction of the current model layer and the projection of pathlines on the IJ plane The Cross section windows display the projection of pathlines on the IK and JK planes An Environment Options dialog box of PMPATH see below allows a user to change the appearances of these windows The projection of pathlines on the cross sections is 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 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 7 two particles start from the same two dimensional cell at the 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 usin
120. and times data PMPATH calculates and shows the pathlines and travel time marks 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 PMPATH EXAMPLE MDL 7 Crean 7 4429E 03 09 25 24 1 714E 03 2 469E 03 1 100E 01 25 5 1 1 3283E 01 Fig 4 1 PMPATH in operation 1 3793E 05 Both forward and backward particle tracking are allowed for steady state and transient flow simulations For transient flow simulations particles can start from 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 goes further until all particles leave the model or until the user specified time limit is reached The time length of a single particle tracking step and the allowed number of tracking steps can be Modeling Tools 4 2 Processing Modflow specified Furthermore 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 protectio
121. ansmissivity flag to User Specified if you want to specify transmissivity directly gt Leakance For flow simulations involving more than one layer you must specify a vertical transmission or leakage term know as vertical leakance or VCONT array for each cell except for cells in the bottom layer If the Leakance flag is set to Calculated PMWIN calculates VCONT by using The Modeling Environment 3 12 Processing Modflow user specified vertical hydraulic conductivity and the elevations of the top and bottom of each layer Set the Leakance flag to User Specified if you want to specify VCONT vertical leakance directly See Parameters menu for more information about how to calculate VCONT gt Storage Coefficient For transient flow simulations MODFLOW requires dimensionless storage terms specified for each model layer For a confined layer these storage terms are given by the confined storage coefficient specific storage L x layer thickness L If the Storage Coefficient flag is Calculated PMWIN uses user specified specific storage and the elevations of the 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 directly For an unconfined layer the storage values are equal to specific yield The setting of the Storage Coefficient flag has no influence on the input of specific yield Boundary Cond
122. ant Head Drain Scaling factor for the height KX Ghb Cells es River Stream E X sturry wall visible Head Drawdown Minimum Maximum CE Interval 0 04050 4 Velocity Vectors L visible Vector size 25 4 Fig 4 9 The Environment Options dialog box Modeling Tools Processing Modflow 4 13 e Grid Appearance allows you to change the visibility and appearance color of each simulated hydraulic elements A simulated hydraulic element is visible if the corresponding check box is checked To select a new color click the colored button next to the check box and select a color from the Color dialog box e Contours PMPATH displays contours based on the simulated heads or drawdowns if the Visible box is checked To select a new color click the colored button next to the check box and select a color from the Color dialog box The contour interval is automatically chosen such that 11 contours from the lower limit Minimum to the upper limit Maximum of the cell data are displayed Each time you activate the Environment Options dialog box Minimum and Maximum are set to the lower and upper limits of the heads or drawdowns found in the current layer and time step Different contour levels can be obtained by changing Maximum Minimum and Interval e Velocity Vectors describe the directions of water movement at any instant of a given time step of the simulation defined in Current Time Check the Visible check box the
123. as the number of vertical planes on which initial particles are placed within each cell block refer to Fig 3 22a This fixed pattern works well 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 the vertical direction is desired is number of initial particles per cell to be placed at cells where DCCELL lt DCEPS GeneraLly NPL can be set to 0 since advection is 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 i e the uniform approach Appendix A 36 NPH NPMIN NPMAX SRMULT INTERP NLSINK NPSINK DCHMOC Appendix Processing Modflow is number of initial particles per cell to be placed at cells where DCCELL gt 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 simulation or 32 in three dimensional simulation are rarely necessary If the random pattern is chosen NPH particles are randomly distributed within the cell block If the fixed pattern is chosen NPH is divided by NPLANE to yield the number of particle
124. bulk dry mass of the porous medium at the beginning of each transport step C ik is in equilibrium with solute concentration C in the same cell i j k The rate constant is usually given in terms of the half life t In2 lala 3 37 ra Generally if the reaction is radioactive decay A should be set equal to A However for certain types of biodegradation A may be different from A The linear sorption isotherm assumes that G jik is directly proportional to C The Freundlich isotherm is a non linear isotherm expressed in the following form The Langmuir isotherm is expressed in the form 3 40 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 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 among 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 AD 3 41 The Modeling Environ
125. bution of benzene twenty years after the beginning of benzene migration in the aquifer should be calculated deposit Fig 5 33 Plan view of the model area The parameters used in the model are listed in the following table Horizontal hydraulic conductivity in the second layer 8 0x10 m s Horizontal hydraulic conductivity in the first layer ranges from 0 0003 m s to 0 0006 m s Vertical hydraulic conductivity 4 0x10 m s Recharge 2 5x10 m s 80mm yr Effective porosity 0 2 Longitudinal dispersivity 5 m Distribution coefficient of benzene 2x10 m kg Bulk density of the porous medium of the aquifer 1700 kg m Starting concentration 0 kg m The ratio of horizontal and vertical transverse to longitudinal dispersivity in both layers is 0 1 Applications and Sample Problems 5 38 Processing Modflow Simulation Results The problem is simulated using a grid of 55 rows and 57 columns The aquifer is discretized into two layers Both layers are confined The thickness of the first layer is 8 m and the other 7 m The configuration of the finite difference grid is shown in Fig 5 34 The boundaries of the model area are defined by the Mueggenburger Canal and the rivers Norderelbe and Dove Elbe The rivers and the canal are assumed to be in full hydraulic contact with the aquifer and are treated as constant head boundaries of the model The other boundaries are defined by stream line
126. by PMWIN making sure that every item is consistent with every other item and writing 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 e Check the geometrical setup of the model PMWIN finds errors in the geometrical setting up and writes them to the file CHECK LST if 1 the layer thickness is zero or negative 2 the elevations of the layer top and bottom are not consistent and 3 the starting hydraulic head at a constant head cell is lower than the cell bottom In the last case instead of converting the constant head cell to an inactive dry cell MODFLOW writes an error message to the run record file OUTPUT DAT and stops the simulation gt OK Click OK to start the generation of input files of MODFLOW and PEST In addition PMWIN generates two batch files in your model directory PEST BAT and MODELRUN BAT After having generated all necessary files PMWIN automatically opens a DOS box and runs PEST BAT in the box The batch file MODELRUN BAT is used by PEST BAT Follow the steps below if you want to run PEST outside of Windows 1 Inthe Run PEST dialog box check the option Generate input files only don t start PEST then click OK 2 Leave Windows 3 Change the default path to your model directory 4 Type PEST BAT at the DOS prompt then press enter The Modeling Environment Processing Modflow 3 71 After complet
127. c conductivity HTZ ZONE Transmissivity LEZ ZONE Vertical hydraulic conductivity LKZ ZONE Vertical leakance POZ ZONE Effective porosity SCZ ZONE Storage coefficient STZ ZONE Specific storage Eri ZONE Longitudinal dispersivity YLZ ZONE Specific yield Packages Extension Description CHD1 Package 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 ciz ZONE A non zero value indicates a CHD cell C2Z ZONE Head at the beginning of a stress period Start head C32 ZONE Head at the end of a stress period End head DRN1 Package DRC CBC Hydraulic conductance of the interface between an aquifer and a drain DRE CBC Elevation of drain DCZ ZONE Hydraulic conductance of the interface between an aquifer and a drain DEZ ZONE Elevation of drain EVT1 Package 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 Appendix Processing Modflow A 9 Packages continued Extension EXD CBC EDZ ZONE EEZ ZONE ETZ ZONE EUZ ZONE GHB1 Package GHB CBC GHC CBC GBZ ZONE GCZ ZONE HFB1 Package WAL CBC WAC CBC IBS1 Package
128. c conductivity of both layers is about 10 percent of the horizontal hydraulic conductivity The effective porosity is approximately 25 percent The elevation of the top of the first layer is 10m The thickness of the first layer and the second layer is 13 m and 5 m Your First Groundwater Flow Model with PMWIN 2 2 Processing Modflow respectively A contaminated area lies in the first layer next to the west boundary To clean up the aquifer a fully penetrating pumping well is located next to the east boundary A numerical model has to be developed for this site to calculate the required pumping rate of a well The pumping rate must be large enough so that the contaminated area lies within the capture zone of the pumping well We will use PMWIN to construct the numerical model and use PMPATH to compute the capture zone Starting PMWIN When you run the PMWIN Setup program Setup automatically creates a new program group and new program items for Processing Modflow in Windows You are then ready to start PMWIN from Windows gt To start PMWIN from Windows Double click the Processing Modflow icon When you start PMWIN you see the interface of PMWIN with a Menu bar and a tool bar The tool bar contains an Open Model icon you can click this icon to open a model Run a Steady State Flow Simulation There are four main steps to run a steady state flow simulation 1 Create a flow model 2 Assign model data 3 Perform the flow simulati
129. caled DXF map to a desired position by using X and Y Fig 3 47 uses a triangle as an example to show the use of X Y and the scale factor Y Y 8 6 X SY Y SX X s Y 8 X s Y X A DXF map with a triangle before scaling and shifting The DXF map after scaling and shifting A scale factor s and displacement X Y are used X Fig 3 47 The use of X Y and the scale factor The Modeling Environment Processing Modflow 3 69 3 3 9 The Run Menu You start the parameter estimation or simulation programs or the modeling tools from the Run menu The modeling tools are described in chapter 4 Prior to running a parameter estimation or simulation program PMWIN shows a dialog box and asks for the path of the program and other settings as described below Parameter Estimation PEST Modflow Version User s own zl Modflow Program PEST Program e pmwin modtlow modtiow exe EA PMWIN PESTLITE EXE Basic Package e pmwin examples pest ex1 bas dat Block Centered Flow BCF1 2 e pmwin examples pest ex1 bcf dat bcftpl dai Output Control e pmwin examples pest ex1 oc dat River e pmwin examples pest ex1 riv dat rivtpl dat Recharge e pmwin examples pest ex1 rch dat rchtpl dat Solver PCG2 e pmwin examples pest ex1 pcg2 dat gt Regenerate all input files for MODFLOW and PEST Lox l Generate input files only don t start PEST Perform PESTCHEK prior to runnin
130. carried out The total simulation time is 1x10 seconds The calculated head time curve Fig 5 6 shows that the steady state is reached at t 4x10 s Fig 5 6 Head versus time at the center of the contaminant area Applications and Sample Problems 5 8 Processing Modflow 5 4 Using the Field Interpolator Location PAWIN EXAMPLES PMDIS Problem Description This example illustrates the use of the Field Interpolator Fig 5 7 shows the plan view of the model area the model grid and the locations of measurement points The model grid consists of 70 rows and 60 columns and one layer The measured hydraulic heads and the coordinates of the measurement points are saved in the file MEASURE DAT To obtain the starting head of a flow simulation the measured hydraulic heads should be interpolated to each model cell 65 5 66 0 66 5 67 0 67 5 68 0 515 51 0 Be 51 0 TL xy Ley Re LAL LER LAL LAL 50 5 Le 50 5 URASAN Q PEEL KOE LORY LEY OETA ei EERE EEE TLE Le PORE CORRELL ae LEE BEY EEE ees re LEY ay ERED ORR OTTICI OEE OL LEE LOE LEE LETTER EEO COOOL AEE ERE OOO OBST ORAS OOOO RTT 4 50 07 REEERE LIER 50 0 TREES aan EOS BOP LEAL TLL LER RO OG TLTC LLL ETTET EOE EA OTT TRE OR OORT TY POE A SOOTY OREO SEL x X Xe 5 OTL OOO Ly LOO Ly LOO OEE 49 5 re ORT 149 5 r wa REE ai LDAY COREE ERROR 49
131. ction is simulated RHOB is the bulk density of the porous medium in the aquifer One value is specified for each layer SP1 is the first sorption constant One value is specified each layer The use of SP1 depends on the type of sorption selected i e ISOTHM For linear sorption SP1 is the distribution coefficient For Freundlich sorption SP1 is the Freundlich sorption equilibrium constant For Langmuir sorption SP1 is the Langmuir sorption equilibrium constant SP2 is the second sorption constant One value is specified for each layer The use of SP2 depends on the type of sorption selected i e ISOTHM For linear sorption SP2 is not used but still must be entered For Freundlich sorption SP2 is the Freundlich exponent For Langmuir sorption SP2 is the maximum amount of the solute that can be adsorbed by the soil matrix RC1 is the first order rate constant 1 T for the dissolved phase RC2 is the first order rate constant 1 T for the sorbed phase Generally if the reaction is radioactive decay RC2 should be set equal to RC1 However for certain types of biodegradation RC2 may be different from RC1 Appendix A 38 Processing Modflow Dispersion Package Input to the Dispersion Package MTDSP1 is read on unit 3 which is preset in the main program of MT3D The input file is needed only if the Dispersion Package is used in the simulation FOR EACH SIMULATION 1 Data AL NCOL NROW Input Module U2DREL one array for e
132. ctive function calculated for optimisation iteration i 1 and hence the starting value for optimisation iteration i and Dis the objective function corresponding to a parameter set calculated using the j th Marquardt lambda tested during optimisation iteration i PHIRATSUF which stands for phi ratio sufficient is a real variable for which a value of 0 3 is often appropriate 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 is 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 gt PHIREDLAM If a new old objective function ratio of PHIRATSUF or less is not achieved as the effectiveness of different Marquardt lambdas in lowering the objective function is tested PEST must use some other criterion in deciding when it should move on to the next optimisation iteration This criterion is partly provided by the real variable PHIREDLAM The first lambda that PEST employs in calculating the parameter upgrade vector during any one optimisation iteration is the lambda inherited from the previous iteration possibly reduced by a factor of RLAMFAC unless it is the first iteration in which case RLAMBDA 1 is used Unless through the use of this lambda the objective function is reduced to less than PHIRATSUF of its value at the beginning of the iteration PES
133. d PEST will omit the decimal point from representations of 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 is checked PEST will ensure that the decimal point is always present Parameter List The Parameter List gives an overview of estimated parameters and parameter groups An estimated parameter is defined by using the Zone Input Method of the Data Editor Follow the steps below to define an estimated parameter gt Define an Estimated Paramter 1 From the Parameters or Packages menu select a menu item e g Horizontal Hydraulic Conductivity Well or Drain etc The Data Editor appears 2 Change to the Zone Input Method see section 3 2 3 Draw a zone that covers the 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 GHB river or stream cells you must first use the Cell by cell Input Method to define those cells Then you just need to draw a zone that covers them These cells will have the same pumping rate or conductance during a calibration process It is allowed that the zone covers other cells which are not defined as well or head dependent cells 4 Move the mouse cursor into the zone The zone will be highlight blue 5 Click the right mouse button once The Data Editor shows a dialog box for specifying value s
134. d green and blue are the color components rangeing 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 OPTION OPTION 3 3 7 for details 0 Display only OPTION 1 Replace The cell values are replaced by VALUE OPTION 2 Add VALUE is added to the cell values OPTIOn 3 Multiply The cell values are multiplied by VALUE Appendix Processing Modflow Zone file A zone file can be saved or loaded by the Data Editor by using the item Zones from the Value menu File Format Da Data LABEL 25 Data NZONES XXX XXX XXX XXX The following data data 3 6 repeat NZONES times Bis Data NP 4 Data PARNO 5 Data Value 1 Value 2 Value 3 Value I The following data repeats NP times 6 Data X J Y J Explanation of Fields Used in Input Instructions Value 16 LABEL is the file label It must be PMWIN4000_ASCII_ZONEFILE NZONES is the number of zones Maximum is 20 XXX reserved NP is the number of nodes of each zone The first and the last node must overlap The maximum number of NP is 41 PARNO is the assigned parameter number see section 3 3 6 for how to define an estimated paramter Value I I 1 to 16 Value I are the zone values For aquifer param
135. d Harbaugh 1988 Tk Q gt Qrotal ST 3 5 where T is the transmissivity of layer k and T is the sum of the transmissivities of all layers penetrated by the multilayer well An other possibility to simulate multi layer wells is to set a very large vertical hydraulic conductivity or vertical leakance e g 1 m s or 0 1 1 s to all cells of the well The injection or pumping rate for each penetrated layer can be equal to the total rate Q otal divided by the number of the penetrated layers In this case the exact rates for each penetrated layer will be calculated by MODFLOW implicitly The exact flow rates can be obtained by using the Water Budget Calculator See Chapter 2 for how to calculate subregional water budgets Drain DRNI1 Drains are defined by using the Data Editor to assign two values to model cells Fig 3 12 Drain hydraulic conductance C L T Median elevation of the Drain d L The values C and dare shown on the Statusbar 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 is always zero regardless
136. d cell by cell flow terms 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 e Tracking Step To select a time unit for Step length click the down arrow on the Unit drop down box The particle tracking step length is the time length that particles may move when the buttons or Modeling Tools 4 14 Processing Modflow are pressed Maximum steps is the allowed number of particle tracking steps Each time you press the buttons J or gt particles may move backward or forward for a time length defined by the product of Step length and Maximum steps Particle Tracking Options Current Time Tracking Step Time Mark Stress period Unit i 7 i Interval 1 seconds el 1 al Time step Step length Top view Cross section 1 i 31536000 F Visible F Visible Maximum steps Size Size a Simulation Mode C Flowlines use the flow field from the current time step OK Pathlines use transient flow fields Stop Condition Cancel Particles stop when they enter cells with internal sinks Particles stop when the simulation time limit is reached Recharge C Assign recharge to the top face of cells C Assign recharge to the bottom face of cells Assign recharge to top and bottom cell faces C Treat recharge as a distributed source Evapatrancspiration Assign evapotranspirat
137. d layer NRCHOP 2 Vertical distribution of recharge is specified in array IRCH NRCHOP 3 Recharge is applied to the highest active cell in each vertical column A constant head node intercepts recharge and prevents deeper infiltration IRCHCB is a flag and a unit number f IRCHCB gt 0 it is the unit number on which cell by cell flow terms will be recorded whenever ICBCFL see Output Control Options is set f IRCHCB lt 0 cell by cell flow terms will not be printed or recorded INRECH is the RECH read flag f INRECH gt 0 an array of recharge fluxes RECH is read f INRECH lt 0 recharge rates from the preceding stress period are used INIRCH is the IRCH read flag When NRCHOP is two f INIRCH gt 0 an array of layer numbers IRCH is read f INIRCH lt 0 the array IRCH used in the preceding stress period is reused Note When NRCHOP is one or three INIRCH is ignored RECH is the recharge flux L T Read only if INRECH is greater than or equal to zero IRCH is the layer number array that defines the layer in each vertical column where recharge is applied Read only if NRCHOP is two and if INIRCH is greater than or equal to zero Appendix Processing Modflow A 23 Strongly Implicit Procedure Package Input to the Strongly Implicit Procedure Package SIP is read from the unit specified in IUNIT 9 FOR EACH SIMULATION 1 Data MXITER NPARM Format I10 I10 2 Datay ACCL HCLOSE IPCALC WSEED IPRSIP Format F10 0 F
138. del layer can consist of 2000 x 2000 cells Of course a sufficiently large harddisk must be avaiable to store the forthcoming result files PMWIN provides comprehensive supports to the parameter estimation program PEST Users just need to define zones of parameters and send them to a Parameter List This is all accomplished with a click of the mouse PMWIN provides a Layer Options dialog box Transmissivity vertical leakance and storage coefficient of each layer can be specified by the user directly or will be calculated by applying a particular rule e g Transmissivity Hydraulic Conductivity x Layer Thickness The choice for each of these parameters is accomplished by choosing between Calculated or User Specified in the Layer Options dialog box Three additional packages of MODFLOW are supported by PMWIN They are the Horizontal Flow Barrier Package HFB1 for easily simulating slurry walls the Time Variant Specified Head Package CHD1 and the Interbed Storage Package IBS1 for simulating transient storage and calculating compaction and subsidence of an aquifer due to changes of hydraulic heads PMWIN provides a powerful Result Extractor Normally simulation results from Modflow or MT3D are saved unformatted binary and cannot be viewed The unformatted simulation result files include hydraulic head drawdown cell by cell flow terms preconsolidation head compaction subsidence and concentration The Result Extractor allows the us
139. des of the model are assumed to be constant head boundaries with hydraulic heads of 9 8925 and 9 m respectively The pumping rate of the wells should be estimated such that the hydraulic head in the center of the contaminated area in the steady state is reduced to 8 m Furthermore the duration until the steady state is reached should be calculated E pumping wells Fig 5 4 Configuration of the remediation measures Applications and Sample Problems Processing Modflow 5 7 No flow boundary 9 892 9 0m slurry wall Constant head boundary h Constant head boundary h No flow boundary 1785 m gt Fig 5 5 Configuration of the groundwater model Simulation Results The pumping rates of the wells are defined as an estimated parameter by using a zone that covers all four wells An observation bore is set at the center of the contaminated area as shown in Fig 5 4 The observed head at time 1 is set at 8 m the remediation objective The simulation time for the steady state calibration parameter estimation is also set to 1 The pumping rate of each well estimated by PEST is about 7 9x10 m s To calculate the duration until the steady state is reached the estimated pumping rate of 7 9x10 m s is specified to each well A transient simulation with one stress period subdivided into 25 equal time steps is
140. e Search And Modify Parameter Transmissivity Ignore Inactive Cells 0 Display Only 0 Display Only 0 Display Only 0 Display Only 0 Display Only Display Only Display Only Display Only Display Only Fig 3 41 The Search and Modify dialog box Processing Modflow MT3D1EX6 MDL File Value Options Help R Bolg fee 2 6735 102 9661 119 4 9 3 Steady state Recycle H Fig 3 42 A solid fill plot shows the pumping wells and a concentration distribution of a remediation case described in Zheng 1990 The Modeling Environment Processing Modflow 3 65 gt Parameter drop down box For particular packages in which a cell has more than one value e g River Package this drop down box contains the available parameter type s You choose a parameter type for which the Search and Modify operation will apply gt Ignore Inactive Cells If Ignore Inactive Cells is checked the Search and Modify operation will not apply to inactive cells gt Spectrum Using Spectrum the colors in the Color column can be aut
141. e starting head values in the constant head columns also specify a gradient of 0 001 along the rows over the entire grid but at a level exactly 10 m lower than the starting heads in the active area of the model Thus if the transient solution is allowed to run until steady state conditions are reached the head at each interior cell will be exactly 10 m below the corresponding starting head For this example compressible interbeds are assumed to occur in the aquifer represented by the upper layer The preconsolidation head is assumed to be 5 m below the starting head at each cell The elastic storage factor the sum of the products of thickness and elastic skeletal specific storage for interbeds in the upper layer is assumed to be 0 0001 at each cell Similarly the inelastic storage factor is assumed to be 0 001 at each cell m 11im Constant Head Boundary h x G 5 oa oo o o x au S D a 6 lt 1100 m gt Fig 5 26 Configuration of the model and the location of the observation point Simulation Results Within 1 000 days of simulation time head values at all cells will be within about 0 001 m of the final steady state value The volumetric budget for the simulation is shown in table 5 1 The correct volume of water released by the interbeds can be computed as the product of total area Applications and Sample Problems 5 30 Proc
142. e Zone file is given in Appendix 2 Search and Modify Use the Search and Modify dialog box Fig 3 41 if you want to automatically modify a part of the cell data or if you want to create solid fill plots for example Fig 3 42 based on the cell data The items of the dialog box are described below gt The Trace Table You define a search range and its attributes in a row of the table A row is active when the Active flag is YES The search range is given by the minimum lower limit and the maximum upper limit The fill color of each search range is given in the Color column The color is assigned to the finite difference cells that have a value located within the search range The colors in the Color column can be automatically assigned so you get a gradational change from one color to another see Spectrum below To change the color individually double click on the colored cell of the table then select a new color from the Color dialog box According to the user specified value in the Value column and the operation option in the Options column in the active rows you The Modeling Environment 3 64 Processing Modflow can easily modify the cell values The available operation options 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 is added to the cell values Multiply The cell values are multiplied by the user specified valu
143. e a L is the longitudinal dispersivity o L is the horizontal transverse dispersivity a7 L is the vertical transverse dispersivity D L T is the effective molecular diffusion coefficient v Vp Vz LT are components of the flow velocity vector along the x y and z axes and ol vl vy 3 32 Using the Data Editor you specify the longitudinal dispersivity a for each finite difference cell The following values must be specified for each layer in the Dispersion Package MTDSP1 dialog box Fig 3 24 gt TRPT is the ratio of the horizontal transverse dispersivity to the longitudinal dispersivity gt TRPV is the ratio of the vertiocal transverse dispersivity to the longitudinal dispersivity gt DMCOEFF is the effective molecular diffusion coefficient The Modeling Environment Processing Modflow 3 35 Dispersion Package MTDSP1 You need to specify the following values for each layer When finished click OK to edit the longitudinal dispersivity L TRPT the ration of the horizontal transverse dispersivity to the longitudinal dispersivity TRPY the ration of the vertical transverse dispersivity to the longitudinal dispersivity DMCOEF the effective molecular diffusion coefficient L 2 T Fig 3 24 The Dispersion Package MTDSP1 dialog box Chemical Reaction MTRCT1 Chemical reactions supported by the MT3D transport model include equilibrium controlled sorptio
144. e a Flow Model Assign Model Data Perform the Flow Simulation Check Simulation Results and Produce Output The Modeling Environment The Grid Editor The Data Editor PMWIN Menus The File Menu The Grid Menu The Parameters Menu The Packages Menu The Source Menu The Estimation Menu The Value Menu The Options Menu The Run Menu Modeling Tools The Advective Transport Model PMPATH The Semi analytical Particle Tracking Method PMPATH Modeling Environment PMPATH Options PMPATH Output Files The Field Interpolator PMDIS The Field Generator PMFGN The Results Extractor The Water Balance Calculator The Graph Viewer 5 Applications and Sample Problems 5 1 The Theis Solution 5 2 Model Calibration with PEST 5 3 Estimation of Extraction Rates with PEST 5 4 Using the Field Interpolator 5 5 An Example of Stochastic Modeling 5 6 Simulation of a Two Layer Aquifer System in which the Top Layer Converts between Wet and Dry 5 7 Simulation of a Water Table Mound Resulting from Local Recharge 5 8 Simulation of a Perched Water Table 5 9 Simulation of an Aquifer System with Irregular Recharge and a Stream 5 10 Simulation of a Flood in a River 5 11 Simulation of the Storage Depletion 5 12 Simulation of a Non declining Cyclical Ramp Load Problem 5 13 Two Dimensional Transport in a Uniform Flow Field 5 14 A Field Application Appendix 1 Limitations of PMWIN 2 Files and Formats 3 Input Instructions of MODFLOW 4 Input Instructio
145. e bottom elevation of the cells The Modeling Environment Processing Modflow 3 15 MT3D requires 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 constant concentration Horizontal Hydraulic Conductivity and Transmissivity Horizontal hydraulic conductivity is the hydraulic conductivity along model rows It is multiplied by an anisotropy factor specified in the Layer Options dialog 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 PMWIN uses the horizontal hydraulic conductivity and layer thickness to calculate transmissivity if the corresponding Transmissivity flag in the Layer Options dialog is Calculated You can specify transmissivity of a layer directly by setting the corresponding Transmissivity flag to User specified and choosing Transmissivity from the Parameters menu See section 3 2 2 for more information about the Layer Options dialog Vertical Hydraulic Conductivity and Vertical Leakance For flow simulations involving more than one model layer MODFLOW requires the input of the vertical transmission or leakage term known as vertical leakance VCONT between two model layers PMWIN uses the vertical hydraulic
146. e cell to convert between wet and dry several times during the convergence process but frequent conversions are an indication of problems The user can detect this situation by examining the model run record file 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 As a matter of fact situations exist where the real solution is oscillating such as in the case of a well causing a drawdown which makes the well cell 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 Modeling Environment Processing Modflow 3 29 Wetting Capability BCF2 Iteration Interval for Attemping to Wet Cells 1 7 Cancel Wetting Factor WETFCT 1 Help dda Initial Heads at Rewetted Cells h BOT WETFCT hn BOT C h BOT WETFCT THRESH BOT Bottom of cells THRESH Wetting threshold ie heads at the neighboring cells Fig 3 20 The Wetting Capability BCF2 dialog box Click OK to edit wetting threshold Advection MTADV1 The MT3D model provides four solution schemes for the advection term The user can select a solution scheme in the Advection Package MTADV1 dialog box Fig 3 21 The method of characteristics MOC scheme was implemented in the U S Geological Survey two dimensional transport model Konikow and Bredehoeft 1978 and ha
147. e desired position The sizes of the current column and row are shown on the Statusbar Press the right mouse button once The Grid Editor shows a Size of Column and Row dialog box Fig 3 3 In the dialog box type new values then click OK To insert or delete a column and or a row Click the Assign Value icon Move the grid cursor by using the arrow keys or by clicking the mouse on the desired position 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 To refine a column and or a row Click the Assign Value icon Move the grid cursor by using the arrow keys or by clicking the mouse on the desired position 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 The following table summarizes the use of the Toolbar buttons of the Grid Editor Toolbar Button Action Re l R P E e 2 ial Ss aee i Leave the Grid 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 Zoom Out Forces the Grid Editor to display the entire worksheet Rotate Grid To rotate the model grid click the mouse on the worksheet and hold down the left button while you move t
148. e hydraulic conductivity divided by thickness for the material between the node in that cell and the node in the cell below Because there is not a layer beneath the bottom layer Vcont cannot be specified for the bottom layer is the secondary storage coefficient Read only for layers where LAYCON is 2 or 3 and only if the simulation is transient ISS 0 The secondary storage coefficient is always specific yield is the elevation of the aquifer top Read only for layers where LAYCON is 2 or 3 is a combination of the wetting threshold and a flag to indicate which neighboring cells can cause a cell to become wet If WETDRY lt 0 only the cell below a dry cell can cause the cell to become wet If WETDRY gt 0 the cell below a dry cell and the four horizontally adjacent cells can cause a cell to become wet If WETDRY is 0 the cell cannot be wetted The absolute value of WETDRY is the wetting threshold When the sum of BOT and the absolute value of WETDRY at a dry cell is equaled or exceeded by the head at an adjacent cell the cell is wetted Read only if LAYCON is 1 or 3 and IWDFLG is not 0 Processing Modflow A 17 Well Package Input for the Well Package WEL1 is read from the unit specified in IUNIT 2 FOR EACH SIMULATION 1 Data MXWELL IWELCB Format 110 110 FOR EACH STRESS PERIOD 2 Data ITMP Format 110 3 Data Layer Row Column Q Format 110 110 I10 F10 0 The 3 data normally consists of one record for each well
149. e hydraulic heads in ASCII Matrix format see Appendix 2 gt 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 is disabled if the drawdown file DDOWN DAT is not available PMPATH saves the drawdowns in the ASCII Matrix format see Appendix 2 gt 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 Flow velocities at the center of each cell are saved in the ASCII Matrix format see Appendix 2 In addition the velocity components along the I J and K axes are added to the end of the file The flow velocity at the cell center is the average of the velocities across the six cell faces The default velocity at inactive cells is 1 0x10 gt Particles To save the starting position and the attributes of each particle choose Save Particles As from the File menu and specify a file name in the standard dialog box The following data format is used to save the particles 1 Data version label 2 Data NP 3 Data LI LJ LK I J K Z C 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 spec
150. e required PEST writes some information concerning the optimised parameter set to its run record file PESTCTL REC This file is 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 observation set based on these parameters together with the residuals i e the differences between measured and model calculated observations Then 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 gt Save data for a possible restart If this option is checked PEST will dump the contents of many of its data arrays to a binary file at the beginning of each optimisation iteration this allows PEST to be restarted later if execution is prematurely terminated If subsequent PEST execution is initiated using the r command line switch see Section 5 1 6 of the PEST manual it will recommence execution at the beginning of the iteration during which it was interrupted The Modeling Environment 3 52 Processing Modflow If this option is not checked PEST will not dump its array data at the beginning of each optimisation iteration so that a later recommencement of execution after premature termination is impossible gt Include decimal point even if redundant If this option is not checke
151. e total number of stress periods TUNIT is the name of unit for time such as DAY or HOUR LUNIT is the name of unit for length such as FT or CM MUNIT is the name of unit for mass such as LB or KG These names are used for identification purposes only and do not affect the model outcome Appendix Processing Modflow A 33 TRNOP LAYCON DELR DELC HTOP DZ PRSITY ICBUND SCONC CINACT IFMTCN IFMTNP IFMTRF IFMTDP SAVUCN NPRS TIMPRS is a array that contains logical flags for major transport options TRNOP 1 to 4 corresponds to Advection Dispersion Sink amp Source Mixing and Chemical Reaction Options respectively If any of these options is used enter its corresponding TRNOP element as T otherwise as F TRNOP 5 to 10 are not used in the current version version 1 x of MT3D is the model layer type code Enter one value for each layer Enter LAYCON in as many lines as necessary if NLAY gt 40 If LAYCON 0 the model layer is confined If LAYCON 0 the model layer is either unconfined or convertible between confined and unconfined Note that this corresponds to the LAYCON values of 1 2 and 3 in MODFLOW however there is no need to distinguish between these layer types in the transport simulation is the cell width along rows Enter one value for each column in the grid is the cell width along columns Enter one value for each row in the grid is the top elevation of cells in the firs
152. e 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 23225 m causes a perched ground water body to form in the top two units The total pond leakage is about 2 360 cubic feet per day 66 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 Because of the rectangular symmetry of the system there is no flow between quadrants Therefore only one quarter of the system must be simulated The problem is simulated using a grid of 50 rows 50 columns and 2 model layers A uniform grid spacing of 16 feet is 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 layer 1 simulates the upper geohydrologic unit and is assigned a hydraulic conductivity of 5 feet per day The bottom of layer 1 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 la
153. eaves zone 1 and flows to the second layer The percent discrepancy is calculated by 100 IN OUT IN OUT 2 ee In this example the percent discrepancies of in and outflows for the model and each zone in each layer are acceptably small This means the model equations are correctly solved Water Budget Specify the stress period and time step for which the water budget should be calculated Click Zones to specify subregions When finished click OK to start the calculation Time Stress Period 1 Time Step 1 Cancel Fig 2 9 The Water Budget dialog box PMWBLF SUBREGIONAL WATER BUDGET RUN RECORD FLOWS ARE CONSIDERED IN IF THEY ARE ENTERING A SUBREGION THE UNIT OF THE FLOWS IS L 3 T TIME STEP 1 OF STRESS PERIOD 1 ZONE 1 LAYER 1 FLOW TERM IN OUT IN OUT STORAGE 0 0000000E 00 0 0000000E 00 0 0000000E 00 CONSTANT HEAD 6 2836841E 02 4 4093262E 02 1 8743578E 02 HORIZ EXCHANGE 0 0000000E 00 0 0000000E 00 0 0000000E 00 EXCHANGE UPPER 0 0000000E 00 0 0000000E 00 0 0000000E 00 EXCHANGE LOWER 1 5266858E 04 3 6502272E 04 2 1235413E 04 WELLS 0 0000000E 00 1 8500000E 02 1 8500000E 02 Fig 2 10 Output from the Water Budget Calculator Your First Groundwater Flow Model with PMWIN Processing Modflow DRAINS 0000000E 00 0 0000000E 00 0 0000000E 00 RECHARGE 0000000E 00 0 0000000E 00 0 0000000E 00 ET 0000000E 00 0 0000000E 00 0 0000000E 00 RIVER LE
154. ed from the saturated thickness and hydraulic conductivity The storage coefficient may alternate between confined and unconfined values Vertical flow from above is limited if the aquifer desaturates is a one dimensional array containing an anisotropy factor for each layer It is the ratio of transmissivity or hydraulic conductivity whichever is being used along a column to transmissivity or hydraulic conductivity along a row Set to 1 0 for isotropic conditions 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 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 is the primary storage coefficient Read only for a transient simulation ISS 0 For LAYCON equal to 1 sfl will always be specific yield while for LAYCON equal to 0 2 or 3 sfl will be confined storage coefficient is the transmissivity along rows Tran is multiplied by TRPY to obtain transmissivity along columns Read only for layers where LAYCON is 0 or 2 is the hydraulic conductivity along rows HY is multiplied by TRPY to obtain hydraulic conductivity along columns Read only for layers where LAYCON is 1 or 3 is the elevation of the aquifer bottom Read only for layers where LAYCON is 1 or a is the vertical hydraulic conductivity divided by the thickness from a layer to the layer below The value for a cell is th
155. ed in Input Instructions MXDRN IDRNCB ITMP Layer Row Column Elevation Cond Appendix is the maximum number of drain cells active at one time is a flag and a unit number If IDRNCB gt 0 it is the unit number on which cell by cell flow terms will be recorded whenever ICBCFL see Output Control Options is set If IDRNCB 0 cell by cell flow terms will not be printed or recorded If IDRNCB lt 0 drain leakage for each cell will be printed whenever ICBCFL is set is a flag and a counter If ITMP lt 0 drain data from the last stress period will be reused If ITMP 0 ITMP will be the number of drains active during the current stress period is the is the is the gt layer number of the cell containing the drain row number of the cell containing the drain column number of the cell containing the drain the the elevation of the drain hydraulic conductance of the interface between the aquifer and the drain is is Processing Modflow A 19 River Package Input to the River Package RIV1 is read from the unit specified in IUNIT 4 FOR EACH SIMULATION 1 Data MXRIVR IRIVCB Format I10 I10 FOR EACH STRESS PERIOD 2 Data ITMP Format 110 3 Data Layer Row Column Stage Cond Rbot Format 110 I10 6110 F10 0 F10 0 F10 0 The 3 data normally consists of one record for each river reach If ITMP is negative or zero the 3 data is not read Explanation of Fields Used in Input Instruct
156. ed or even covered by another If you move the mouse cursor into a covered zone the boundary of the zone will not always be highlighted In this case you can move the mouse cursor into the 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 The Modeling Environment Processing Modflow 3 7 Specification of Temporal Data If your model has more than one stress period a Temporal Data dialog box appears after you have clicked the Leave Editor button RE This dialog box allows you to manage your temporal model data You can edit model data for a particular stress period by selecting a row of the table and clicking the Edit Data button If the model data of a stress period are specified the corresponding row of the Data column is marked The Use flag indicates whether the user specified data should be used for the flow simulation or not PMWIN uses the data of the previous stress period if the Use flag is not marked You can click on an appropriate box to mark or unmark the Use flag if the model data have been specified Use Copy Data if you want to copy model data from a stress period to another Temporal Data Edit Data Copy Data ee eee Leave Editor Cancel o Eee The following table summarizes the use of the Toolbar buttons of the Data Editor Toolbar Button Action Leave the Data Editor
157. ed to assign parameters to the model cells To load the Data Editor select a corresponding item from the Grid Parameters Packages or Source menu For example if you want to assign effective porosity to model cells you will choose Effective Porosity from the Parameters menu The Worksheet shows the plan view of a model layer Fig 3 4 An index notation J I K is used to describe the location of cells in terms of columns J rows I and layers K The origin of the cell indexing system is located at the upper top left cell of the model PMWIN numbers the layers from the top down an increment in the K index corresponds to a decrease in elevation You can move to another layer by pressing PgDn or PgUp keys or click the Current Layer edit field in the Toolbar type the new layer number and press Enter The Data Editor provides two display modes Local and Global and two input methods Cell by cell and Zone It also allows you to specify time dependent model data Display Modes In the Local Display mode the model grid is displayed parallel to the Worksheet as shown in Fig 3 4 In the Global Display mode the entire worksheet will be displayed Fig 3 5 Using the Environment Options dialog box see section 3 3 8 you can define the coordinates system and the size of the worksheet You can also place the model grid into a proper position Using the Maps Options dialog box see section 3 3 8 you can import DXF site maps The Cell
158. egarding the order in which is the row number of the cell on one side of the horizontal flow barrier is the column number of the cell on one side of the horizontal flow barrier is the row number of the cell on the other side of the horizontal flow barrier is the column number of the cell on the other side of the horizontal flow barrier is a hydraulic characteristic of the horizontal flow barrier If the layer type is 0 or 2 it is the barrier transmissivity divided by the width thickness of the horizontal flow barrier If the layer type is 1 or 3 it is the barrier hydraulic conductivity divided by the width thickness of the horizontal flow barrier Processing Modflow A 29 Interbed Storage Package Input for the Interbed Storage Package IBS1 is read from the unit specified in IUNIT 19 FOR EACH SIMULATION 1 Data IIBSCB IIBSOC Format I10 I10 2 Data IBQ NLAY Maximum of 80 layers Format 4012 If there are 40 or fewer layers use one record otherwise use two records The following four arrays are needed to specify the material properties and initial compaction of model layers having interbed storage as indicated in the IBQ array The four arrays are first read for the uppermost layer with interbed storage and then continuing downward to lower layers with interbed storage FOR EACH LAYER WITH IBQ CODE GREATER THAN ZERO oh Data HC NCOL NROW Input Module U2DREL 4 Data Sfe NCOL NROW Input Module U2DREL B
159. elatively thin so that instantaneous vertical mixing can be assumed 2 the injection rate is insignificant compared with the ambient uniform flow Comparison of the numerical solutions of MT3D and analytical solutions for two or three dimensional transport can be found in Zheng 1990 This example is the same as that desribed in section 7 2 of the MT3D manual Further examples of MT3D are reconstructed by using PMWIN and are listed in Table 5 2 Fig 5 32 Concentration plume calculated by MT3D Applications and Sample Problems 5 36 Location PMWIN EXAMPLE MT3D1 EX2 PMWIN EXAMPLE MT3D I EX3 PMWIN EXAMPLE MT3D1I EX4 PMWIN EXAMPLE MT3DI EX5 PMWIN EXAMPLE MT3D1 EX6 Processing Modflow Description 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 See section 7 3 of the manual of MT3D for details A numerical model consisting of 31 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 solutio
160. elective use of either MOC or MMOC in the HMOC solution scheme The MOC solution is selected at cells where DCCELL gt DCHMOC The MMOC solution is selected at cells where DCCELL lt DCHMOC Processing Modflow A 37 Chemical Reaction Package Input to the Chemical Reaction Package MTRCT1 is read on unit 5 which is preset in the main program of MT3D The input file is needed only if a sorption isotherm or a first order rate reaction decay or biodegradation is simulated FOR EACH SIMULATION Data ISOTHM IREACT Format I10 I10 Enter 2 4 data if ISOTHM gt 0 pa Data RHOB NLAY Input Module U1DREL one value for each layer Ge Data SP1 NLAY Input Module U1DREL one value for each layer 4 Data SP2 NLAY Input Module U1DREL one value for each layer Enter 5 6 data IREACT gt 0 D Data RC1 NLAY Input Module U1IDREL one value for each layer 6 Data RC2 NLAY Input Module U1DREL one value for each layer Explanation of Fields Used in Input Instructions ISOTHM is a flag indicating whether or if any which sorption type is simulated If ISOTHM 1 Linear isotherm is simulated If ISOTHM 2 Freundlich isotherm is simulated If ISOTHM 3 Langmuir isotherm is simulated If ISOTHM 0 no sorption isotherm is simulated IREACT is a flag indicating whether the first order rate reaction is simulated If IREACI 1 radioactive decay or biodegradation is simulated If IREACI 0 no first order rate rea
161. elements of the correlation coefficient matrix are always unity The off diagonal elements are always between 1 and 1 The closer an off diagonal element is to 1 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 paramters 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 Refer to Anderson and Woessner 1992 for more about the sensitivity analysis 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 equal to 1 125 cfs the river gain equals 11 125 cfs 10 cfs Spreading over the modeled area 1 125ft s recharge ____ ______ _ 15 x 15 S00ft x 500ft 2x10 ft s 5 1 The estimated parameter values are acceptable Applications and Sample Problems 5 6 Processing Modflow 5 3 Estimation of Pumping Rates with PEST Location PMWIN EXAMPLES PEST EX2 Problem Description and Modeling Approach This example involves the encapsulation of a highly contaminated area The parameter e
162. ells where a time variant specified head boundary is selected Flag 0 The specified heads are constant during a time step The CHD1 Package linearly interpolates boundary heads h for each time variant specified head boundary cell by using the equation _PERTIM h h_ h_ h ot gt PERLEN 3 23 where PERTIM is the staring time of a time step in a stress period and PERLEN is the length of the whole stress period Time Variant Specified Head CHD1 Flag i Cancel Start Head L 10 End Head L 9 Current Column 1 Current Row 1 If Flag lt gt 0 the current cell is a Time Variant Specified Head cell Fig 3 19 The Time Variant Specified Head CHD 1 dialog box Wetting Capability BCF2 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 the BCF1 Package of the original MODFLOW McDonald and Harbaugh 1988 except for the wetting and drying of cells In BCF1 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 no flow or inactive cell all conductances to the dry cell are set to zero The cell cannot be wetted again In BCF2 a dry cell or an inactive cell can become wet if the head from the previous iteration in a neighboring cell is greater than or equal to the tu
163. enclosed in parentheses for example 15F5 0 for real data and 15I5 for integer data IPRN is a flag indicating that the array being read should be printed and a code for indicating the format that should be used It is used only if LOCAT is not equal to zero The format codes are different for each of the three modules IPRN is set to zero when the specified value exceeds those defined in the chart below If IPRN is less than zero the array will not be printed IPRN U2DREL U2DINT UI1DREL 0 10G11 4 10111 10G12 5 1 11G10 3 6011 2 9GL346 4012 3 LSE 3013 4 15F7 2 2514 5 LSET 3 2015 6 15F7 4 J 20F5 0 8 20F5 9 20F5 2 10 20FF53 11 20F5 4 12 10G11 4 Appendix A 12 Processing Modflow Basic Package FOR EACH SIMULATION is Data HEADNG 32 Format 20A4 2 Data HEADNG continued Format 12A4 Bs Data NLAY NROW NCOL NPER ITMUNI Format I10 110 110 110 110 4 Data IUNIT 24 Format 2413 BCF2 WEL1 DRN1 RIV1 EVT1 XXXX GHB1 RCH1 SIP1 XXXX SOR1 OC PCG2 STR1 GFD1 HFB1 XXXX XXXX IBS1 CHD1 XXXX LKMT BCF3 BCF1 Note XXXX is reserved underlined packages are not supported by PMWIN Da Data IAPART ISTRT Format I10 I10 6 Data IBOUND NCOL NROW Input Module U2DINT one array for each layer in the grid the Data HNOFLO Format F10 0 8 Data Shead NCOL NROW Input Module U2DREL One array for each layer in the grid NOTE IBOUND and Shead are treated as three dimensional arrays in the pr
164. epresents internal sources and or sinks of water S 1 L is the specific storage of saturated porous media h L is the hydraulic head and t T is time For a three dimensional finite difference cell as shown in Fig 4 3 the finite difference form of equation 1 can be written as Q2 Q x Q2 E Q Q E Qz 7 W i Ah Ay Az Ax Ax Az Ay Ax Ay Az Ax Ay Az At 4 2 where Qy Qa Qy Qyz Qz and Q L T are volume flow rates across the six cell faces Modeling Tools Processing Modflow 4 3 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 over a time interval of length At T 7 fe Q2 Q V y2 toz Z Nyt So My x2 y2 z2 Ay 3 Qy a XS ba Mart ox re vA Z xt y1 z1 y v J Q y v Q X SZ X Fig 4 2 Flow through unit porous medium Fig 4 3 Finite difference approach The left side of equation 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 Equation 4 2 is the mass balance equation for a finite difference cell Substitution of Darcy s law for each flow term in equation 4 2 i e Q Ah K A yields an equation expressed in terms of unknown heads at the center of the
165. equency Predefined Head Values Stress Period For No Flow Cells IE 999 99 Time Step For Dry Cells fa 1E 30 Fig 3 29 The Modflow Output Control dialog box The Modeling Environment 3 42 Processing Modflow For checking 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 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 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 is 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 gt MT3D The MT3D transport model generates an ASCII simulation record file OUTPUT MT3 and an optional unformatted binary concentration file MT3D UCN Both files are saved in the same directory as your model data Optionally you can save some other results in the OUTPUT MT3 file by checking the corresponding output terms in the MT3D Output Control dialog box Fig 3 30 In the dialog box CINACT is the predefined co
166. er initial head is saved these values must be input to initialize the solution is the length of a stress period It is specified for each stress period is the number of time steps in a stress period is the 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 Appendix A 14 Output Control Options Output Control is a major option separate from the rest of the Basic Package Control is read from the unit specified in IUNIT 12 and default output control is used Under the default printed at the end of every stress period Additionally drawdown is printed at the end of every stress period The default printout format for head data are read 0 and drawdown is 10G11 4 the unit number for printer output can be changed to meet the requirements of a necessary All printer output goes to particular computer FOR EACH SIMULATION Tg Data Format IHEDFM IDDNFM IHEDUN IDDNUN I10 TLO I10 I10 FOR EACH TIME STEP 2 Data 3h Data Format Format Record 3 is read 0 INCODE 110 Hdpr 110 THDDFL 110 Ddpr 110 IBUDFL ICBCFL 110 110 Hdsv Ddsv 110 110 1 or NLAY times Explanation of Fields Used in Input Instructions is a code for the format in which heads will be printed is a code for the format in which drawdowns will be printed Format code
167. er rate constant for the dissolved phase 1 T RC2 is the first order rate constant for the sorbed phase 1 T Fig 3 25 The Chemical Reaction Package MTRCT1 dialog box For the Freundlich isotherm the retardation factor at the beginning of each transport step is calculated as P T i i ny where C is the solute concentration in the cell i j k at the beginning of each transport step a is the Freundlich exponent and K L M is the Freundlich constant For the Langmuir isotherm the retardation factor at the beginning of each transport step is calculated as P Ky 5 Map L Ky Capp Rym 1 3 35 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 To simulate the effect of the first order irreversible rate reactions check the box Simulate the radioactive decay or biodegradation in the Chemical Reaction Package MTRCT1 dialog The concentration change due to the chemical reaction from a old transport step to a new transport step at cell i j K can be expressed as Pp ACrer ijk R My Ci ik i Ne Cik 3 36 ijk ijk The Modeling Environment Processing Modflow 3 37 where A T is the first order rate constant for the dissolved phase A T is the first order rate constant for the sorbed phase Atis the transport time step and C j k 18 the mass of the solute species adsorbed on the solids per unit
168. er to extract simulation results from any stress period time step and layer and put them into a spread sheet Users can then view the results or save them in ASCII or SURFER compatible data files Using the Field Generator provided by PMWIN fields with heterogeneously distributed transmissivity or hydraulic conductivity can be generated This allows the user to statistically simulate effects and influences of unknown small scale heterogeneities The Field Generator Frenzel 1995 is based on Mejia s algorithm 1974 PMWIN can display temporal development curves of simulation results including hydraulic heads drawdowns concentrations preconsolidation heads compaction of a model layer and Introduction Processing Modflow 1 3 subsidence of an entire aquifer The Water Budget Calculator for calculating water budgets has been improved It cannot only calculate the budget of user specified zones but also the exchange of flows between zones This facility is very useful in many practical cases It allows the user to determine the flow through a particular boundary exactly e PMWIN comes with the educational version of MT3D and PEST and provides numerous examples including the test problems of the STR1 IBS1 BCF2 and MT3D packages e PMWIN can create contour maps or solid fill plots of input data or simulation results Solid Fill can utilize the full range of RGB colors to fill cells with different values Contours can be added to these
169. ero If the parameter belongs to a group The Modeling Environment 3 54 Processing Modflow 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 Ifa parameter has an initial value of zero the parameter can be neither a tied nor a parent parameter as the tied parent parameter ratio cannot be calculated e PARLBND and PARUBND represent a parameter s lower and upper bounds respectively For adjustable parameters the initial parameter value PARVAL1 must lie between these two bounds However for fixed and tied parameters the values you provide for PARLBND and PARUBND are ignored The upper and lower bounds for a tied parameter are determined by the upper and lower bounds of the parameter to which it is tied and by the ratio between the tied and parent parameters e PARTRANS controls the parameter transformation By clicking on the PARTRANS column this flag can be set as None Log transformed Tied or Fixed Use Log transformed if you wish that a parameter be log transformed throughout the estimation process Logarithmic transformation of some parameters may have a profound affect on the success of the parameter estimation process If a parameter is log transformed PEST optimises the log of the parameter rather than the parameter itself At the end of the parameter estimation process PEST provides the optimised parameter value itself rather than
170. essing Modflow excluding boundary cells 1x10 m storage factors 0 0001 for elastic and 0 001 for inelastic and head decline 5 m under elastic conditions and 5 m under inelastic conditions The correct amount of water released from interbed storage therefore is 5x10 n for declines in the elastic range and 5x10 m for declines in the inelastic range The sum of the two values is consistent with the 5 5x10 m release of water from interbed storage calculated by the model For this example the model computes 5 5x10 m of compaction at the observation point Fig 5 27 That value is consistent with the sum of elastic and inelastic compaction computed from equations 3 18 and 3 19 VOLUMETRIC BUDGET FOR ENTIRE MODEL AT END OF TIME STEP 10 IN STRESS PERIOD 3 CUMULATIVE VOLUMES AAS RATES FOR THIS TIME STEP L 3 T N IN STORAGE 0 20000E 06 STORAGE 0 00000 CONSTANT HEAD 0 59683E 08 CONSTANT HEAD 20000 INTERBED STORAGE 0 55000E 06 INTERBED STORAGE 0 00000 TOTAL IN 0 60433E 08 TOTAL IN 20000 OUT OUT STORAGE 0 00000 STORAGE 0 00000 CONSTANT HEAD 0 60433E 08 CONSTANT HEAD 20000 INTERBED STORAGE 0 00000 INTERBED STORAGE 0 00000 TOTAL OUT 0 60433E 08 TOTAL OUT 20000 IN OUT 4 0000 IN OUT 0 00000 PERCENT DISCREPANCY 0 00 PERCENT DISCREPANCY 0 00 Table 5 1 Volumetric budget at the end of time step 10 in stress period 3 5 5E 3 Compaction in meter 1 52E 3 1 10 100 1000 100
171. esult files are saved in the directory in which your model data are saved e Hydraulic Heads is the primary result of a MODFLOW simulation Hydraulic heads in each finite difference cell are saved in the unformatted binary file HEADS DAT e Drawdowns is 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 e 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 terms which give the rate of accummulation 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 is between adjacent model cells The Water Budget Calculator see Chapter 4 uses the cell by cell flow terms to compute water budgets for the entire model user specified subregions and flows between adjacent subregions PMPATH uses the cell by cell flow terms and the calculated hydraulic heads for calculating and displaying pathlines The cell by cell flow terms are saved in the unformatted binary file BUDGET DAT e Subsidence is the sum of the compaction of all m
172. eters such as transmissivity or porosity only the first value 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 values that are not used must be specified as zero The following table gives the assignment of the parameters in the Value I vector Refer to section 3 3 4 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 X J Y J are the x y coordinates of the J th nodes of the zone The first and the last node must overla
173. etween adjacent model layers divided by the horizontal area of the cell and the effective porosity of the confining unit In PMWIN the effective porosity of the confining unit is assumed to be the same as that of the layer directly above the confining unit The use of the last four layer types is not recommended not only because PMWIN does not allow you to assign effective porosity to the confining units but also they are not supported by PMPATH and MT3D 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 Although the principal axes of the conductivity tensor must be parallel to the I and J axes of your model grid this has been often ignored gt Interbed Storage PMWIN supportes the Interbed Storage Package IBS1 for calculating storage changes from both elastic and inelastic compaction of each model layer Click the flag of a layer and select YES if you want to use the IBS1 package to calculate the compaction of the layer See Packages Menu for more information about the Interbed Storage Package gt Transmissivity MODFLOW requires transmissivity 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 Tr
174. f inner iterations Equation 3 41 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 e 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 is less than or equal to Head Change and the criterion for Residual is satisfied see below iteration stops e Residual L T is the residual criterion for convergence Residual is calcuated 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 e Relaxation Parameter is used with MICCG Usually this parameter is equal to 1 but for some problems a value of 0 99 0 98 or 0 97 will reduce the number of iterations required for convergence e 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 is suppressed Select the option None to
175. f the authors You may not incorporate all or part of the Software into another product for the use of other than yourself without the written permission of the authors Term This Licence is effective until terminated You may terminate it by destroying the Software and documentation and all copies thereof The Licence will also terminate if you fail to comply with any term or condition of the Licence Upon such termination you must destroy all copies of the Software and documentation Disclaimer The user of this software accepts and uses it at his her own risk The authors do not make any expressed of implied warranty of any kind with regard to this software Nor shall the authors be liable for incidental or consequential damages with or arising out of the furnishing use or performance of this software Copyright 1991 1996 Wen Hsing Chiang amp Wolfgang Kinzelbach All Rights Reserved Trademarks Most computer and software brand names have trademarks or registered trademarks The individual trademarks have noto been listed here Table of Contents Preface 1 3 1 3 2 33 3 3 1 3 3 2 3 3 3 3 3 4 3 3 5 3 3 6 3 3 7 3 3 8 3 3 9 4 1 4 1 1 4 1 2 4 1 3 4 1 4 4 2 4 3 4 4 4 5 4 6 Introduction What Is PMWIN New Features in PMWIN System Requirements Setting Up PMWIN Online Help Your First Groundwater Flow Model with PMWIN The Sample Problem Starting PMWIN Run a Steady State Flow Simulation Creat
176. f the injection well Simulation Results The flow field was first calculcated by MODFLOW The hybrid MOC MMOC or HMOC option Applications and Sample Problems Processing Modflow 5 35 was used in the simulation for the advection term with DCHMOC set to 10 and the rest of the parameters as follows DCEPS 10 NPLANE 1 NPL 0 NPH 9 NPMIN 0 NPMAX 16 INTERP 1 NLSINK 1 NPSINK 9 Thus in the solution process the MOC scheme was automatically selected in cells where DCCELL gt 10 and the MMOC scheme was automatically selected in cells where DCCELL lt 10 When the MOC scheme was used 9 particles were placed in cells with a fixed pattern on one vertical plane NPLANE 1 where DCCELL is greater than the specified negligible limit When the MMOC scheme was used 1 fictitious particle was placed at the nodal point for backward tracking except at a sink cell where 9 particles were placed i e NPSINK 9 on one 1 vertical plane within the sink cell block i1 e NLUSINK 1 For particle tracking the fourth order Runge Kutta method is used in the vicinity of the point source whereas the first Euler method is used elsewhere The contour map of the concentration field at the end of the 365 day simulation period obtained for this example is shown in Fig 5 32 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 is r
177. fied and choosing Vertical Leakance from the Parameters menu In the Data Editor VCONTbetween layer i and layer i 1 is given as the data of layer i A VCONTarray is not required for the bottom layer because MODFLOW assumes that the botton layer is underlain by impermeable material and VCONTis zero VCONT 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 dimmed In a confined layer the storage term is given by storativity or confined storage coefficient specific storage L x layer thickness L The specific storage or specific storativity is defined as the volume of water that a unit column of aquifer releases from storage under a unit decline in hydraulic head 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 if the corresponding Storage Coefficient flag in the Layer Options dialog is Calculated By setting the Storage Coefficient flag to User Specified and choosing Storage Coefficient from the Parameters menu you can specify the confined storage coefficient directly In an unconfined layer the storage term is given by specific yield or unconfined storativity Specific yield is defined as the volume of water that an unconfi
178. format in which preconsolidation head will be printed Format codes have the same meaning for subsidence compaction and preconsolidation head and are the same as codes for printing head and drawdown see Output Control Options Appendix A 30 ISUBUN ICOMUN IHCUN ISUBPR ICOMPR IHCPR ISUBSV ICOMSV THCSV Appendix Processing Modflow is the unit number to which subsidence arrays will be written if they are saved on disk is the unit number to which compaction arrays will be written if they are saved on disk is the unit number to which preconsolidation head arrays will be written if they are saved on disk is the output flag for subsidence printout f ISUBPR gt 0 subsidence is printed f ISUBPR lt 0 subsidence is not printed is the output flag for compaction printout f ICOMPR gt 0 compaction is printed for each layer with interbed storage f ICOMPR lt 0 compaction is not printed is the output flag for preconsolidation head printout HCPR gt 0 preconsolidation head is printed for each layer with interbed storage f IHCPR lt 0 preconsolidation head is not printed is the output flag for saving subsidence in an unformatted disk file f ISUBSV gt 0 subsidence is saved f ISUBSV lt 0 subsidence is not saved is the output flag for saving compaction in an unformatted disk file f ICOMSV gt 0 compaction is saved for each layer with interbed storage f ICOMSV lt 0 compaction i
179. g 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 Chiang W H and W Kinzelbach 1993 Processing Modflow PM Pre and postprocessors for the simulation of flow and contaminants transport in groundwater system with MODFLOW MODPATH and MT3D Chiang W H 1994 PMPATH for Windows User s manual Scientific Software Group Washington DC Cooper H H Jr and M I Rorabaugh 1963 Ground water movements and bank storage due to flood stages in surface streams U S Geological Survey Water Supply Paper 1536 J 343 366 Davis J C 1973 Statistics and data analysis in geology John Wiley amp Sons Inc References Processing Modflow 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 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 on Mejia s algorithm Institut fiir Umweltphysik University of Heidelberg Germany Gelhar L W
180. g Format 110 Explanation of Fields Used in Input Instructions MXSTRM is the maximum number of stream reaches that can be active during the simulation NSS is the maximum number of segments that can be used during the simulation NTRIB is the maximum number of tributary segments that can join during a simulation This is the aximum number allowed as currently specified in the program NDIV is a flag which when positive specifies that diversions from segments are to be simulated ICALC is a flag which when positive specifies that stream stages in reaches are to be calculated CONST is a constant value used in calculating stream stage in reaches It is specified whenever ICALC is greater than zero Refer to equation 3 12 for the values of this constant ISTCB1 is a flag and a unit number If ISTCB1 gt 0 it is the unit number to which leakage between each stream reach and the corresponding model cell will be saved on disk whenever the variable ICBCFL is specified See Output Control Options If ISTCB1 0 leakage between each reach and corresponding model cell will not be printed nor filed on disk If ISTCBl lt 0 streamflows into and out of each reach and leakage between each reach and corresponding model cell will be printed whenever the variable ICBCFL is specified ISTCB2 is a flag and unit number for an option of storing streamflow out of each reach instead of having the results printed If ISTCB2 gt 0 it is the unit
181. g Environment 3 58 Processing Modflow gt Prior Information It often happens that we have some information concerning the parameters that we wish to optimise 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 both for the philosophical reason that it is a shame to withhold it and secondly because this information may lend stability to the process To activate a prior information line set the Active flag to YES of the Prior Information table and give the prior information equation in the Prior Information column The syntax of a prior information equation is PIFAC PARNME PIFAC log PARNME PIVAL WEIGHT 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 ie you must not include any fixed or tied parameters in a prior information equation Furthermore any particular parameter can be referenced only once in any one prior information equa
182. g Modflow 4 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 KJ and J I 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 Check simulation results and produce output of chapter 2 for details Modeling Tools Processing Modflow 4 31 4 6 The Graph Viewer To activate the graph viewer
183. g PEST Check the geometrical setting up of the model Help Fig 3 48 The Run PEST dialog box gt Modflow Version Modflow Program and PEST Program You must specify the version of MODFLOW and the full path and file names of MODFLOW and PEST in the Run PEST dialog box Fig 3 48 PMWIN supports four versions of MODFLOW viz User s own and the versions distributed by the Scientific Software Group the International Ground Water Modeling Center and S S Papadopulos amp Associates The User s own version must be used if you are using the MODFLOW provided by PMWIN PMWIN automatically installs MODFLOW in the directory pm_home MODFLOW where pm_home is the home directory of PMWIN Refer to Appendix 5 if you want to use a version of MODFLOW other than the four versions supported by PMWIN There are four variants of PEST They 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 is identical however they each use your machine s memory in a different way PESTLM is 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 The Modeling Environment 3 70 Processing Modflow memory as it calls MODFLOW PESTEM uses your machine s extended memory and execu
184. g a smaller particle tracking step length such that intermediate particle positions between starting point and exit point can be calculated See Particle Tracking Options for how to change the particle tracking step length The Statusbar displays the following messages the current position of the mouse cursor in both x y z coordinates and J I K indices the hydraulic head at the cell J I K the horizontal flow velocity at the center of the cell J I K the vertical flow velocity at the center of the cell J I K the current stress period of the flow simulation the current time step of the flow simulation and the number of particles NANRWNE Modeling Tools Processing Modflow 4 7 See Particle Tracking Options 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 horizontal flow velocity at the center of a cell is the average of the velocities Vy Vyo Vy1 Vo see equation 4 3a 4 3d The vertical flow velocity at the center of a cell is the average of the velocities V V see equation 4 3e and 4 3f The vertical flow velocity is defined as positive when it points in the k direction vertical local coordinate for setting particles current layer top view l K cross section PMPAT 4 EXAMPI E MDL File Run Options Info ___ EPEC KKACEIIELACIE mouse cursor pd
185. g the IUNIT assignments in a corresponding section of PMWIN INI These IUNIT assignments must be the same as those used in the main program of MODFLOW The following two tables show an example Table Al shows a part of the main program of MODFLOW containing the IUNIT assignments Table A2 shows the cooresponding settings saved in the User s own section of PMWIN INI For this example the User s own version of MODFLOW is chosen IF IUNIT 1 GT 0 CALL BCF2AL ISUM LENX LCSC1 LCHY LCBOT LCTOP LCSC2 LCTRPY IUNIT 1 I1SS 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 L IUNIT 2 IOUT I IF IUNIT 3 GT 0 CALL DRN1AL ISUM LENX LCDRAI NDRAIN MXDRN L IUNIT 3 IOUT I IF IUNIT 4 GT 0 CALL RIV1AL ISUM LENX LCRIVR MXRIVR NRIVER UNIT 4 IOUT IRIVCB T 0 CALL EVTIAL ISUM LENX LCIEVT LCEVTR LCEXDP CSURF NCOL NROW NEVTOP IUNIT 5 IOUT IEVTCB T 0 CALL GHB1AL ISUM LENX LCBNDS NBOUND MXBND UNIT 7 IOUT IGHBCB T 0 CALL RCH1AL ISUM LENX LCIRCH LCRECH NRCHOP L COL NROW IUNIT 8 IOUT IRCHCB IF IUNIT 9 GT 0 CALL SIP1AL ISUM LENX LCEL LCFL LCGL LCV L LCHDCG LCLRCH LCW MXITER NPARM NCOL NROW NLAY 2 IUNIT 9 IOUT IF IUNIT 11 GT 0 CALL SOR1AL ISUM LENX LCA LCRES LCHDCG LCLRCH LCIEQP MXITER NCOL NLAY NSLICE MBW IUNIT 11 IOUT IF IUNIT 13 GT 0 CAL
186. g well a Click the Set Particle button b Move the mouse cursor to the model area The mouse cursor becomes a cross hair c Place the cross hair at the upper left corner of the pumping well as shown in Fig 2 22 d Drag the cross hair until the window covers the pumping well Dragging means holding the left mouse button down while you move an object with the mouse e Release the mouse button The Particle Placement dialog box appears Assign the numbers of particles to the edit Your First Groundwater Flow Model with PMWIN Processing Modflow 2 21 fields in the dialog box as shown in Fig 2 23 When finished click OK f To set particles around the pumping well in the second layer press PgDn to move to the second layer and repeat the steps c d and e 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 24 PMPATH allows you to create time related capture zones of pumping wells The 100 days capture zone shown in Fig 2 26 is created by putting particles around the pumping well in the second layer using the settings in the Particle Tracking Options dialog box as shown in Fig 2 25 and clicking Ei Run PMPATH Specify the full path and filename of the PMPATH program When finished click OK to start PMPATH for Windows PMPATH program EAPMWINPMPATH EXE Fig 2 21 The Run PMPATH dialog box
187. ge for a transport solution Each time step is therefore divided into smaller transport steps You can specify the length of transport steps in the table of the Time Parameters dialog box The length of transport steps will be determined by an automatic stepsize control procedure in MT3D if the length of transport steps is 0 zero Recycle Recycle provides a way to create graphics from simulation results You can freely modify the Recycle data in the Data Editor because neither simulation programs nor any parts of PMWIN will use the Recycle data See Chapter 2 for how to produce output graphics Starting Values MODFLOW requires initial hydraulic heads at the beginning of a flow simulation Initial hydraulic heads at constant head cells will be kept constant during the flow simulation The initial hydraulic heads in constant head cells must be higher than the elevation of the bottom of these cells because MODFLOW does not convert dry constant head cells to inactive cells If any constant head cell is dry MODFLOW will stop the flow simulation and write a message CONSTANT HEAD CELL WENT DRY into a run record file see Table 2 1 MODFLOW also requires initial heads in a steady state simulation In that case the intial values are starting values for the iterative equation solvers Note that the heads at the prescribed head cells must be the actual model values while all other initial heads can be set arbitrarily provided they are higher than th
188. ge of error Model calibration can be performed by the hand operated trial and error adjustment of aquifer parameters or by automated calibration programs such as PEST supported by PMWIN MODINV Doherty 1990 or MODFLOW P Hill 1992 This example provides an exercise in model calibration with PEST Specific details of this example are from Andersen 1993 Fig 5 3 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 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 5 1 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 5 2 Initial hydraulic head 100 0 ft grid size 15x 15 Ax Ay 500 ft river base flow at western model boundary 10 cfs river base flow at eatern model boundary 11 125 cfs riverbed conductance 0 01 ft s gt 4 Fig 5 3 Co
189. guage developed by Hewlett Packard These graphics formats can be understood by many graphics or word processing software and graphics devices Using the DXF format you can save and overlay graphics on the Worksheet as you can import DXF files by using the Maps Options To select a format click the down arrow on the Format drop down box You can enter the file name into the File edit field or click and select a file from the standard File Open dialog box Note that PMWIN uses the same resolution as Windows to save bitmap files The 24 bits True Color resolution is not supported by PMWIN Do not try to save graphics in bitmap files if you are using True Color Save Plot As Format px File l e pmwin examples mflowex mflowex dxf Fig 3 8 The Save Plot As dialog box The Modeling Environment 3 10 Processing Modflow 3 3 2 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 a Layer Options dialog box Fig 3 9 The elements of this dialog box are described below Layer Options 1 Unconfined 3 Confined Unconfined Calculated Transmissivity varies 3 Confined Unconfined Calculated Transmissivity varies 3 Confined Unconfined Calculated Transmissivity varies 0 Confined User specified 0 Confined 1 No User specified 0 Confined 1 No User specified
190. h the elevation of the cell top For the water table layers Z is set equal to the head in the cell For the particle tracking water table layers are treated in the same way as variable thickness model layers model grid a EEE ie a L Z 77 22 2222 i T Lf LLLLLLL L T Ze y SIA eee Na D C19 FP LL ett et EE 77 Doy a layer 4 HH LATH Fig 4 5 Discretization with a deformed grid ayer 2 Modeling Tools 4 6 Processing Modflow 4 1 2 PMPATH Modeling Environment The PMPATH modeling environment Fig 4 6 consists of the Toolbar the Top view window of the model Cross section windows of the model and the Status bar They are described below gt Top view window Cross section windows and the Status bar The Top view window shows the plan view of the groundwater model you built in PMWIN PMPATH 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 the cell indexing system is located at the upper top left cell of the model MODFLOW numbers the layers from the top down an increment in the K index corresponds to a decrease in elevation z PMWIN allows a user to shift and rotate a model grid by giving the rotation angle A
191. h as wells recharge or rivers Define data of an iteration solver and output control Source Specify the source concentration which is associated with a specific features of hydrologic system e g concentration of water of an injection well Estimation Specify data for the parameter estimation program PEST Run Call simulation programs modeling tools and postprocessing utilities Value Manipulate model data Read or save model data in separate files Options Modify the appearance of the model grid on the screen Load DXF site maps Help Call the online Help 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 Packages and Source menus will be checked To deactivate a selected item in the Package and Source menu just seleted the item again If you do not know which model data still have to be specified you can try to run your model by selecting the corresponding item from the Run menu PMWIN will tell you what you should do 3 3 1 The File Menu New Model Select New Model to create a new model The New Model dialog is a standard Windows dialog that allows you to choose any available directory or drive on your computer All filenames valid under MS DOS can be used A PMWIN model file uses the extension MDL It is a good idea to save every model in a separate directory where you can keep the model and its output data This wi
192. han that of the aquifer it is automatically set equal to the concentration of the aquifer Note that the location and flow rate of evapotranspiration are obtained from the flow model directly through the unformatted head and flow file MT3D FLO is the number of point sources whose concentrations need to be specified Unspecified point sources are assumed to have a zero concentration by default Note that the concentration of point sinks are always set equal to the concentration of the aquifer JSS are the cell indices layer row column of the point source for which a concentration is to be specified is the specified concentration for the point source at the cell JSS ISS KSS is an integer number indicating the type of the point source as listed below Enter one record for each point source of specified concentration Note that the location and flow rate of point sources sinks are obtained from the flow model directly through the unformatted head and flow file MT3D FLO ITYPE 1 constant head cell ITYPE 2 well ITYPE 3 drain this is defined in MT3D A drain can however never be a source ITYPE 4 river ITYPE 5 general head boundary cell Processing Modflow A 41 Appendix 5 Using PMWIN with your MODFLOW You can configure PMWIN to run with your own MODFLOW by modifying the file PMWIN INI This file is located in the home directory of PMWIN e g C PMWIN PMWIN supports various versions of MODFLOW by usin
193. he derivative approximation as increments are increased is normally much greater for the forward difference method than for any of the central methods particularly the Parabolic option see below Hence the use of one of the central methods with an enhanced derivative increment may allow you to calculate derivatives in an otherwise hostile modeling environment Whenever the central method is employed for derivatives calculation DERINC is multiplied by DERINCMUL no matter whether INCTYP is Absolute Relative or Rel_to_max and whether FORCEN is Always_2 Always_3 or Switch If you do not wish the increment to be increased you must provide DERINCMUL with 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 e DERMTHD There are three variants of the central ie three point method of derivatives calculation each method is described in Section 2 3 1 of the manual of PEST If FORCEN for a particular parameter group is Always_3 or Switch you must inform PEST which three point method to use This is accomplished through the character variable DERMTHD which must be supplied as Parabolic Best_fit or Outside_pts If FORCEN is Always_2 the value of DERMTHD has no bearing on derivatives calculation for the member parameters The Modelin
194. he intersection of a row and column is a cell Each cell of the spreadsheet is corresponding to a model cell in a layer By setting the Save Format option the result can be optionally saved in an ASCII Matrix or a SURFER data file format Follow steps 2 to 6 to save the hydraulic heads of the first and second layers in two ASCII Matrix files H1 DAT and H2 DAT Choose Hydraulic Head from the Result Type drop down box In the Time Layer group type in the Layer edit field For the sample problem the stress period and time step number should be 1 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 Click Save A Save Matrix As dialog box will come up Specify the file name H1 DAT and select a directory in which H1 DAT should be saved Click OK when ready Type 2 in the Layer edit field and repeat steps 4 and 5 to save the hydraulic heads of the second layer in the file H2 DAT Click Close to close the dialog box Your First Groundwater Flow Model with PMWIN Processing Modflow 2 15 Hydraulic Head Hydraulic Head Drawdown Concentration Compaction Preconsolidation Head Subsidence Cell By Cell Flow Terms Results Extractor Result Type Column Width m o slofoloefolofolslols ofso olsolo slofolofolofolo
195. he mouse Shift Grid To shift the model grid click the mouse on the worksheet and hold down the left button while you move the mouse 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 is on if the small box on the lower left corner of this icon is highlighted The Modeling Environment Processing Modflow Model Dimension Layers i Number l 2 as Columns Number l 30 Size l 20 000 Rows Number l 30 Size 20 000 Fig 3 1 The Model Dimension dialog box Processing Modflow BCF2EX1 MDL File Options Help el SKIGEIE worksheet plan view grid cursor position of the mouse curso position of the grid cursor Refinement of column J Refinement of row IT HH mans i j ian ji ii 7555 673 6735 669 5 Mesh Size L 500 width of row width of column J Fig 3 2 The Grid Editor Size of Column and Row Size i Column 500 Cancel Row 500 Her Refinement Column 1 ii Row Number of Columns 21 Number of Rows 20 Current Column 12 Current Row 2 Fig 3 3 The Size of Column and Row dialog box 3 3 The Modeling Environment 3 4 Processing Modflow 3 2 The Data Editor The Data Editor is us
196. he 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 Fig 4 17 Search pattern used by a Quadrant Search Data Per Sector 2 and b Octant Search Data Per Sector 1 Grid Position Using the rotation angle and the coordinates X Yo of the left corner of the model grid you can rotate and place the grid at any position The rotation angle is expressed in degrees and is measured counterclockwise from the positive x direction See section 3 3 8 for details about the coordinate system of PMWIN Modeling Tools Processing Modflow 4 25 GO Click GO to start the interpolation PMDIS 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 automatically opens a DOS box and runs PMDIS BAT in the box The ASCII files are used by the interpolation program Modeling Tools 4 26 Processing Modflow 4 3 The Field Generator PMFGN Using the Field Generator Frenzel 1995 fields with heterogeneously distributed transmissivity or hydraulic conductivity can be gene
197. he unit numbers in IUNIT should be integers from 1 to 99 Although the same number may be used for all or some of the major options it is recommended that a different number be used for each major option Printer output is assigned to unit 6 unless it is changed to meet computer requirements That unit number should not be used for any other input or output The user is also permitted to assign unit numbers for output Those numbers should be different from those assigned to input The Basic Package reads from unit 1 unless it is changed to meet computer requirements It is permissible but unwise to use that unit for other major options UNIT LOCATION Major Option Package Block Centered Flow Package 2 BCF2 2 Well Package WEL1 3 Drain Package DRN1 4 River Package RIV1 5 Evapotranspiration Package EVT1 6 Reserved 7 General Head Boundary Package GHB1 8 Recharge Package RCH1 9 Strongly Implicit Procedure Package SIP1 10 Reserved tt Slice Successive Overrelaxation Package SOR1 12 Output Control Options OC 13 Preconditioned Conjugate Gradient Package 2 Processing Modflow A 13 IAPART ISTRT IBOUND HNOFLO Shead PERLEN NSTP TSMULT 14 Streamflow Routing Package STR1 15 General Finite Difference Flow Package GFD1 Not Supported by PMWIN 16 Horizontal Flow Barrier Package HFB1 17 Reserved 18 Reserved 19 Interbed Storage Package IBS1 20 Time Variant Specified Head Package CHD
198. her programs or you want run an other model saved in the same subdirectory as the current model e Check the geometrical setup of the model PMWIN finds errors in the geometrical setup and writes them to the file CHECK LST if 1 the layer thickness is zero or negative 2 the elevations of the layer top and bottom are not consistent and 3 the starting hydraulic head at a constant head cell is lower than the cell bottom In the last case instead of converting the constant head cell to an inactive dry cell MODFLOW writes an error message to the run record file OUTPUT DAT and stops the simulation e Generate input files only don t start MODFLOW Check this option if you want to run MODFLOW outside of Windows See OK below for details gt OK Click OK to start the generation of input files of MODFLOW In addition PMWIN generates a batch file MODFLOW BAT saved in your model directory After having generated all necessary files PMWIN automatically opens a DOS box and runs MODFLOW BAT in the box Follow the steps below if you want to run MODFLOW outside of Windows 1 In the Run MODFLOW dialog box check the option Generate input files only don t start MODFLOW then click OK 2 Leave Windows 3 Change the default path to your model directory 4 Type MODFLOW BAT at the DOS prompt then press enter During a flow simulation MODFLOW writes a detailed run record to the file OUTPUT DAT saved in your model directory If a flow simulation
199. i e HEADS DAT or DDOWN DAT If it does not correspond to such a time the observation value will be ignored It is PEST s role to minimise the difference residual between the observation value and the corresponding model calculated number by adjusting parameter values until the sum of squared weighted residuals ie the objective function is ata minimum The weight attached to each residual in the calculation of the objective function is given in the Weight column of the observation table An observation weight can be zero if you wish meaning that the observation takes no part in the calculation of the objective function but it must not be negative Refer to the PEST manual for the functionality of weights in the parameter estimation process Bores and Observations Table of Bores OK 250 250 250 350 350 450 Cancel Help uid 1 26 50655 1 27 00705 1 1 60 27 04515 20 57287 20 07482 Save Load i Clear Options Use observed heads for the calibration Use observed drawdowns for the calibration Fig 3 34 The Bores and Observations dialog box The Modeling Environment Processing Modflow PESTEX MDL File Value Options Help 676 3926 441 0828 111 Time independent Transmissivity L 2 T 300
200. ic conductivity Finally you perform the flow simulation by choosing Flow Computation Modflow from the Run menu After the flow simulation is completed 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 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 the sample model A complete reference for all menus and dialog boxes in PMWIN is contained in Chapter 3 The modeling tools are described in Chapter 4 The Sample Problem The configuration of the sample problem is shown in Fig 2 1 The flow domain is bounded by no flow boundaries on the north and south sides The west and east sides are constant head boundaries The hydraulic heads on the west and east boundaries are 9 m and 8 m respectively No Flow Boundary 9 m 8 m Contaminated Area G g Well j Layer 1 600 m Layer 2 Constant Head Boundary h Constant Head Boundary h No Flow Boundary 580 m Fig 2 1 Configuration of the sample problem The aquifer consists of two layers The first layer is unconfined and the second layer is confined Horizontal hydraulic conductivities of the first and second layers are 0 005 m s and 0 001 m s respectively Vertical hydrauli
201. ide of the model Turn Layer Copy on by clicking the Layer Copy icon aa The small box on the lower right corner of this icon will be highlighted 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 by pressing PgDn The cell values of the first layer are copied to the second layer Choose Leave Editor from the File menu or click the Leave Editor icon To specify the horizontal hydraulic conductivity Choose Horizontal Hydraulic Conductivity from the Parameters menu Your First Groundwater Flow Model with PMWIN 2 8 Processing Modflow 2 Choose Matrix gt Reset from the Value menu or press Ctrl R and type 0 005 in the dialog box then click OK 3 Move to the second layer by pressing PgDn 4 Choose Matrix gt Reset from the Value menu or press Ctrl R and type 0 001 in the dialog box then click OK 5 Choose Leave Editor from the File menu or click the Leave Editor icon gt To specify the vertical hydraulic conductivity 1 Choose Vertical Hydraulic Conductivity from the Parameters menu Choose Matrix gt Reset from the Value menu or press Ctrl R and type 0 0005 in the dialog box then click OK 3 Move to the second layer by pressing PgDn 4 Choose Matrix gt Reset from the Value menu or press Ctrl R and type 0 0001 in the dialog box then click OK 5 Choose Leave Editor from the File menu or click the Leave Editor icon
202. ified using local coordinates LJ LI LK Local coordinates vary within a cell from zero to one as shown in Fig 4 12 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 Modeling Tools Fig 4 12 Local coordinates within a cell Modeling Tools Processing Modflow Processing Modflow 4 19 4 2 The Field Interpolator PMDIS 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 i 1 N Where N is the number of measurement points x and y are the coordinates and f is the parameter value at point i One of the basic problems 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 data fitting problems have been proposed Some of the methods are used by commercial contouring software e g GEOKRIG GRIDZO SURFER or TECKON Many modelers and geologists use this software for preparing con
203. imates are poor PEST Control Data Execution Output Options x Write covariance matrix x Write correlation coefficient matrix i Write normalised eigenvector matrix Save data for a possible restart Include decimal point even if redundant Fig 3 32 The PEST Control Data dialog box gt RLAMFAC RLAMFAC a real variable is the factor by which the Marquardt lambda is adjusted RLAMFAC must be greater than 1 0 When PEST reduces lambda it divides by REAMFAC when it increases lambda it multiplies by RLAMFAC PEST reduces lambda if it can However if the normal matrix is not positive definite or if a reduction in lambda does not lower the objective function PEST has no choice but to increase lambda The Modeling Environment 3 46 Processing Modflow gt PHIRATSUF During any one optimisation iteration PEST may calculate a parameter upgrade vector using a number of different Marquardt lambdas First it lowers lambda and if this is unsuccessful in lowering the objective function it then raises lambda If at any stage it calculates an objective function which is a fraction PHIRATSUF or less of the starting objective function for that iteration PEST considers that the goal of the current iteration has been achieved and moves on to the next optimisation iteration Thus PEST will commence iteration i 1 if at any stage during iteration i oO 2 lt PHIRATSUF 3 42 oN where _4is the lowest obje
204. imates 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 Yq 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 Click the Variogram button to display the Variogram dialog box Fig 4 15 You need to select a variogram model from the drop down box and specify the parameters for the selected variogram model PMDIS does not provide a procedure for fitting the selected variogram curve to the measurement data This is a task for geostatistical software 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 Variogram Model Power or Linear Parameters Variance C 6 843471 Nugget Yariance 0 1 Power Factor Slope 1 O Help Cancel OK Fig 4 15 The Variogram dialog box The meaning of necessary parameters and the equations used by the program are listed below Modeling Tools Processing Modflow 4 23 e Power law and linear model Cin 1B P reg gt 0 0 lt T lt 2 4 11 e Logarithmic model ih 3 log h c S0 4 12 e Spherical model 3 hl dal 168 Cvs h lt Cem Oa a 8 4 13 ih
205. ime step in an attempt to solve the system of finite difference equations e 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 e ACCL is the acceleration parameter usually between 1 0 and 2 0 e Head Change 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 Slice Successive Overrelaxation SSOR Allowed Iteration Number MXITER 50 Printout From the Solver Interval IPRSOR 1 Acceleration Parameter ACCL 1 Convergence Criterion Head Change L 0001 Fig 3 27 The Slice Successive Overrelaxation SSOR dialog box gt PCG2 PCG2 provides two preconditioning options the modified incomplete Cholesky preconditioner MICCG Axelsson and Lindskog 1986 and the least squares polynomial preconditioner POLCG Saad 1985 You can select a preconditioning method in the Preconditioned Conjugate Gradient 2 dialog box as shown in Fig 3 28 The required parameters are described below Preconditioned Conjugate Gradient 2 Preconditioned Conjugate Gradient 2 Precondit
206. imited or factor limited depends on the parameter However you should note that a parameter can be reduced from its current value right down to zero for a relative change of only 1 If you wish to limit the extent of its downward movement during any one iteration to less than this you may wish to set RELPARMAX to for example 0 5 however this may unduly restrict its upward movement It may be better to declare the parameter as factor limited If so a FACPARMAX value of say 5 0 would limit its downward movement on any one iteration to 0 2 of its value at the start of the iteration and its upward movement to 5 times its starting value This may be a more sensible approach for many parameters It is important to note that a factor limit will not allow a parameter to change sign Hence if a parameter must be free to change sign in the course of the optimisation process it must be relative limited furthermore RELPARMAX must be set at greater than unity or the change of sign will be impossible Thus the utility program PESTCHEK see section 3 3 9 will not allow you to declare a parameter as factor limited or as relative limited with the relative limit of less than 1 if its upper and lower bounds are of opposite sign Similarly if a parameter s upper or lower bound is zero it cannot be factor limited and RELPARMAX must be at least unity Suitable values for RELPARMAX and FACPARMAX can vary enormously between cases For highly non linear problems the
207. ing 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 River RIV1 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 Data Editor to assign the following three values to the model cells Hydraulic conductance of the riverbed CRIV L T Head in the river HAIV L and Elevation of the bottom of the riverbed RBOT L The Modeling Environment Processing Modflow 3 19 The values CRIV HRIV and RBOTof a river cell are shown from left to right on the Statusbar For transient flow simulations involving several stress periods these values can be different from period to period If the hydraulic head h in a river cell is greater than RBOT the rate of leakage QRIV from the river to the aquifer is calculated by QRIV CRIV HRIV h h gt RBOT 3 9 For the case that h is greater than HAIV QRIV 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 QRIV CRIV HRIV RBOT h lt RBOT 3 10 The value CRIV of a river cell is often given by criv KEW 3 11 where the value K is the hydraulic conductivity of the rive
208. ing the parameter estimation process PEST prints the optimised parameter values to the run record file PESTCTL REC saved in your model directory PEST automatically writes the optimised 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 You can use the modeling tools to examine the results Note that you should assign the optimised parameter values to your model by using the Data Editor because PMWIN does not retrieve these values automatically Flow Computation MODFLOW gt Modflow Version and Modflow Program You must specify the version of MODFLOW and the full path and file name of MODFLOW in the Run Modflow dialog box Fig 3 49 PMWIN supports four versions of MODFLOW viz User s own and the versions distributed by the Scientific Software Group the International Ground Water Modeling Center and S S Papadopulos amp Associates The User s own version must be used if you are using the MODFLOW provided by PMWIN PMWIN automatically installs MODFLOW in the directory pm_home MODFLOW where pm_home is the home directory of PMWIN Refer to Appendix 5 if you want to use a version of MODFLOW other than the four versions supported by PMWIN Run Modflow Modflow Version User s own Modflow Program e pmwin modflow modflow exe Basic Package e pmwin examples sample bas dat Block Centered Flow BCF1 2 e pmwin
209. ion 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 ENTER FILE NAME lt CR gt 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 by 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 path MPATH30 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 t
210. ion to the top face of cells Treat evapotranspiration as a distributed sink Fig 4 10 The Particle Tracking Options dialog box e Time Mark PMPATH places time marks on pathlines for each n th tracking step where n is the appearance frequence of the time marks given in Interval Check the corresponding Visible check boxes if you want to see time marks on the top view or the cross section windows The appearance 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 size can range from 1 to 2 147 483 647 e Simulation 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 that flowlines change in each time step of a transient flow simulation the flowlines and pathlines do not coincide Use the option Pathlines use transient flow fields to calculate transient pathlines e Stop Condition In general particles will stop when the
211. ioning Method Preconditioning Method Modified Incomplete Cholesky Modified Incomplete Cholesky Neuman Series Polynomial Neuman Series Polynomial Relaxation Parameter 1 e Calculate the upper bound on the maximum eigenvalue Allowed Iteration Numbers Convergence Criteria Allowed Iteration Numbers 1 Convergence Criteria Outer Iteration MXITER Head Change L Outer Iteration MXITER Head Change L 20 0001 20 0001 Inner Iteration ITER1 Residual L 3 T Inner Iteration ITER1 Residual L 3 T 20 0001 20 0001 Printout From the Solver All available information Printout From the Solver All available information O The number of iterations only The number of iterations only O None None Printout Interval fi Help Printout Interval 1 Fig 3 28 The Preconditioned Conjugate Gradient 2 dialog box OK Cancel ul gai The Modeling Environment 3 40 Processing Modflow e MXITER is the maximum number of outer iterations For each outer iteration A and b equation 3 41 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 e ITERI is the maximum number o
212. ions MXRIVR IRIVCB ITMP Layer Row Column Stage Cond Rbot is the maximum number of river reaches active at one time is a flag and a unit number If IRIVCB gt 0 it is the unit number on which cell by cell flow terms will be recorded whenever ICBCFL see Output Control Options is set If IRIVCB 0 cell by cell flow terms will not be printed or recorded If IRIVCB lt 0 river leakage for each reach will be printed whenever ICBCFL is set is a flag and a counter If ITMP lt 0 river data from the last stress period will be reused If ITMP gt 0 ITMP will be the number of reaches active during the current stress period is the layer number of the cell containing the river reach is the row number of the cell containing the river reach is the column number of the cell containing the river reach is the head in the river is the riverbed hydraulic conductance is the elevation of the bottom of the riverbed Appendix A 20 Processing Modflow Evapotranspiration Package Input to the Evapotranspiration Package EVT1 is read from the unit specified in IUNIT 5 FOR EACH SIMULATION 14 Data NEVTOP IEVTCB Format I10 110 FOR EACH STRESS PERIOD 23 Data INSURF INEVTIR INEXDP INIEVT Format 110 110 110 I10 Bi Data SURF NCOL NROW Input Module U2DREL 4 Data EVTR NCOL NROW Input Module U2DREL 5 Data EXDP NCOL NROW Input Module U2DREL IF NEVTOP IS EQUAL TO TWO 6 Data IEV
213. ions it will terminate execution NPHINORED is an integer variable a value of 3 is often suitable gt RELPARSTP and NRELPAR If the magnitude of the maximum relative parameter change between optimisation iterations is less than RELPARSTP over NRELPAR successive iterations PEST will cease execution The relative parameter change between optimisation iterations for any parameter is calculated using equation 3 44 PEST evaluates this change for all adjustable parameters at the end of each optimisation iteration and determines the relative parameter change with the highest magnitude If this maximum relative change is less than RELPARSTP a counter is advanced by one if it is greater than RELPARSTP the counter is zeroed All adjustable parameters whether they are relative limited or factor limited are involved in the calculation of the maximum relative parameter change RELPARSTP is a real variable for which a value of 0 01 is often suitable NRELPAR is an integer variable a value of 2 or 3 is normally satisfactory The Excution Output Options of the PEST Control Data dialog box are described below gt Write covariance matrix write correlation coefficient matrix and write normalised eigenvector matrix After the optimisation process is 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 ar
214. ior to another model run In some cases it may be desirable to increase the value of the increment for this process over that used for forward difference derivatives calculation The real variable DERINCMUL allows you to achieve this If three point derivatives calculation is employed the value of DERINC is multiplied by DERINCMUL this applies whether DERINC holds the increment factor as it does for Relative or Rel_to_max increment types or holds the parameter increment itself as it does for Absolute increment types For many models the relationship between observations and parameters while being in theory continuously differentiable is often granular when examined under the microscope this granularity being a by product of the numerical solution scheme used by the model In such cases the use of parameter increments which are too small may lead to highly inaccurate derivatives calculation especially if the two or three sets of parameter observation pairs used in a particular derivative calculation are on the same side of a bump in the parameter observation relationship Parameter increments must be chosen large enough to cope with model output granularity of this type But increasing parameter increments beyond a certain amount diminishes the extent to which finite differences can approximate derivatives the definition of the derivative being the limit of the finite difference as the increment approaches zero However the deterioration in t
215. ironment Processing Modflow 3 21 Streamflow Routing Package STR1 Segment Reach E 1 Steam _ Streambed Properties Stream Channel Properties Streamflow L 3 T Hydraulic Conductance L 2 T Stream Width L 4 5 1 2 10 Stream Stage L Elevation of the Streambed Top Stream Slope 495 492 007 Elevation of the Streambed Bottom Manning s roughness coeff C 490 0202 Options Current Column 3 x Simulate diversions from segments Current Row 1 i Calculate stream stages in reaches Stream Structure ee ao Fig 3 13 The eee Pe a T T box segment 1 segment 4 segment 3 segment 5 Fig 3 14 The configuration of the stream system specified in the table of figure 3 13 Similar to the River Package leakage Q to or from the aquifer through the streambed is computed by Darcy s Law as follows Q CSTR H h h gt SBOT Q CSTR H SBOT h lt SBOT 3 13 where CSTR is the hydraulic conductance of the streambed H is the head in the stream h is the head in the model cell beneath the streambed and SBOT is the elevation of the bottom of the stream The Modeling Environment 3 22 Processing Modflow 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 Q n C w S4 d 3 14
216. is successfully complete 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 Output Control gt Modflow from the Packages menu Pathline and Contours PMPATH To run PMPATH specify the path and file name in to the Run PMPATH dialog box Fig 3 50 and click OK Normally you do not need to change the default path and file name displayed in this dialog as PMWIN will install PMPATH in its home directory However if you have changed the configuration of your computer for example added a new hard drive you may need to change the path The Modeling Environment Processing Modflow 3 73 PMPATH runs independently from PMWIN If you have subsequently modified model data and performed the flow computation you must load the modified model into PMPATH again to ensure that PMPATH can recognize the modifications Run PMPATH Specify the full path and filename of the PMPATH program When finished click OK to start PMPATH for Windows PMPATH program 4 pmwin pmpath exe Fig 3 50 The Run PMPATH dialog box Solute Transport MT3D gt MT3D Program PMWIN needs to know the full path and file name of MT3D You can type the full path and file name of MT3D in the Run MT3D dialog box Fig 3 51 or click and select the MT3D program from the standard Open file dialog box
217. is the minimum concentration in the entire grid With the dynamic approach the user defines a criterion DCEPS the higher number of particles NPH is placed in cells where the relative concentration gradient is greater than DCEPS and the lower number of particles NPL in cells where the relative concentration gradient is less than DCEPS In many practical problems involving solute transport modeling the contaminant plumes may occupy only a small fraction of the finite difference grid and the concentrations may be changing rapidly only at sharp fronts In these cases the number of total particles used is much smaller than required The Modeling Environment 3 30 Processing Modflow in the uniform particle distribution approach thereby the efficiency of the method of characteristics model can be increased with little loss in accuracy Advection Package MTADV1 Solution Scheme Method of characteristics MOC Modified method of characteristics MMOC Hybrid MOC MMOC HMOC Cancel O Upstream finite difference method Particle Tracking Algorithm O First order Euler algorithm Fourth order Runge Kutta algorithm Use Runge Kutta algorithm in sink source cells and the cells next to sinks sources cells otherwise use Euler algorithm Particle Placement Movement Max number of total moving particles MXPART Courant number PERCEL Concentration weighting factor WD Negligible re
218. ition An IBOUND array is required by flow models The IBOUND array contains a code for each model cell which indicates whether 1 the hydraulic head is computed active variable head cell or active cell 2 the hydraulic head is kept fixed at a given value constant head cell or time varying specified head cell or 3 no flow takes place within the cell inactive cell It is suggested to use 1 for an active cell 1 for a constant head cell and O for an inactive cell For constant head cells the initial hydraulic head remains the same throughout the simulation The initial hydraulic head is specified by choosing Starting Values gt Hydraulic Heads from the Parameters menu A constant head boundary exists whenever the aquifer is in direct hydraulic contact with a river a lake or a reservoir in which the water level is known It is important to know that a specified head boundary provides inexhaustible supply of water The groundwater system may get as much water as it needs from the constant head boundary In some situations this may be unrealistic You should thus be careful in setting constant head boundaries Consider to use the General Head Boundary GHB1 or the Time Variant Specified Head CHD1 packages if the head at the prescribed head boundary varies with the time An ICBUND array is required by transport models The ICBUND array contains a code for each model cell which indicates whether 1 the concentration varies with time active co
219. ity will be in units of ft All model data are specified in the Data Editor see below or dialog boxes PMWIN saves the model data in binary files A list of the binary data files is given in Appendix 2 Prior to running the supported models MODFLOW MT3D or MODPATH or the parameter estimation program PEST PMWIN will generate the required ASCII input files The file names of the ASCII input files are given in Appendix 7 The formats of the input files of MODFLOW and MT3D are given in Appendices 3 and 4 The particle tracking model PMPATH retrieves the binary data files directly thus no ASCII input file is required by PMPATH PMWIN uses pull down menus All modeling operations are controlled from the menu A Toolbar is displayed below the menu and contains icons that represent available PMWIN operations or commands Using the Toolbar is a shortcut to the menu system To execute one of these shortcuts use the mouse to move the cursor over the toolbar icon and click on the Toolbar button In the following sections the use of the Grid Editor the Data Editor and each menu will be described in detail Some of this information has already been given in Chapter 2 however chapter 3 is a complete reference of all menus and dialogs in PMWIN 3 1 The Grid Editor 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 1 will ask you for the basic size of the model grid Afte
220. l be printed or saved at every transport step in the default observation point file MT3D OBS IOBS and JOBS are the cell indices layer row column in which the observation point or monitoring well is located and for which the concentration is to be printed or saved at every transport step in file MT3D OBS Enter one set of KOBS IOBS JOBS for each observation point is a logical flag indicating whether a one line summary of mass balance information for each transport step should be saved in the default file named MT3D MAS for checking purposes f CHKMAS T the mass balance information for each transport step will be saved n file MT3D MAS f CHKMAS F file MT3D MAS is not created s the length of the current stress period s the number of time steps in the current stress period s the multiplier for the length of successive time steps f TSMULT gt 0 the length of each time step within the current stress period is alculated using the geometric progression as in MODFLOW Note that PERLEN NSTP and TSMULT must be the same as those used in the flow model except in steady state simulations f TSMULT lt 0 the length of time steps within the current stress period is read Qa ae ae haa aha LE from the 22 Data This option is needed in case the length of time steps in the head solution is not based on a geometric progression in a flow model other than MODFLOW provides the length of time steps in the current stress period This rec
221. l in the Evapotranspiration EVT1 dialog box Fig 3 16 Maximum ET Rate Repy LT Elevation of the ET Surface h L ET Extinction Depth d L and Layer Indicator The specified values will be shown on the Statusbar Note that although the values are specified for each vertical column of cells you are allowed to move to other layers within the Data Editor and examine the grid configuration in each layer Evapotranspiration EVT1 Maximum ET Rate L T 5E 1 0 Elevation of the ET Surface L fi 2 Cancel ET Extinction Depth L Booo Layer Indicator IEVT gt b Evapotranspiration Options ET is calculated on for cells in the top grid layer Vertical distribution of evapotranspiration is specified in IEVT Current Column 16 Current Row 11 The evapotranspiration option is applied to the entire matrix IEVT is only required if the second evapotranspiration option is selected Fig 3 16 The Evapotranspiration EVT1 dialog box The EVT1 Package is 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 Rerum 2 No evapotranspiration 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 The Modeling
222. l results are usually uncertain due to the imperfect knowledge of aquifer parameters We are uncertain about whether the calibrated values of parameters indeed 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 consider the uncertainty In the stochastic modeling the model parameters appear in the form of probability distributions of values rather than as deterministic sets This example illustrates a conception of stochastic modeling We use the same model as described in chapter 2 and utilize the Field Generator to create a lognormal correlated distribution of the horizontal hydraulic conductivity The mean value of the horizontal hydraulic conductivity is assumed to be u log K 2 3 and the standard deviation o 0 5 The correlation length is 60m 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 realisations of the heterogeneous distribution of hydraulic conductivity are introduced it is obvious that the capture zone not always covers the entire contaminated area Define the safety criterion as the percentage of the covered area in relation to the entire contaminated area To estimate this safety criterion a stochastic simulation should be performed Simulation Results Using
223. lacement of boundaries In practice you can specify the real observation time and data in that dialog box and use PEST to estimate the aquifer transmissivity In this sample model the aquifer transmissivity is already defined as an estimated parameter see Parameter List of section 3 3 6 for details Click RUN gt Parameter Estimation PEST to see how PEST works Refer to Freeze and Cherry 1979 for more information on the Theis solution and the pumping test Drawdown ee ee ee ee eee ee ey Sesbocclcn she gee cl acckucchicccibccekeu ot Pp Sa pes sp sap Saas a Siem ae Samp RS Reiss sy jeneee analytical calculated iS ee Sale a cline Seine a aaa aaa ee E te cee Time OE 0 8 64E 4 Fig 5 2 Drawdown versus time curves Applications and Sample Problems Processing Modflow 5 3 5 2 Model Calibration with PEST Location PMWIN EXAMPLES PEST EX1 Problem Description and Modeling Approach 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 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 ran
224. late 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 See en ee ne ee el 51 ee eee ee ae 50 wegen en ee eH ee es I 1 I 1 1 49 48 weeede eww eb ewe dew ew ele eee be we ole ww eb eww ew de ew ew I Stream stage in feet above sea le 47 46 0 10 20 30 40 50 60 70 80 90 Times in days since start of flood Fig 5 24 Model calculated river stage The ground water flow model with the Streamflow Routing Package has an advantage over analytical solutions because it can be used to simulate complex systems The example Location PMWIN EXAMPLES STRI EX3 of a stream system shown in Fig 5 25 is used to illustrate most of the features of the STR1 package The example assumes an aquifer 6 000 ft wide by 6 000 ft long 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 as does discharge from the aquifer The example includes 7 stream segments with a total of 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 re
225. lative concentration gradient DCEPS Pattern for initial placement of particles NPLANE 2 Fig 3 21 The Advection Package MTADV1 dialog box The modified method of characteristics MMOC uses one particle for each finite difference cell 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 average concentration at the cell where the particle is placed The MMOC technique in the MT3D model is intented for use in situations where sharp fronts are not present so that any numerical dispersion error resulting from the solution scheme is insignificant 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 is automatic adaptation of the solution process to the nature of the concentration field When sharp concentration fronts are present the advection term is solved by MOC through the use of moving particles dynamically distributed around each front Away from such fronts the advection term is solved by MMOC The criterion DCHMOC for controlling the switch between the MOC and MMOC schemes is given by the user If DCCELL gt DCHMOC then the MOC scheme i
226. lity of the BCF2 Package to handle a broad range of possibilities for cells converting between wet and dry in the top aquifer When solving for natural conditions the top aquifer initially is specified as being entirely dry and many cells must convert to wet When solving for pumping conditions the top aquifer is initially specified to be under natural conditions and many cells must convert to dry 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 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 Applications and Sample Problems Processing Modflow 5 15 1507 areal recharge Conceptual Model 0 004 ft d Potentiometric surface 100 Upper aquifer Confining unit Lower aquifer Cross sectional model configuration Layer 1 Hydraulic conductivity 10 feet per day 50 7 I 7 44 III OF IVA _ Confining unit Vertical Leakance 0 001 per day 0 LM L 4 hk FS hk Layer 2 Transmissivity 500 feet sequared per day Elevation in feet above arbitrary datum
227. ll also allow you to run several models simultaneously multitasking If a desired directory is not available you need to use the File Manager of Windows or other utilities to create the directory Open Model Use Open Model to load an existing PM model Models created by using PM3 0x are compatible to PMWIN Once a model is opened PMWIN shows the file name of the model on the Title Bar The Modeling Environment Processing Modflow 3 9 Model Information Open the Model Information dialog box as shown in Fig 3 7 This dialog provides brief information about your model You can type a simulation title into the dialog The maximum length of the simulation title is 132 characters Model Information Simulation Title manual of Modflow Chapter A1 Book 6 USGS Open File Report 83 875 About This Model Model e pmwin examples mflowex mflowex mdl Number of Rows 15 Number of Columns 15 Simulation Time Unit seconds Fig 3 7 The Model Information dialog box Save Plot As Use Save Plot As to save the contents of the worksheet in graphics files Fig 3 8 Save Plot As can only be used within the Local Display mode of the Data Editor Three graphics formats are available Drawing Interchange File DXF Hewlett Packard Graphics Language HP GL and Windows Bitmap BMP DXF is a fairly standard format developed by Autodesk for exchanging data between CAD systems HP GL is a two letter mnemonic graphics lan
228. lock b Random pattern 8 particles are placed randomly within the cell block Fixed pattern 1 Fixed pattern 4 Fixed pattern 2 Fixed pattern 3 Fixed pattern 5 Fixed pattern 6 Fig 3 23 Distribution of initial particles using the fixed pattern after 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 is then rounded to one of the numbers of particles shown here The Modeling Environment 3 34 Processing Modflow Dispersion MTDSP1 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 MT3D The transport step size cannot exceed an upper limit MT3D uses the following stepsize criterion 0 5 R Dy Di Di 3 30 Ax Ay Az At lt where Ax Ay and Az are the widths of the cell in the x y and z directions R is the retardation factor Do Dy and D are calculated as I I v v v vV T L Daonst o o D vy y gS g lvl gt x Iyl Se iyl I I v v v V dhs D__ ay Ge Oy D 3 31 y R RS ue lvl gt x Iyl Se iyl I I v v V T D y g Oy D y RS RS L lvl Se Iyl Se iyl wher
229. log box Interbed Storage IBS1 For steady state flow simulations the menu Interbed Storage IBS1 is not used and dimmed The Interbed Storage Package Leake and Prudic 1991 simulates elastic and inelastic compaction of compressible fine grained beds due to groundwater extraction The term interbed is used to denote a poorly permeable bed within a relatively permeable aquifer To incorporate the calculation of interbed storage of a layer set the Interbed Storage flag to YES see Layer Options dialog in section 3 3 2 The data required by the IBS1 Package are specified by using the Data Editor in the Interbed Storage dialog box Fig 3 18 Preconsolidation Head or preconsolidation stress H L in terms of head in the aquifer Preconsolidation head is the previous minimum head value in the aquifer For any model cells in which the specified preconsolidation head is greater than the corresponding value of initial head the value of the preconsolidation head will be set to that of the initial head Elastic Storage Factor S 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 IBS1 Package are added to Starting Compaction so that stored values of compaction and land subsidence may include previous components Starting Compaction does not affect calculations of storage changes or resulting compaction Interbed
230. lumetric budget will always be printed at the end of a even if the value of IB UDFL is zero are not saved or printed are printed or recorded on disk depending packages i e IWELCB IRCHCB etc he corresponding layer he corresponding layer is not saved for the corresponding layer is saved for the corresponding layer drawdown is not saved for the corresponding layer drawdown is saved for the corresponding layer Processing Modflow A 15 Block Centered Flow 2 Package Most of the data required by the BCF2 Package are the same as for the BCF1 Package These data consist primarily of arrays that are used to calculate conductance and storage terms for each layer The required arrays can include transmissivity hydraulic conductivity specific yield confined storage coefficient vertical leakance aquifer bottom elevation and aquifer top elevation The specific arrays required depend on the options that are used as indicated by the layer type code LAYCON The reader is referred to section 3 3 2 for a detailed description of these data Because BCF2 is designed as a replacement for BCF1 input unit number is specified in IUNIT 1 The data are read once at the start of the simulation FOR EACH SIMULATION 1 Data ISS IBCFCB HDRY IWDFLG WETFCT IWETIT IHDWET Format I10 110 F10 0 110 F10 0 I10 I10 Zee Data LAYCON NLAY Maximum of 80 layers Format 4012 If there are 40 or fewer layers use one record otherwise use
231. ly erase particles located in the current layer The current layer is shown in the toolbar of the PMPATH modeling environment Fig 4 6 Change it first if you need to erase particles in another layer Modeling Tools Processing Modflow 4 11 gt To delete particles 1 Click the Erase particle icon x 2 Move the mouse cursor to where you want a corner of the Erase window 3 Drag the mouse cursor until the window covers the particles which will be deleted 4 Release the mouse button Zoom In By default PMPATH displays the entire model grid Zoom in is useful if you want to see 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 Save Graphics for how to save plots gt To zoom in on a part of the model 1 Click the Zoom In icon 2 Move the mouse cursor to where you want a corner of the Zoom window 3 Drag the mouse cursor until the window covers the model area which is to be displayed 4 Release the mouse button Zoom Out Clicking on the Zoom out button forces PMPATH to display the entire model grid Particle color Clicking on the Particle color button allows a user to select a color for new particles from a standard 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 are placed within or on the cell faces of each
232. maximum factor change that a parameter is allowed to undergo Any particular parameter can be subject to only one of these constraints i e a particular parameter must be either relative limited or factor limited in its adjustments Parameters are denoted as either relative limited or factor limited through the variable PARCHGLIM supplied for each parameter in the Parameter List see below The relative change in parameter b between optimisation iterations i l and i is defined as bon 7 b b on 3 44 The Modeling Environment 3 48 Processing Modflow If parameter b is relative limited the absolute value of this relative change must be less than RELPARMAX If a parameter upgrade vector is calculated such that the relative adjustment for one or more relative limited parameters is greater than RELPARMAX the magnitude of the upgrade vector is reduced such that this no longer occurs The factor change for parameter b between optimisation iterations i l and i is defined as bl Dy if Ib g gt lb or bbo if Ib gt Ib d 3 45 If parameter b is factor limited this factor change which either equals or exceeds unity according to equation 3 45 must be less than FACPARMAX If a parameter upgrade vector is calculated such that the factor adjustment for one or more factor limited parameters is greater than FACPARMAX the magnitude of the upgrade vector is reduced such that this no longer occurs Whether a parameter should be relative l
233. ment 3 38 Processing Modflow where A is a coefficient matrix assembled by MODFLOW using user specified model data b is a vector of defined flows terms associated with head dependent boundary conditions and storage terms at each cell x is a vector of hydraulic heads at each cell In MODFLOW one value of head for each cell is computed for the end of each time step PMWIN supports three packages solvers for solving systems of simultaneous linear equations by iteration They are the Strongly Implicit Procedure SIP the Slice Successive Overrelaxation approach SSOR and the Preconditioned Conjugate Gradient 2 method PCG2 Input parameters of these solution methods are discussed below See McDonald and Harbaugh 1988 and Hill 1990a for detailed mathematical background and numerical implementation of these solvers Various comparisons between the solution methods can be found in Trescott 1977 Behie et al 1983 Scandrett 1989 and Hill 1990b Hill indicates that the greatest differences in solver efficiency on scalar computers occurs 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 SIP generally is a good alternative to consider gt SIP You specify the required parameters in the Strongly Implicit Procedure SIP dialog box Fig 3 26 The parameters are described below e MXITER is the maximum number of iterations in one time
234. mental observations is reduced to a minimum This sum is referred to as the objective function Control Data You specify the control data and excution output options in the PEST Control Data dialog box Fig 3 32 The data are used to set internal array dimensions of PEST tune the optimisation algorithm to the problem at hand and set some data output options The user can refer to the manual of PEST for detailed information about the PEST algorithm The items of the control data are described in details below When in doubt you should use the default values given by PMWIN gt RLAMBDA1 This real variable is the initial Marquardt lambda see section 2 1 7 of the manual of PEST PEST attempts parameter improvement using a number of different Marquardt lambdas during any one optimisation iteration however 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 optimisation While the latter method is inefficient and slow if used for the entirety of the optimisation process it often helps in getting the process started especially if initial parameter est
235. mulation Note that a constant head cell May or may not be a constant concentration cell If ICBUND gt 0 the cell is a variable active concentration cell is the starang concentration at the beginning of the simulation is the value for indicating an inactive concentration cell ICBUND 0 Even if it is not anticipated to have inactive cells in the model a value for CINACT still must be submitted is a flag indicating whether the calculated concentration should be printed and also serves as a printing format code if it is printed The codes for print formats are the same as those for the input module see Appendix A3 If IFMTCN gt 0 concentration is printed in the wrap form If IFMTCN lt 0 concentration is printed in the strip form If IFMTCN 0 concentration is not printed is a flag indicating whether the number of particles in each cell should be printed and also serves as a printing format code if they are printed The convention is the same as that used for IFMTCN is a flag indicating whether the model calculated retardation factor should be printed and also serves as a printing format code if it is printed The convention is the same as that used for IFMTCN is a flag indicating whether the model calculated distance weighted dispersion coefficient should be printed and also serves as a printing format code if it is printed The convention is the same as that usedfor IFMTCN is a logical flag indicating whether the conce
236. n reactions and first order irreversible rate reactions such as radioactive decay or biodegradation You can select a sorption type in the Chemical Reaction Package MTRCT1 dialog box Fig 3 25 and specify the necessary data for each layer in the table Sorption is implemented in MT3D through use of the retardation factor R For the linear isotherm the retardation factor is independent of the concentration field and is calculated only once for each cell in the beginning of the simulation p Nan Ryp 1 K_ 3 33 where n jx is the porosity of the porous medium in cell i j k Ky L M is the distribution coefficient that depends on the solute species nature of the porous medium and other conditions of the system and p ML is the bulk density of the porous medium The bulk density is the ratio of the mass of a dried soil to the total volume of the soil The Modeling Environment 3 36 Processing Modflow Chemical Reaction Package MTRCT1 Type of Sorption OK Linear equilibrium isotherm Freundlich nonlinear equilibrium isotherm Cancel Langmuir nonlinear equilibrium isotherm C No sorption Help x Simulate the radioactive decay or biodegradation RHOB is the bulk density of the porous medium in the aquifer M L 3 SP1 is the Langmuir sorption equilibrium constant KI L 3 M SP2 is the total concentration of sorption sites available M M RC1 is the first ord
237. n 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 and BMP Windows bitmap formats Due to PMPATH s intensive graphical capability there is no need for additional packages for graphical representations of the simulation results 4 1 1 The Semi analytical Particle Tracking Method gt Theory 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 Additional codes are added to PMPATH to enable the computation of groundwater paths under transient flow conditions The following briefly describes Pollock s algorithm and the modified algorithm used in PMPATH 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 OV OV OV Nax wanah X Z Sx sy s Ww 4 1 x oy dz at oy where Vo Vey 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 T is a volumetric flux per unit volume and r
238. n assumed l foot thickness of the riverbed Actually any large streambed conductance value can be used as long as the head value in the model cell that corresponds to the river remains constant during the simulation Results of varying the streambed conductance value indicates that for this problem streambed conductances greater than 10 ft d produce nearly the same results The Streamflow Routing Package is not really needed to simulate this condition as the river could have been represented using constant head cells The simulation was done to determine if the package correctly accumulates flow from the aquifer into the stream Annual recharge to the aquifer was 1 5 ft and it was applied evenly over the aquifer However the daily recharge rate varied according to a sinusoidal distribution for the first 180 days while no recharge was allowed for the following 180 days Fig 5 21 Simulation Results The aquifer is simulated using one model layer Specification of the elevations of layer top and bottom are not necessary because the layer is 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 a constant The distribution used in the simulation is also shown in Fig 5 21 A total of six 360 day infiltration peri
239. n of Gelhar and Collins 1971 See section 7 4 of the manual of MT3D for details A numerical model consisting of 21 columns 15 rows and 8 layers is used to solve the 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 See section 7 5 of the manual of MT3D for details This example illustrates the application of MODFLOW and MT3D to a problem involving transport of contaminants in a two dimensional heterogeneous aquifer See section 7 6 of the manual of MT3D for details This example illustrates the application of MT3D to an actual field problem involving evaluation of the effectiveness of proposed groundwater remediation schemes See section 7 7 of the manual of MT3D for details Table 5 2 Reconstructed MT3D examples Applications and Sample Problems Processing Modflow 5 37 5 14 A Field Application Location PMWIN EXAMPLES PMEX EXAMPLE Problem Description and Modeling Approach This example shows a simplified model for the landfill shown on the cover page The plan view of the model area is illustrated in Fig 5 33 Benzene is dissolved in the groundwater and enters the aquifer system with a concentration equal to 100x10 kg m 100 ug 1 A numerical model was developed for this site to calculate the steady state groundwater flow Under steady state flow conditions the concentration distri
240. n the array control record The control record is read from the input unit number specified for the major option of the Basic Package input file that is requesting the array For example the Recharge Package uses U2DREL to read the RECH array The input unit for the recharge option is contained in IUNIT 8 and accordingly the RECH array control record is read on this input unit FOR REAL ARRAY READER U2DREL or U1DREL Data LOCAT CNSTNT FMTIN IPRN Format 0 F10 0 5A4 I10 FOR INTEGER ARRAY READER U2DINT Data LOCAT ICONST FMTIN IPRN Format 0 TLO 5A4 BLO Explanation of Fields Used in Input Instructions LOCAT indicates the location of the data which will be put into the array f LOCAT lt 0 the sign is reversed to give the unit number from which an unformatted record will be read f LOCAT 0 every element in the array will be set equal to the value CNSTNT ICONST f LOCAT gt 0 it is the unit number from which data values will be read in the format specified in the third field of the array control record FMTIN CNSTNT ICONST is a constant Its use depends on the value of LOCAT f LOCAT 0 every element in the array is set equal to CNSTNT ICONST f LOCAT O and if CNSTNT ICONST O every element in the array is multiplied by CNSTNT ICONST FMTIN is the format of records containing the array values It is used only if the first field in the array control record LOCAT contains a positive number The format must be
241. ncentration cell 2 the concentration is constant constant concentration cell or 3 the cell is an inactive concentration cell It is suggested to use 1 for an active concentration cell 1 for a constant concentration cell and 0 for an inactive concentration cell In MT3D no flow or dry cells are automatically converted into 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 starting concentration remains the same at the cell throughout the simulation A constant head cell may or may not be a constant concentration cell The starting concentration is specified by choosing Starting Values gt Concentration from the Parameters menu Top of Layers TOP MODFLOW reads the top elevation only for layers of type 2 or 3 Top of Layers is required if you want to use PMPATH MT3D and MODPATH or if you let PMWIN calculate The Modeling Environment Processing Modflow 3 13 transmissivity vertical leakance or confined storage coefficient see Layer Type above Bottom of Layers BOT MODFLOW reads the bottom elevation only for layers of type 1 or 3 Bottom of Layers is required if you want to use PMPATH MT3D and MODPATH or if you let PMWIN calculate transmissivity vertical leakance or confined storage coefficient see Layer Type above
242. ncentration value for an inactive concentration cell ICBUND 0 and NPRS is a flag indicating the frequency of the output and also indicating whether the output frequency is specified in terms of total elapsed simulation time or the transport step number If NPRS 0 simulation results will be saved at the end of each time step If NPRS lt 0 simulation results will be saved whenever the number of transport steps is an even multiple of NPRS If NPRS gt 0 simulation results will be saved at times as specified in the Output Time table as shown in Fig 3 31 The Output Time table appears when you have specified a positive NPRS gt 0 and pressed the Tab Key The Output Time table disappears when you have specified NPRS 0 and pressed the Tab key MT3D Output Control Output Terms F Concentration ASCII Number of Particles ASCII Cancel Retardation Factor ASCII Dispersion Coefficient ASCII Concentration Unformatted Options CINACT 1E 30 NPRS fo Fig 3 30 The MT3D Output Control dialog box The Modeling Environment Processing Modflow 3 43 MT3D Output Control Output Terms o F Concentration ASCII Number of Particles ASCII Cancel f Retardation Factor ASCII Dispersion Coefficient ASCII Help Concentration Unformatted Options CINACT 1E 30 NPRS 12 3 15E 07 6 3E 07 9 45E 07 1 26E 08 1 575E 08 1 89E 08 2 205E 08
243. nd for 60 days following the flood was first to calculate a distribution of river stage 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 shown in Fig 5 23 then was calculated by rearranging equation 5 and solving for streamflow The streamflow distribution was calculated from the river stage distribution a river width of 100 ft a roughness coefficient of 0 02377 a slope of 0 0001 and a constant C see equation 3 12 of 1 486 4 2 4 07 3 8 Solution from equation 5 3 6 Flow assigned to stream 3 4 for each stress period 3 2 3 0 2 8 2 6 2 4 2 2 2 07 7 1 8 10 20 30 40 50 60 70 80 90 Streamflow in thousands of cubic feet per seco Times in days since start of flood Fig 5 23 Distribution of streamflow for a 30 day flood event used for the simulation after Prudic 1988 Applications and Sample Problems Processing Modflow 5 27 Simulation Results Streamflow for the first 30 days was divided into 1 day periods for simulation Fig 5 24 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 simu
244. ned aquifer releases from storage per unit surface area of aquifer per unit decline in the water table Specific yield is required for layers of type 1 2 and 3 Refer to Bear 1972 or Freeze and Cherry 1979 for more information about the storage terms and their definitions Effective Porosity Effective porosity is used by the programs PMPATH MODPATH and MT3D to calculate the average velocity of the flow through the porous medium The Modeling Environment Processing Modflow 3 17 3 3 4 The Packages Menu Well WEL1 In Modflow an injection or a pumping well is represented by a model cell The injection or pumping rates are specified by using the Data Editor Negative cell values are used to indicate pumping wells while positive cell values indicate injection wells 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 penetrates more 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 The injection or pumping rate for each layer Q can be approximately calculated by dividing the total rate Q iota in proportion to the layer transmissivities McDonald an
245. nes A zone is a subregion of a model for which a water budget will be calculated A zone is indicated by a zone number ranging from 0 to 50 A zone number must be assigned to each model cell The zone number 0 shows that a cell is not associated with any zone Follow the steps 3 to 5 to assign zone numbers to the first and 2 to the second layer 3 Choose Matrix gt Reset from the Value menu or press Ctrl R type 1 in the dialog box then click OK 4 Press PgDn to move to the second layer 5 Choose Matrix gt Reset from the Value menu or press Ctrl R type 2 in the dialog box then click OK 6 Choose Leave Editor from the File menu or click the Leave Editor icon 7 Click OK in the Water Budget dialog box PMWIN calculates and saves the flows in the file path W ATERBDG DAT as shown in Fig 2 10 Your First Groundwater Flow Model with PMWIN 2 12 Processing Modflow The unit of the flows is L T Flows are considered IN if they are entering a zone Flows between subregions are given in a flow matrix Water budgets are calculated for each zone in each layer and each time step HORIZ EXCHANGE gives the flows which flow horizontally across a zone s boundary EXCHANGE UPPER or EXCHANGE LOWER give the flows which come from or go to the upper or lower adjacent layers Consider ZONE 1 and LAYER 1 the flow IN 1 5266858 10 m s of EXCHANGE LOWER flows from the second layer into zone 1 and flow OUT 3 6502272 10 m s l
246. nfiguration of the aquifer system Applications and Sample Problems 5 4 Row Column 1 OAINDNHWN 9 10 11 12 13 14 15 OODOOMOOTCOOMmMAAANANNAHHA HASH Table 5 1 River data Stage ft 100 0 100 0 100 0 99 0 99 0 98 0 97 0 96 0 95 0 94 0 94 0 94 0 94 0 93 0 93 0 Bore Row Column 14 11 13 8 4 ONDNDNFWN HE _ 10 11 O NWN NO Table 5 2 Measurement data Simulation Results 1 4 13 1 12 6 3 10 14 18 15 Processing Modflow Riverbed Elevation ft 90 0 90 0 90 0 89 0 89 0 88 0 86 0 86 0 85 0 84 0 84 0 84 0 84 0 83 0 83 0 Head ft 124 0 119 9 113 9 116 1 113 0 114 0 108 5 111 7 107 6 111 3 115 6 Transmissivity and recharge are defined as parameters p1 and p2 and estimated by PEST The estimation program records the optimised parameter values and the correlation coefficient matrix to the run record file as shown below Parameter pl p2 Estimated value 1 000282E 02 1 996080E 08 95 percent confidence limits lower limit upper limit 9 724991E 03 1 028859E 02 1 985581E 08 2 006578E 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 0 9572 1 000 1 000 0 9572 Applications and Sample Problems Processing Modflow 5 5 The diagonal
247. nput to and output from the model are associated with each stress period Simulation of one complete cycle of the loading to the precision shown in Fig 5 28 would require 360 stress periods As an alternative way of simulating a specified boundary head the Time Variant Specified Head Package was used For each time step within a stress period the value of each specified head is linearly interpolated Applications and Sample Problems Processing Modflow 5 33 from the user specified starting and ending heads of the period and the proportion of elapsed time within the stress period to length of the stress period Fig 5 30 shows the simulated total compaction A comparison of the results of the IBS1 Package with those of one dimensional compaction model COMPAC1 Helm 1975 can be found in Leake and Prudic 1991 O10 ess5esses in a ty AR L 1 l I I I I I l I I I l l i I l l l l i I Bea Sa Witt See ae ee ees Paryse I l I I I I l l E B04 ts oe Suede aera EOR ener o l l l l 3 G l l l I E 0 6 l I l l Oi pS H Ses Venues oes oe fe E a R l I l l l I l I T I I i I l l I i 0 8 i l DA OPE Me a eee a ye a eR ay I I l I l I l l I L I l l l l I l l I 1 0 0 360 720 1080 1440 1800 Elapsed Simulation Time days Fig 5 30 The computed total compaction Applications and Sample Problems 5 34 Processing Modflow 5 13 Two Dimensional Transport in a Uniform Flow Field Location PMWIN EXAMP
248. ns of MT3D 5 Using PMWIN with your MODFLOW 6 Running MODPATH with PMWIN 7 Input data files for the supported programs References Preface Processing Modflow was originally developed for a remediation project of a disposal site in the coastal region of Northern Germany several years ago At the beginning of the work the code was designed as a pre and postprocessor for MODFLOW The size of the code grew up as we began to add several additional options and performances for supporting the particle tracking code MODPATH and the solute transport program MT3D In the mean time various codes were developed by numerous investigators for simulating specific features of the hydrologic system with MODFLOW In these days programs for the parameter estimation and model calibration such as PEST or MODFLOW P are also available Two years ago we began to prepare the Windows version of Processing Modflow with the goal of bringing various codes together in a complete simulation system We have prepared the Windows based advective transport model PMPATH and added options for supporting the codes including MODFLOW MODPATH MODPATH PLOT MT3D and PEST We incorporated MODFLOW PMPATH and the educational version of PEST and MT3D in the simulation system We have made efforts to explain the theory and methods used in the code and included numerous examples to facilitate the use of Processing Modflow Acknowledgments We are very grateful to John Doherty who
249. nt from which flow is 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 STR1 dialog box The specified cell values will be shown on the Statusbar gt Segment is a number assigned to a group of reaches Segments must be numbered in downstream order The maximum number allowed in PMWIN is 25 The Modeling Environment 3 20 Processing Modflow gt 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 STR1 allows the user to assign more than one reach in different segments to the same model cell Refer to the documentation of the STR1 Package for more information about the numbering scheme Streamflow L T 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 is 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 Properties are used to calculate leakage to or from the aquifer through the streambed The hydraulic conductance of the streambed CSTR is calcula
250. nt layer is shown in the Toolbar Fig 4 6 Change it first if you need to place particles into another layer Note that particles cannot be placed in inactive cells or specified head cells constant head cells gt To place a group of particles 1 Click the Set particle icon 2 Move the mouse cursor to your active model area in the top view window The mouse cursor becomes a cross hair 3 Place the cross hair where you want a corner of the Set Particle window 4 Drag the cross hair until the window covers the subregion over which particles will be placed then release the mouse button A Particle Placement dialog box will appear Fig 4 8 Where NI NJ and NK are the number of particles in I J and K directions respectively These numbers can range from 0 to 999 Using NI NJ and NK particles can be placed either on cell faces or within cells which lie in the Set Particle window In the case shown in Fig 4 8 one particle will be placed within each cell and 4 2x2 particles will be placed on the cell face 3 New particles will get the color and the retardation factor given in the dialog box gt To place a single particle 1 Click the Set particle icon 2 Change the vertical local coordinate and the particle color for the definition of the vertical local coordinate see equation 4 7 and Fig 4 6 3 Move the mouse cursor to the desired position in the top view window and click the right mouse button A particle will be placed
251. ntration should be saved in a default unformatted file MT3D UCN for a continuation run or for post processing purposes If SAVUCN T the concentration will be saved in file MT3D UCN In addition the model spatial discretization information will also be saved in another default file named MT3D CNF to be used in conjunction with MT3D UCN for post processing If SAVUCN F neither MT3D UCN nor MT3D CNF is created is a flag indicating the frequency of the output and also indicating whether the output frequency is specified in terms of total elapsed simulation time or the transport step number Note that what are actually printed or saved is controlled by the input values entered in the 15 data If NPRS gt 0 simulation results will be printed or saved at times as specified in the 17 data TIMPRS NPRS If NPRS 0 simulation results will not be printed nor saved except at the end of each stress period If NPRS lt 0 simulation results will be printed or saved whenever the number of transport steps is an even multiple of NPRS is the total elapsed time at which simulation results are printed to the standard output file or saved in the default unformatted concentration file MT3D UCN If NPRS gt 8 enter TIMPRS in as many lines as necessary Appendix A 34 NOBS KOBS CHKMAS PERLEN NSTP TSMULT TSLNGH DTO MXSTRN Appendix Processing Modflow is the number of observation points at which the concentration wil
252. nts Itrib 2 is the number of the second tributary segment For a segment with no tributary Itrib 2 must be specified as zero for a diversion segment 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 Appendix A 28 Processing Modflow Horizontal Flow Barrier Package Input for the Horizontal Flow Barrier Package HFB1 is read from the unit specified in IUNIT 16 FOR EACH SIMULATION 1 Data NHFB Format I10 The following input data are read one layer at a time that is all the data for layer 1 are read first then all the data for layer 2 and so forth FOR EACH LAYER 23 Data NBRLAY Format I10 3 Data IROW1 ICOL1 TROW2 ICOL2 HYDCHR Format I10 I10 I10 I10 F10 0 The 3 data consists of one record for each horizontal flow barrier If NBRLAY is zero the 3 dat a will not be read Explanation of Fields Used in Input Instructions NHFB NBRLAY NOTE is the total number of horizontal flow barriers in the finite difference grid is the number of horizontal flow barriers in a layer Within a layer the location of a horizontal flow barrier is identified by the two cells on either side of the barrier The row and column numbers of these two cells are IROW1 ICOL1 the cells are identified TROW1 ICOL1 TROW2 ICOL2 HYDCHR Appendix and IROW2 ICOL2 respectively There is no requirement r
253. nts 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 exponents e g F 1 produce a surface with peaks to attain the proper values at the data points An exponent of F 2 is suggested by Shepard 1968 20 Interpolated data value 10 20 30 40 50 Fat F2 Erea ey O data point Fig 4 14 Effects of different weighting exponents Modeling Tools 4 22 Processing Modflow gt Akima s bivariate interpolation This method creates a triangulation of the measurement data points and performs interpolation by using a bivariate quintic 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 gt 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 gt Kriging The Kriging method is popularized by Math ron 1963 in honor of D G Krige a noted South African mining geologist and statistician PMDIS assumes that the measurement data are stationary and isotropic The Kriging method est
254. nu Contents command by searching for specific topics with the Help Search tool or by pressing F1 to get context sensitive Help on the PMWIN modeling environment 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 you can either choose Search from the Help menu or click the Search button on any Help topic screen To search Help 1 From the Help menu choose Search You can also choose 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 name and then press ENTER or choose Go To to view the topic Context Sensitive Help Many parts of PMWIN are context sensitive Context sensitive means you can get Help on these parts directly without having to go through the Help menu For example to get Help on any dialog box of PMWIN just click the Help button Introduction Processing Modflow 2 1 2 Your First Groundwater Flow Model with PMWIN It takes just a few minutes to build your first groundwater flow model with PMWIN You create a groundwater model by choosing New Model from the File menu Next you determine the size of the model grid by choosing Mesh Size from the Grid menu Then you specify the geometrical setup and assign the model parameters such as hydraul
255. number of iterations required for convergence RELAX is not used if NPCOND 1 is used when NPCOND 2 to indicate whether the estimate of the upper bound on the maximum eigenvalue is 2 0 or whether the estimate will be calculated NBPOL 2 is used to specify the value as 2 0 for any other value of NBPOL the estimate is calculated Convergence is generally insensitive to this parameter NBPOL is not used if NPCOND does not equal 2 is the printout interval for PCG If IPRPCG is equal to zero it is changed to 999 The extreme head change and residual positive or negative are printed for each iteration of a time step whenever the time step is an even multiple of IPRPCG The printout also occurs at the end of each stress period regardless of the value of IPRPCG is a flag which controls printing from the solver If MUTPCG 0 printing from the solver is suppressed If MUTPCG 1 the number of iterations is printed but the lists of extreme head changes and residuals is suppressed If MUTPCG 2 all printing is suppressed is a flag which is used when NPCOND 1 to control whether the same Cholesky decomposition may be used for multiple calls to PCG2AP IPCGCD should be zero for most applications However future packages might benefit from nonzero values of IPCGCD Appendix A 26 Processing Modflow Streamflow Routing Package Input for the Streamflow Routing Package STR1 is read from the unit specified in IUNIT 14 FOR EACH SIMULATION Ig Data
256. odel 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 is denoted by 2 6 1 Columns J 1 2 345678 9 10 2L OL ALALLA A S oF gt Rows 1 S 1 i 2 Layers K P 3 4 Fig 2 2 Spatial discretization of an aquifer system and the cell indices gt To generate the model grid 1 Choose Mesh Size from the Grid menu A Model Dimension dialog box will come up Fig 2 3 2 Type 2 for the number of layers 30 for the numbers of columns and rows and 20 for the size of columns and rows 3 Click OK PMWIN changes the pull down menus and shows the generated model grid Fig 2 4 Some menus items are dimmed as they will not be used here PMWIN allows you to shift or rotate the model grid change the width of each model column or row or add or 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 icon Your First Groundwater Flow Model with PMWIN 2 4 Processing Modflow Model Dimension Layers Size 20 000 Rows
257. odel layers that have interbed storage e Compaction of individual layers is the sum of the calculated compaction and the user specified starting compaction in each layer e Preconsolidation head is the previous minimum head value in the aquifer For any model cells in which the specified preconsolidation head is greater than the corresponding value of starting head value of the preconsolidation head will be set to that of starting head Subsidence compaction and preconsolidation head are saved in the unformatted binary file INTERBED DAT e 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 is created by the package named LKMT The LKMT package is incorporated in the version of MODFLOW provided by the PMWIN or MT3D software You must use these two versions of MODFLOW if you intend to run MT3D subsequently If it is preferred to use a version of MODFLOW other than these two you should add the LKMT package into MODFLOW Refer to the manual of MT3D for how to do this Modflow Output Control Output Terms i Hydraulic Heads Drawdowns Cell by cell Flow Terms i Subsidence from IBS1 Help i Compaction of Individual Layers from IBS1 Preconsolidation Heads from IBS1 l Echo Print of Input Values I Interface file to MT3D OK gid Cancel Output Fr
258. ods 144 stress periods each with a length of 15 days were 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 5 22 The location of the well is shown in Fig 5 20 The same results were obtained using the River Package Applications and Sample Problems Processing Modflow 5 25 2 0 1 8 Annual recharge is 1 5 feet 2 1 6 1 4 F recharge for analytical solution z 1 2 a S 1 0 recharge rates assigned to each c lt ae Ega 15 day period in model simulation S 0 6 o 2 0 4 Pa 0 2 x e 0 0 SJ 0 60 120 180 240 300 360 Times in days since start of infiltration period Fig 5 21 Distribution of recharge used for analytical solution and the model simulation after Prudic 1988 simulation results analytical solution 6 2E 1 ial let eel ete ele eel tirara ee Ge ee ee ee ee a ee ee ee Cee Pee Seer See eee Sy ee Cee ne Sea Eee Pa 1 1 1 1 1 1 ie eee tele een Cetin eee a a r ibn tein hernia Groundwater level in feet above arbitrary datum 5 4E 1 1 56E 8 1 87E 8 Elapsed Simulation Time second Fig 5
259. of the hydraulic head in the aquifer Discharge rate to the drain Q is calculated by Q C h d 3 6 The Modeling Environment 3 18 Processing Modflow The value C of a drain cell is often given by C22 Ke L 3 7 where L is the length of the drain within a cell The value Kis a equivalent 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 Drain DRN1 Drain Hydraulic Conductance L 2 T 001 Elevation of the Drain L 12 Current Column 14 Current Row 38 Fig 3 12 The Drain DRN1 dialog box General Head Boundary GHB1 The General Head Boundary Package GHB1 is used to simulate head dependent flow boundaries Cauchy boundary conditions Similar tothe Drain Package aGeneral Head Boundary cell GHB cell is defined by two cell values GHB hydraulic conductance C L T Hydraulic head at the boundary h L The values C and h of a GHB cell are shown on the Statusbar Flow through the general head boundary Q L T is calculated by Q C h h 3 8 where his the hydraulic head in the aquifer A GHB cell is equivalent to a constant head cell if a large C is used The values C and h are constant during a given stress period For transient flow simulations involv
260. ogram However the input to each of these arrays is handled as a series of two dimensional arrays one for each layer in the grid FOR EACH STRESS PERIOD 9 Datars Format F10 0 110 F10 0 PERLEN NSTP TSMULT Explanation of Fields Used in Input Instructions HEADNG NLAY NROW NCOL NPER ITMUNI IUNIT Appendix is the simulation title that is printed on the simulation record file It may be up to 132 characters long 80 in the first record and 52 in the second Both records must be included even if they are blank is the number of model layers is the number of model rows is the number of model columns is the number of stress periods in the simulation 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 is a 24 element table of input units for use by all major options If IUNIT n lt 0 the corresponding major option is not being used If l1UNIT n gt 0 the corresponding major option is being used and data for that option will be read from the unit number contained in IUNIT n T
261. omatically assigned so you get a gradational change from one color to another e To specify gradational fill colors Assign YES to the Active flag of desired search ranges rows in the Trace table Click Spectrum A Color Spectrum dialog box appears Fig 3 43 3 Inthe Color Spectrum dialog box click the Minimum button to display a Color dialog box In the Color dialog box select a color and click OK Repeat this procedure for the Maximum button 4 Inthe Color Spectrum dialog box click OK A gradation of colors from the minimum to the maximum is assigned to each active row of the table or Color Spectrum Minimum Maximum Fig 3 43 The Color Spectrum dialog box gt Level Using Level you can automatically assign regularly spaced search ranges to each active rows in the Trace table e To specify regularly spaced search ranges Assign YES to the Active flag of desired search ranges rows in the Trace table Click Level A Search Level dialog box appears Fig 3 44 3 In the Search Level dialog box type the smallest value in the Mimimum edit field and type largest value in the Maximum edit field Click OK when finished The regularly spaced search ranges are assigned to active rows For example the smallest value could be defined as 10 the largest could be 60 and there are five active rows The search ranges would be the same as shown in Fig 3 41 Se The Modeling Environment 3 66 Processing Modflow
262. on 4 Check simulation results and produce output Create a Flow Model The first step in running a flow simulation is to create a new model gt To create a flow model 1 Choose New Model from the File menu A New Model dialog box will appear Select a directory for saving the model data such as C PMWIN EXAMPLES SAMPLE and type the file name SAMPLE for the sample model A PMWIN model must always have the file extension MDL It is a good idea to save every model in a separate directory where the model and its output data will be kept This will also allow you to run several models simultaneously multitasking If a desired directory for saving a new model is not available you have to use the File Manager of Windows or other utilities to create the directory 2 Click OK PMWIN takes only a few seconds to create the new model and show the model name on the title bar Your First Groundwater Flow Model with PMWIN Processing Modflow 2 3 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 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 m
263. only way for cells in layer 1 to become wet because heads in layer 2 are always below the bottom of layer 1 Steady state heads along row 1 in layer 1 range from 29 92 feet in cell J I KJ 1 1 1 to 20 75 feet in cell 40 1 1 Fig 5 19 shows the contours of steady state heads in layer 1 E h 21 0 22 8 ft MM 22 8 24 6 ft h 24 6 26 4 ft P h 26 4 28 2 ft Plan View ME 28 2 30 0 ft Fig 5 19 Contours of the simulated steady state heads Applications and Sample Problems Processing Modflow 5 23 5 9 Simulation of an Aquifer System with Irregular Recharge and a Stream Location PMWIN EXAMPLES STRI EX1 Problem Description and Modeling Approach This example is from the first test problem of the Streamflow Routing STR1 Package For this example 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 5 20 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 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
264. option generally leads to smaller mass balance discrepancy in nonuniform or diverging converging flow fields gt NPL is the number of initial particles per cell to be placed in cells where DCCELL lt DCEPS Generally NPL can be set to O since advection is 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 NPH is the number of initial particles per cell to be placed at cells where DCCELL gt 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 particles are randomly distributed within the cell block If the fixed pattern is chosen NPH is divided by NPLANE to yield the number of particles to be placed per vertical plane which is rounded to one of the values shown in Fig 3 23 gt NPMIN is the minimum number of moving 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 sufficient number of particles NPMIN can be set to 0 in relatively uniform flow fields
265. ord is needed only if the length of time steps for the head solution is not based on a geometric progression Enter TSLNGH in as many lines as necessary if NSTP gt 8 is the user specified transport stepsize The program will always calculate a maximum transport stepsize which meets the various stability criteria Setting DTO to zero or a negative value causes the model calculated transport stepsize to be used in the simulation However the model calculated DTO may not always be optimal In this situation DTO should be adjusted to find a DTO which leads to the best results If DTO is given a value greater than the model calculated stepsize the model calculated stepsize instead of DTO will be used in the simulation is the maximum number of transport steps allowed for one time step of the head solution If the number of transport steps within one time step exceeds MXSTRN the simulation is terminated Processing Modflow A 35 Advection Package Input to the of MT3D The is needed un Advection Package MTADV1 is read on unit 2 which is preset in the main program input file is needed only if the Advection Package is used however this package der almost all circumstances FOR EACH SIMULATION 15 Data Form 2 Data Form Enter t 3s Data Form Enter t 4 Data Form Enter t 5 Data Form 7 MIXELM PERCEL MXPART at 110 F10 0 TLO 2 ITRACK WD at 110 F10 0 he 3 Data if MIXELM 1 or 3
266. p Appendix A 8 Processing Modflow Internal data files of PMWIN 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 Geometrical Setting Up and Boundary Conditions Extension Description BOT CBC Elevation of the bottom of layers DWA CBC Wetting threshold BCF2 Package HEA CBC Initial hydraulic heads IBD CBC IBOUND matrix TOP CBC Elevation of the top of layers BOZ ZONE Elevation of the bottom of layers DWZ ZONE Wetting threshold BCF2 Package HEZ ZONE Initial hydraulic heads IBZ ZONE IBOUND matrix TOZ ZONE Elevation of the top of layers X Cell sizes in x direction Y Cell sizes in y direction ONLY MT3D TIC CBC ICBUND matrix TSC CBC Initial concentration MTO ZONE ICBUND matrix MT1 ZONE Initial concentration Aquifer Properties Extension Description CON CBC horizontal hydraulic conductivity ETG CBC Transmissivity LEA CBC Vertical hydraulic conductivity LKN CBC Vertical leakance POR CBC Effective porosity SCC CBC Storage coefficient STO CBC Specific storage TAL CBC Longitudinal dispersivity YLD CBC Specific yield COZ ZONE horizontal hydrauli
267. periods i e time intervals during which all external excitations or stresses are constant which are in turn divided into time steps In the MT3D model each time step is further divided into smaller time increments called transport steps The length of stress periods is not relevant to a steady state flow simulation However if you want to perform contaminant transport simulation with MT3D at a later time you must specify the actual time length in the table Click OK to accept the default values To specify the initial hydraulic head Choose Starting Values gt Hydraulic Heads from the Parameters menu PMWIN shows the model grid Now you can specify the initial hydraulic heads for each model cell The initial hydraulic head at a constant head boundary will be kept constant during the flow simulation Choose Matrix gt Reset from the Value menu or press Ctrl R and type 8 in the dialog box then click OK Move the grid cursor to the upper left model cell Press the right mouse button and type 9 in the Cell Value dialog box then click OK Now turn Duplication on by clicking the Duplication icon s The small box on the lower right corner of this icon will be highlighted The current cell value will be duplicated to all cells passed by the grid cursor if it is moved while 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 s
268. plate File RIVTP Recharge Package Template File RCHTP Well Package Template File WELTP Drain Package Template File DRNTP Evapotranspiration Package Template File EVTTP General Head Boundary Package Template File GHBTP Stream Routing Flow Package Template File STRTP Interbed Storage Package Template File IBSTP Grid Specification File used by MODBORE EXE filen Bore Listing File used by MODBORE EXE BOREL Bore Coordinates File used by MODBORE EXE BOREC AT AT AT AT AT AT AT AT AT AT DAT DAT DAT DAT DAT T DAT 0 DAT DAT DAT DAT DAT DAT UCT DA TL DAT L DAT L DAT L DAT L DAT L DAT L DAT L DAT L DAT L DAT ame GR ST DA OOR DA A 43 are saved in MODF LOW T D T ue x filename is the file name of your model The grid specification file provides the grid geometry and location details File Format 1 Data NROW 2 Data X 3 Data DELR NCOL 4 Data DELC NROW The format of this file is given below NCOL y ANGLE Explanation of Fields Used in Input Instructions NROW NCOL X Y ANGLE DELR DELC is is is is is the the the the the number of model rows number of model columns x coordinate of the top left corner of the model grid y coordinate of the top left corner of the model grid rotation angle expressed in degrees and measured countercolckwise from the positive x axis is the cell width along rows
269. plots Report quality graphics may be saved to a wide variety of file types including SURFER DXF HPGL and BMP Windows Bitmap System Requirements Hardware Personal computer running Microsoft Windows 3 1 or later or Windows 95 8 MB of available memory 16MB or more recommended One 3 5 high density disk drive and a hard disk complete installation requires 27MB EGA or higher resolution monitor Microsoft Mouse or compatible pointing device Software The models MODFLOW MODPATH and MT3D must be compiled by Lahey Fortran F77L EM 32 Setting Up PMWIN You install PMWIN on your computer using the program SETUP EXE contained in disk 1 The Setup program installs PMWIN itself and other program components from the distribution disks to your hard disk Note that you cannot simply copy files from the distribution disks to your hard disk and run PMWIN You must use the Setup program which decompresses and installs the files in the appropriate directories After having installed PMWIN you should add the following entries to the file CONFIG SYS and AUTOEXEC BAT and reboot your computer CONFIG SYS FILES 80 Introduction 1 4 Processing Modflow AUTOEXEC BAT SET PESTDIR path where path is the subdirectory of the PEST programs If you do not have PEST path should be the subdirectory of PMWIN e g C PMWIN Online Help The online help system references nearly all aspects of PMWIN You can access Help through the Help me
270. projection of velocity vectors of each active model cell can be shown on the Top view window Click the color button 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 Vector size defaults to 25 and can range from to 2 147 483 647 e Cross Sections are visible if the Visible box is checked To display the model grid on the cross section check the Show Grid check box Because of the possible usage of deformed grid Fig 4 5 only the vertical model grid will be displayed on the cross section windows Use Scaling factor for the height exaggeration to change the appearing height of the model Using a larger scaling factor let you see the projection of the pathlines on the cross section windows in greater details The scaling factor can range from 0 01 to 1000 Note that PMPATH cannot display the cross sections if the model thickness or the exaggeration factor is too small In this case the Visible check box will unchecked automatically gt Particle Tracking Options From the Options menu choose Particle Tracking to modify any of the settings in the Particle Tracking Options dialog box shown in Fig 4 10 The available settings are summarized in Current Time Tracking Step Time Mark Simulation Mode Stop Condition Recharge and Evapotranspiration e Current Time You can move to any stress period and time step as long as the resulting heads an
271. provided the educational release of PEST explanations of the program parameters and many valuable comments and criticisms We are indebted to Chunmiao Zheng of the Department of Geology at the University of Alabama who provided the educational release of the solute transport model MT3D and the corresponding input instructions Many thanks are due to many of our friends and colleagues for their contribution in developing checking and validating the various parts of this software Wen Hsing Chiang Wolfgang Kinzelbach Processing Modflow 1 1 1 Introduction What Is PMWIN Processing Modflow for Windows PMWIN is a simulation system for modeling groundwater flow and transport processes with the modular three dimensional finite difference groundwater model MODFLOW of the U S Geological Survey McDonald et al 1988 the particle tracking model PMPATH for Windows Chiang 1994 or MODPATH Pollock 1988 1989 1994 the solute transport model MT3D Zheng 1990 and the parameter estimation program PEST Doherty et al 1994 The codes supported by PMWIN are widely used and available at nominal cost The applications of MODFLOW to the description and prediction of the behavior of groundwater systems have increased significantly over the last few years Since the publication of MODFLOW various codes have been developed by numerous investigators for simulating specific features of the hydrologic system MODFLOW can simulate the effects of wells
272. r Preconsolidation head is the previous minimum head value in the aquifer For any model cells in which specified HC is greater than the corresponding value of initial head see the input instruction of the Basic Package value of HC will be set to that of initial head Sfe is an array specifying the dimensionless elastic storage factor for interbeds present in model layer The storage factor may be estimated as the sum of the products of elastic skeletal specific storage and thickness of all interbeds ina model layer sfv is an array specifying the dimensionless inelastic storage factor for interbeds present in model layer The storage factor may be estimated as the sum of the products of inelastic skeletal specific storage and thickness of all interbeds in a model layer Com is an array specifying the starting compaction in each layer with interbed storage Compaction values computed by the package are added to values in this array so that printed or stored values of compaction and land subsidence may include previous components Values in this array do not affect calculations of storage changes or resulting compaction For simulations in which output values are to reflect compaction and subsidence since the start of the simulation enter zero values for all elements of this array ISUBFM is a code for the format in which subsidence will be printed ICOMFM is a code for the format in which compaction will be printed IHCFM is a code for the
273. r having specified these data and clicked OK the Grid Editor appears Fig 3 2 The Grid Editor shows the plan view of the model grid An index notation J I is used to describe the location of the grid cursor in terms of columns J and rows I At the first time you use the Grid Editor you can insert or delete columns or rows see below After having leaved the Grid Editor and saved the grid you can subsequently refine the existing model grid by calling the Grid Editor again In each phase you can change the size of each column or row If the grid is 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 This is true for hydraulic conductance of the head dependent boundaries i 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 because these number cannot be retained automatically gt To change the width of a column and or a row 1 Click the Assign Value icon The Modeling Environment 3 2 v Wier v PUD Processing Modflow The grid cursor appears only if the Assign Value icon is pressed down You do not need to click this icon if it is already pressed down Move the grid cursor by using the arrow keys or by clicking the mouse on th
274. r left cell 1 30 1 of the model grid The value of 1 is duplicated to all cells on the west side of the model 6 Move the grid cursor to the upper right cell 30 1 1 Your First Groundwater Flow Model with PMWIN 2 6 Processing Modflow 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 is duplicated to all cells on the east side of the model 8 Turn Layer Copy on by clicking the Layer Copy icon The small box on the lower right corner of this icon will be highlighted 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 Layer Copy off by clicking the Layer Copy icon 9 Move to the second layer The cell values of the first layer are copied to the second layer 10 Choose Leave Editor from the File menu or click the Leave Editor icon Processing Modflow SAMPLE MDL bd File Value Options Help HERRES i 587 5796 390 7643 11 1 time independent Boundary Condition IBOUND H Active 1 Inactive 0 Fixed Head 1 g Fig 2 6 Top view of the model grid Model data are assigned to each cell in each layer The next step is to specify the geometrical setup of the model
275. racking are very small Click the Stop button if the particle tracking simulation appears too slow Run particles forward step by step Click the Run particles step forward step by step button to move particles forward a single particle tracking step The particle tracking step length is defined in the Particle Tracking Options dialog box Run particles forward Click the Run particles forward button to execute forward particle tracking for a specified time length The time length is defined by the product of the number of particle tracking steps and the particle tracking step length given in the Particle Tracking Options dialog box 4 1 3 PMPATH Options There are three menu items in the Options menu of PMPATH viz Environment Particle Tracking and Maps The use of the Environment and Particle Tracking options is described below Refer to section 3 3 8 for the description of the Maps options gt Environment Options From the Options menu choose Environment to modify any of the settings in the Environment Options dialog box Fig 4 9 The available settings are summarized in the Top View and the Cross Sections groups The Top View group contains the Grid Appearance Contours and Velocity Vectors groups The settings are described below Environment Options T p Viaw Cross Sections Grid Appearance gt s O X Grid KX well discharge D visible E X inactive Cells Well recharge C show grid E const
276. rains and Appendix A 2 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 3 7 The Result Extractor Field Interpolator and Field Generator use this file format to save the generated data File Format Ta Data NCOL NROW Z 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 Example If NCOL 6 and NROW 5 an ASCII Matrix file would be 6 5 121 152 133 144 315 516 221 252 233 244 275 7216 321 352 333 344 315 316 421 452 433 444 415 416 521 552 533 544 515 516 Or 6 5 121 152 133 144 315 516 221 252 233 244 215 216 321 352 333 344 315 316 421 452 433 444 415 416 521 552 533 544 515 516 Appendix Processing Modflow Bore file A bore file can be saved or loaded by the Bores and Observations dialog box File Format ds Data 25 Data LABEL NB XXX XXX XXX XXX The following data repeats NB times 3 Data Explanation of Fields Used in Input Instructions E SAME RECORD ARE SEPARATED BY A COMMA OR BLANK be PMWIN4000_BOR_FILE imum number of NB is 1000 ALL DATA IN TH LABEL NB XXX Active X Y Layer Draw Color Active X Y Layer is the
277. rated This allows the user to do stochastic modeling with PMWIN In stochastic modeling uncertainty due to unknown small scale distribution of the model parameters is addressed directly by assuming 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 mean value p and standard deviation o then X has the lognormal distribution PMEGN runs independently from PMWIN To start PMFGN select Field Generator PMFGN from the Run menu of PMWIN A dialog box appears Fig 4 18 PMFGN uses the mean value u standard deviation o and correlation scales in both I and J directions 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 is specified in the dialog box Realizations are saved in the ASCII Matrix format see Appendix 2 using the file names filename xxx where filename is the output file name specified in the dialog and xxx is the realization number The generated field is lognormally to base 10 distributed Using the Data Editor see section 3 3 7 you can load the generated field into an area of the model grid where the columns and rows are regularly spaced Field Generator Output Filename Without Extension le pmwin examples
278. rbed material L is the length of the river within a cell Wis the width of the river and M is the thickness of the riverbed If CR Vis unknown it must be adjusted during a model calibration Streamflow Routing STR1 The Streamflow Routing Package STR1 Prudic 1989 is 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 equal to inflow in the upstream reach plus or minus leakage from or to the aquifer in the upstream reach The accounting scheme used in STR1 assumes that streamflow entering the modeled layer 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 is formed from tributary streams is 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 segme
279. rd particle tracking scheme the simulation time limit is 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 simulation In this case particles will be stopped immediately after the start If the simulation time limit is reached and this option is not checked PMPATH calculates flowlines by using the flow field of the first or last time step Note that you cannot start backward particle tracking from the end of a transient flow simulation You can only start particles from the beginning of the last simulation time step e Recharge 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 source approximation is usually only appropriate for two dimensional areal flow models The flow velocity across the top face of a cell in the top model layer would be zero if the existing recharge is not assigned to the top face Consequently particles would never reach the top face if the backward tracking scheme is applied 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 Particle Tracking Options dialog box Fig 4 10 Recharge
280. re 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 ny Sop be Ah S 3 21 For an aquifer with n interbeds with specific storage values S Ss S and with thicknesses b bz b a single equivalent storage factor S is given by Jorgenson 1980 Soreasl SoPat Sob t 4S Pe 3 22 For the numerical implementation of the Interbed Storage Package refer to Leake and Prudic 1991 Time Variant Specified Head CHD1 For transient simulations the Time Variant Specified Head Package Leake and Prudic 1991 allows constant head cells to take on different head values for each time step You use the Time Variant Specified Head CHD1 dialog box to specify the data required by the CHD1 Package Fig 3 19 Flag 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 The Modeling Environment Processing Modflow 3 27 The CHD1 Package does not alter the way constant head boundaries are formulated in the finite difference equations of MODFLOW CHD sets the element in the IBOUND array to a negative value for all c
281. rence 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 is only 0 05 foot Thus the neighboring cell to the right is 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 is 0 3 days and the last time step is 115 385 days The specific yield is 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 criterion is 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 5 17 shows simulated water table heads along row 1 at several times during the transient simulation Steady state condi
282. repeatedly oscillates between wet and dry indicating that column 14 should be dry If horizontal wetting is used oscillation between wet and dry can be prevented by raising the wetting threshold but this also can prevent some cells that should be partly saturated from converting to wet On the left side of the model horizontal head changes between adjacent cells generally are small so head in the neighboring horizontal cells is a good indicator of whether or not a dry cell should become wet Therefore positive values of the wetting threshold THRESH are used in most of this area to allow wetting to occur either from the cell below or from horizontally adjacent cells Near the well the horizontal head gradients under pumping conditions also are relatively large consequently a negative THRESH was used at the cells above the well This prevents these cells from incorrectly becoming wet It is also possible to use a larger positive wetting threshold to prevent these cells from incorrectly becoming wet Applications and Sample Problems Processing Modflow 5 17 5 7 Simulation of a Water Table Mound Resulting from Local Recharge Location PAWIN EXAMPLES BCF2 EX2 Problem Description and Modeling Approach Localized recharge to a water 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 cont
283. rity be prepared to set them much lower Note however 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 the parameter OFFSET variable to shift the parameter domain so that it does not include zero gt FACORIG If in the course of the estimation process a parameter becomes very small the relative or factor limit to subsequent adjustment of this parameter may severely hamper its growth back to higher values resulting in very slow convergence to an objective function minimum Furthermore for the case of relative limited parameters which are permitted to change sign it is possible that the denominator of equation 3 44 could become zero To obviate these possibilities choose a suitable value for the real variable FACORIG If the absolute value of a parameter falls below FACORIG times its original value then FACORIG times its original value is substituted for the denominator of equation 3 44 For factor limited parameters a similar modification to equation 3 45 applies Thus the constraints that apply to a growth in absolute value of a parameter are lifted when its absolute value has become less than FACORIG times its original absolute value However where PEST wishes to reduce the parameter s absolute value even further factor limitations are not lifted nor are relative limitations lifted if RELPARMAX lt is less than 1 FACORIG is
284. rizontal flow barriers conceptually situated on the boundaries between pairs of adjacent cells in the finite difference grid A horizontal flow barrier is defined by assigning the following values to a model cell in the Horizontal Flow Barrier HFB1 dialog box Fig 3 17 Barrier Direction and Hydraulic Conductivity Thickness of the barrier TDW T The barrier direction indicates the cell face where the barrier is located To erase an existing barrier use zero for the barrier direction The second value TDW gives the hydraulic characteristic of the barrier In the HFB1 Package barrier thickness is included implicitly in TDW If the layer type is 1 or 3 TDW will be used by the HFB1 Package directly If a layer is confined type 0 or 2 however PMWIN assigns the product of TDW and the layer thickness to the HFB1 Package In this case you have to specify the elevations of the top and bottom of these layers although these elevations are not always required for simulating confined layers Forthenumericalimplementation of the Horizontal Flow Barrier Package refer to Hsieh and Freckleton 1993 The Modeling Environment Processing Modflow 3 25 Horizontal Flow Barrier HFB1 Barrier Direction 1 4 2 Cancel Hydraulic Conductivity Thickness of the Barrier 1 T 1 0E 8 Current Column 21 Directions Current Row 26 1 Te i 0 No Barrier Fig 3 17 The Horizontal Flow Barrier HFB1 dia
285. rn on threshold The turn on threshold is TURNON BOT THRESHI 3 24 where BOT is the elevation of the bottom of the cell and THRESH is a user specified constant called the wetting threshold A non zero value THRESH is specified for each cell that can be wetted If THRESH lt 0 only the cell below a dry cell can cause the cell to become wet If THRESH gt 0 the cell below a dry cell and the four horizontally adjacent cells can cause the cell to become wet If THRESH is zero the dry cell or the inactive cell cannot be wetted The Modeling Environment 3 28 Processing Modflow Only variable head cells either immediately below or horizontally adjacent to a dry cell can cause the cell to become wet A neighboring cell cannot become wet as a result of a cell that has become wet in the same iteration When a cell is wetted IBOUND for the cell is set to 1 which indicates a variable head cell vertical conductances are set to their original values and the hydraulic head h at the cell is set equal to one of the following h BOT WETFCT hn BOT 3 25 h BOT WETFCT THRESH 3 26 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 The user can select between equation 3 25 and 3 26 in the Wetting Capability BCF2 dialog box Fig 3 20 This dialog box appears when you select Wetting Capability BCF2 from the Packages menu The dialog also
286. s and are therefore impervious no flow boundaries The calculated concentration plume is shown in Fig 5 35 Fig 5 34 Configuration of the model grid and location of observation wells Fig 5 35 Calculate concentration plume Applications and Sample Problems Processing Modflow Appendix 1 Limitation of PMWIN This packages for their assumptions Data Editor Maximum number of layers 80 Maximum number of stress periods 1000 Maximum number of cells along rows or columns Maximum number of cells in a layer 2000 x 2000 Maximum number of zones in a layer 40 Maximum number of vertex nodes of a zone 40 Maximum number of stream segments 25 Maximum number of There is no limit to the number of wells horizontal flow barrier cells Bores and Observations Maximum number of bores 1000 Maximum number of observations 6000 Field Interpolator Maximum number of cells Maximum number of cells in a layer 250 000 along rows or columns Maximum number of input data points 2000 Field Generator Maximum number of cells in a layer 250 000 Maximum number of cells along rows or columns Water Budget Calculator Maximum number of subregions 50 section gives the size limitation of PMWIN applicability and limitations tributary segments of each stream segment 2000 4 000 000 10 general head boundary cells 2000 500 rivers A 1 Refer to the documentation of individual d
287. s been widely used Using the MOC scheme a set of moving particles is 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 these 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 One of the most desirable features of the MOC technique is that it is virtually free of numerical dispersion which creates serious difficulty in many numerical 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 amount of particles is required In the MT3D model instead of placing a uniform number of particles in every finite difference cell a dynamic approach is used to control the distribution of moving particles The number of particles placed at each cell is normally set either at a high level or at a low level according to the so called relative cell concentration gradient or DOCELL defined as 3 27 CMAX CMIN where CMAX x is the maximum concentration in the immediate vicinity of the cell i j k CMIN is the minimum concentration in the immediate vicinity of the cell 1 j k CMAX is the maximum concentration in the entire grid and CMIN
288. s have the same meaning for both head and drawdown A positive format code indicates that each IHEDFM IDDNFM IHEDUN IDDNUN INCODE IHDDFL IBUDFL ICBCFL Hdpr Ddpr Hdsv Ddsv Appendix row of data is printed completely before starting the next row when there are more columns in a row are used as required to complete the A negative format code indicates that t that number of columns that will fit many strips are used as are required to print the entire model width lute value of the format code specifies the The default code of PMWIN is 0 9G13 6 2 is called the strip format The abso printout format as follows 0 10G11 4 1 11G10 3 5 15F7 3 6 15F7 4 1 0 20F5 3 11 20F5 4 is the unit number to which heads wil is is the head drawdown ouput code data f INCODE lt 0 3 data is not read f INCODE 0 record f INCODE 2 7 T gt 0 The 3 is head and drawdown output flag f IHDDF 0 f IHDDFL 0 for each layer specified in the 3 is a budget print flag f IBUD 0 f IBUD 0 Note t stress period is a cell by cell flow term flag f BC 0 f BC 0 on ags set in the component of flow is e output flag for head printout pr 0 head pr 0 head is e output flag pr 0 f pr 0 is the output flag f Hdsv 0 head f Hdsv 0 head is the output flag f Ddsv 0 f Ddsv 0 a Li FL Li zj Li zj Li C
289. s is the steady state flag If ISS 0 the simulation is steady state If ISS 0 the simulation is transient IBCFCB is a flag and a unit number If IBCFCB gt 0 it is the unit number on which cell by cell flow terms will be recorded whenever ICBCFL see Output Control Options is set the terms which are saved will include cell by cell storage terms cell by cell constant head flows and cell by cell flow between adjacent cells If IBCFCB 0 cell by cell flow terms will not be printed or recorded If IBCFCB lt 0 flow for each constant head cell will be printed in the listing file whenever ICBCFL is set cell by cell storage terms and cell by cell flow between adjacent cells will not be recorded or printed HDRY is the head that is assigned to cells that are converted to dry during a simulation Although this value plays no role in the model calculations it is useful as an indicator when looking at the resulting heads that are output from the model HDRY is thus similar to HNOFLO in the Basic Package which is the value assigned to cells that are no flow cells at the start of a model simulation IWDFLG is a flag that determines if the wetting capability is active If IWDFLG 0 the wetting capability is inactive If IWDFLG 0 the wetting capability is active Appendix A 16 WETFCT IWETIT IHDWET LAYCON TRPY DELR DELC sfl Tran HY BOT Vcont sf2 TOP WETDRY Appendix Processing Modflow is a fac
290. s not saved is the output flag for saving preconsolidation head in an unformatted disk file f IHCSV gt 0 preconsolidation head is saved for each layer with interbed storage f IHCSV lt 0 preconsolidation head is not saved Processing Modflow A 31 Time Variant Specified Head Package Input for the Time Variant Specified Head Package CHD1 is read from the unit specified in IUNIT 20 FOR EACH SIMULATION 1 Data MXCHD Format 110 FOR EACH STRESS PERIOD 2 Data ITMP Format 110 3 Data Layer Row Column StartHead EndHead Format I10 110 110 F10 0 F10 0 The 3 data normally consists of one record for each specified head boundary cell If ITMP is zero the 3 data is not read Explanation of Fields Used in Input Instructions MXCHD ITMP Layer Row Column StartHead EndHead is the maximum number of specified head cells to be specified each stress period is a flag If ITMP lt 0 specified head boundary data from the previous stress period will be reused and the 3 data will not be read Reusing data from a previous stress period means that the head values at the start and end of the current stress period will be the same as they were at the start and end of the previous stress period If ITMP gt 0 it is the number of records of specified head boundary data that will be read for the current stress period is the layer number of the cell affected by the specified head boundary is
291. s to be placed per vertical plane which is rounded to one of the values shown in Fig 3 23 is the minimum number of moving 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 sufficient 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 0 lt NPMINE lt 4 is adequate is the maximum number of particles allowed per cell If the number of particles in a cell exceeds NPMAX particles are removed from that cell until NPMAX is met Generally NPMAX can be set to a value approximately twice the value of NPH 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 is a flag indicating the concentration interpolation method for use in the MMOC solution scheme Currently only linear interpolation is implemented Enter INTERP l1 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 is the number of particles used to approximate sink cells in the MMOC scheme The convention for is the same as that for NPH is the critical relative concentration gradient for controlling the s
292. s used Otherwise the MMOC scheme is used In MT3D particles are introduced into the flow field and moved in a continuous spatial domain according to a velocity field calculated from the hydraulic heads generated by MODFLOW The user can select a particle tracking algorithm between the first order Euler algorithm and the fourth order Runge Kutta algorithm Using the first order Euler algorithm the equation for calculating the final coordinates X Y Z of a particle at the end of a tracking step is Xx xX vye At R Y Ye WAR 3 28 Z Ze Oh At R The Modeling Environment Processing Modflow 3 31 where Xj Yo Z is the initial position of the particle v h y and v are initial linear velocities evaluated at Xj Yo Z and R is the retardation factor resulting from the incorporation of sorption isotherms into the transport equation Numerical errors tend to be large unless small transport steps Af are used In MT3D At is determined from Atl lt vorm SO Me Me ve where Ax Ay and Az are the widths of the cell in the x y and z directions y is the Courant number 3 29 The fourth order Runge Kutta method is preferred over the first order Euler method because the former is more accurate and permits the use of larger tracking steps At However the computational effort required by the fourth order Runge Kutta method is considerably larger than that required by the first order Euler method
293. se values are best set low If they are set too low however the estimation process can be 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 on this file at the end of each optimisation 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 RELPARMAX and or FACPARMAX could be increased If RELPARMAX and FACPARMAX are set too high the estimation process may fail If PEST seems to be making no progress in lowering the objective function and an inspection of the PEST run record shows that some or all parameters are undergoing large changes at every optimisation The Modeling Environment Processing Modflow 3 49 iteration then it would be a good idea to reduce RELPARMAX and or FACPARMAX Another sign that these variables may need to be reduced is if PEST rapidly adjusts one or a number of parameters to their upper or lower bounds and the latter are set far higher or lower than what you would expect the optimal parameter values to be a further sign is if rather than lowering the objective function PEST estimates parameter values for which the objective function is incredibly high If you are unsure of how to set these parameters a value of 5 for each of them is often suitable In cases of extreme nonlinea
294. select an appropriate menu item from the Run gt Graphs menu The graph viewer Fig 4 22 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 h is the starting hydraulic head and h is the calculated head at time t The coordinates of bores and the corresponding observed data are specified in the Bores and Observations dialog box see section 3 3 6 PMWIN employs a bilinear interpolation scheme to calculate values pertaining to user specified bores from those saved in unformatted binary simulation result files For each user specified bore the four model cells surrounding that bore are first determined The simulation results at those cells are then interpolated to the bore by using the following equation i 1to4 A 0 if h HORY HNOFLOor CINACT 4 16 where A is the area and h is the computed value at the center of a cell as shown in Fig 4 23 HNOFLO and HDRY are predefined heads for no flow cells and dry cells and C NACT is the predefined concentration value for inactive concentration cells If a bore lies in an inactive cell h HDRY Head Time Curves Graph Style Linear Semi Log X Axis Time Y Axis Data Types Data gt gt Min Time Min Value i Calculated 30 20 00919 Ob
295. servation Save Plot As Max Time Max Yalue Opti a ptions jose 18 26 79034 i Draw Horizotal Grid Help 10 10 ix Auto Adjust Min Max Ticks Ticks i Draw Vertical Grid Fig 4 22 The Graph Viewer showing head time curves Modeling Tools 4 32 Processing Modflow The available settings of the graph viewer are summarized below gt The Bore Table The bore numbers and the plot colors are given in the table of the graph viewer The curve of a bore will be displayed only when the corresponding Plot flag is set to YES The plot color of each curve is given in the Color column To change the color double click on the colored cell of the table Note that if you have deactivated a bore in the Bores and Observations dialog box the corresponding row of the table in the graph viewer will be dimmed and you cannot change its settings X Axis 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 of Ticks Y Axis Min Value and Max Value specify the mintmum Y axis value and maximum Y axis value on the graph The number of desired ticks is given in the edit field of Ticks Data Types Check the Calculated or Observation boxes to display the curves based on the computed or observed data The graph viewer uses solid lines for displaying calculated curves Observation curves are dashed
296. soils engineering equations and basic ground water flow equations U S Geological Survey Water Supply Paper 2064 Processing Modflow Konikow L F 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 Kuiper L K 1981 A comparison of the incomplete Cholesky conjugate gradient method with the 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 Math ron G 1963 Principles of geostatistics Economic Geology 58 1246 1266 McDonald M C and A W Harbaugh 1988 MODFLOW A modular three dimensional finite difference ground water flow model U S Geological Survey Open file report 83 875 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
297. sport simulation select the item again and deactivate it If the concentration of a source or sink is not specified the default value for the concentration is Zero 3 3 6 The Estimation Menu The Estimation menu provides an interface between PMWIN the flow model MODFLOW and the parameter estimation program PEST Using PMWIN and PEST the following parameters and or excitations can be calibrated e Horizontal hydraulic conductivity or transmissivity e Vertical hydraulic conductivity or vertical leakance e Specific storage specific yield or storage coefficient e Inelastic storage factor e Pumping rate of wells e Conductance of a drain GHB river or stream cell e Recharge flux e Maximum ET rate Using the Control Data menu you specify the necessary control values for a PEST operation The Parameter List gives an overview of estimated parameters and or excitations An estimated parameter e g transmissivity or pumping rate is defined by using the Zone Input Method of the Data Editor see Define an Estimated Parameter below The bore coordinates and observation values are given in the Bores and Observations Using PEST model parameters and or excitations can be adjusted until model generated numbers fit the observation values as closely as possible That is PEST searches an optimal parameter set for which the sum of squared deviations between The Modeling Environment Processing Modflow 3 45 model generated observations and experi
298. stimation program PEST is used to calculate the necessary pumping rate The aquifer in which the contaminated area is buried consists of one unconfined layer and is of infinite area extent The extent of 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 0 m The hydraulic conductivity is isotropic and uniformly 3x10 m s The unconfined storage coefficient specific yield is about 0 2 Recharge is assumed to be zero The groundwater flow is directed from west to east with a hydraulic gradient of 0 5 c The objective of the remediation measure is to prevent contaminated water flow out of the area Different types and combinations of measures can be introduced for this purpose including a slurry wall around the area drainages and pumping wells An impervious cover could be considered if the recharge were not zero All measures are directed to the same goal a reduction of the piezometric head in the area itself such that the groundwater flow is directed towards the contaminated area To achieve this objective a slurry wall around this area and four pumping wells have been chosen Fig 5 4 shows the configuration of the remediation measures The slurry wall is 0 5 m thick and the hydraulic conductivity of the material is 5x10 m s The configuration of the model is shown in Fig 5 5 To obtain the hydraulic gradient of 0 5 o the west and east si
299. stimation process On the other hand if PHIREDLAM is set too low PEST will test too many Marquardt lambdas on each optimisation iteration when it would be better off starting on a new iteration gt NUMLAM This integer variable places an upper limit on the number of lambdas that PEST can test during any one optimisation 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 this gives PEST a greater chance of adjusting to the reduced problem dimension as parameters are frozen gt RELPARMAX and FACPARMAX There should be some limit placed on the amount by which parameter values are allowed to change in any one optimisation iteration If there is no limit parameter adjustments could regularly overshoot their optimal values causing a lengthening of the estimation process at best and instability with consequential estimation failure at worst the dangers are greatest for highly nonlinear problems PEST provides two real variables which can be used to limit parameter adjustments these are RELPARMAX and FACPARMAX RELPARMAX is the maximum relative change that a parameter is allowed to undergo between optimisation iterations whereas FACPARMAX is the
300. t layer relative to the same datum as the heads If the first layer is unconfined HTOP can be set most conveniently to a uniform elevation above the water table Note that the concentration for cells in the first layer is calculated at nodes assumed to be midway between HTOP and the bottom of the first layer HTOP should not be set much higher than the water table If the first layer is confined then HTOP is equal to the bottom elevation of the confining unit overlying the first layer is the cell thickness in each layer DZ is a three dimensional array The input to three dimensional arrays is handled as a series of two dimensional arrays with one array for each layer entered in the sequence of layer 1 2 NLAY The thickness of the first layer should be entered as the difference between HTOP and its bottom elevation is the effective porosity of the porous medium for each cell of the grid is the boundary indicator array for the concentration field If ICBUND 0 the cell is an inactive concentration cell Note that noflow or dry cells are automatically converted into inactive concentration cells Furthermore active 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 If ICBUND lt 0 the cell is a constant concentration cell The initial concentration remains the same at the cell throughout the si
301. ted in the same way as CRIV of the River Package see Equation 3 11 Stream Channel Properties are used only when the option Calculate stream stages in reaches is chosen Stream width is the width of the rectangular stream channel Stream Slope is the slope of the stream channel in each reach Manning s roughness coeff C is the result of the dimensionless Manning s roughness coefficient divided by a constant C Some of the experimental values of the dimensionless Manning s roughness coefficient can be found in the documentation of the STR1 Package The value of the constant C depends on the length and time units of your model Ns nL n ne Mm Fs Vago E 71080 1 1574 107 S S d Cad 3 12 Stream Structure describes the configuration of the stream system Each row in the table represents a stream segment in the model Each segment can have up to 10 tributary segments The number 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 13 indicate that segment 2 is diverted from segment 1 segment 1 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 14 The Modeling Env
302. tep 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 is the 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 DTO is the length of transport steps If DTO 0 the length of transport steps will be determined by an automatic stepsize control procedure in MT3D MXSTRN is the maximum number of transport steps Appendix A 6 Processing Modflow Trace File A Trace ile can be saved or loaded by the Search and Modify dialog box see section 3 3 7 File Format Ls Data LABEL The following data repeats 50 times one record for each search range Ba 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 re
303. tes 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 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 The File Table PMWIN uses the user specified data to generate input files of MODFLOW and PEST The Description column gives the name of the packages used in the flow model The path and name of the input file are shown in the Destination column PMWIN generates an input file only if the Generate flag is set to YES You can click on a row to toggle the Generate flag between YES and NO Generally you do not need to worry about these flags as PMWIN will care about the settings See Appendix 7 for the names of the generated input files of MODFLOW and PEST gt Options e 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 or you want to run another model saved in the same subdirectory as the current model e Generate input files only don t start PEST Check this option if you want to run PEST outside of Windows for example you want to use PESTEM See OK below for how to run PEST outside of Windows e Perform PESTCHEK prior to running PEST PESTCHEK reads the PEST input files generated
304. tes a volumetric water budget for the entire model at the end of each time step and saves it in the record file see Fig 2 8 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 the total change in storage It is recommended to read the record file or at least glance at it The record file contains other further essential information In case of difficulties this supplementary information could be very helpful 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 Table 2 1 Output files from MODFLOW VOLUMETRIC BUDGET FOR ENTIRE MODEL AT END OF TIME STEP 1 IN STRESS PERIOD 1 CUMULATIVE VOLUMES L 3 T RATES FOR THIS TIME STEP LA 3 7 IN IN STORAGE 0 00000 STORAGE 0 00000 CONSTANT HEAD 0 68083E 01 CONSTANT HEAD 0 68083E 01 WELLS 0 00000 WELLS 0 00000 TOTAL IN 0 68083
305. th assigned constant head of 25 column 1 2 3 4 recharge cells Plan View 40 infiltration po modeled quarte Fig 5 16 Hydrogeology and model grid configuration Simulation Results 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 see equation 3 24 to head only in underlying cells which is indicated by a negative value of THRESH The wetting iteration interval is 1 and THRESH is 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 Applications and Sample Problems Processing Modflow 5 19 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 is generally much larger than the head difference between adjacent vertical cells along the mound For example the cell at layer 4 row 3 column 4 is 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 diffe
306. the corresponding bore number will be shown on the screen by the Data Editor Fig 3 35 For transient simulations PMWIN The Modeling Environment Processing Modflow 3 59 interpolates the simulation results to the active bores and you can use the Graphs see Chapter 4 menu to see the time related line graphs e g Head time curves In Table of Observations you specify the bore number in the Bore column The observation time is given in the Time column This is the time measured from the start of the model simulation to which the measured head drawdown concentration compaction preconsolidation head and subsidence value pertains Using the Graph Viewer see Chapter 4 you can create line graphs based on the observation values Note that drawdown is defined by h h where h is the starting hydraulic head and h is the measured head at the observation time Using the buttons Save and Load you can save or load the contents of the tables in or from a Bore file or Observation file The format of these files is given in Appendix 2 You can insert or delete a row of the tables by pressing the Ctrl Ins or Ctrl Del key In PMWIN the maximum number of bores is 1000 The maximum number of observations is 6000 For the model calibration PEST uses the observed head or drawdown values only when the observation times correspond to one of the simulation times at which MODFLOW writes the simulation results to its unformatted binary files
307. 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 in the format 15 1X 5 E20 12 1X 2 13 1X 13 The variables in the order of appearance on the line are defined as 1 Particle index number The index number is 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 K index of cell containing the point sree Sy Or eee a Modeling Tools Processing Modflow 4 17 Except the particle index number this format is identical to the PATHLINE FILE format described in the program documentation of MODPATH gt 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 th
308. the log of its value Experience has shown repeatedly that log transformation of at least some parameters can make the difference between a successful parameter estimation run and an unsuccessful one This is because in many cases the linearity approximation on which each PEST optimisation iteration is based holds better when certain parameters are log transformed However caution must be exercised when designating parameters as log transformed 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 however 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 is 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 is 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 optimisation process PARTRANS must be supplied as Fixed If a parameter is linked to another parameter this is signified by a PARTRANS value of Tied In the latter
309. the net volume of water from interbed storage in the volumetric budget of the model would directly relate to total compaction for half of the doubly draining bed A cell width of 0 25 m was selected thereby requiring 20 finite difference cells to represent onehalf of the doubly draining bed An additional cell was required to impose the specified head boundary condition of cyclical ramp loading T T S N unit area 1 m x 1m gt k 0 25m Fig 5 29 Configuration of the finite difference grid after Leake and Prudic 1991 In the original MODFLOW by McDonald and Harbaugh 1988 the only provision for changing specified head at boundary cells is by use of the River Package Drain Package or General Head Boundary Package Those packages allow specification of a different boundary head at each stress period If associated river bed conductances are large enough the head in the aquifer will almost equal the boundary head For the ramp load problem difficulties may arise from using these packages to approximate a specified aquifer head First the flow from the boundary to the aquifer is computed as the product of conductance and head difference between the boundary and the aquifer If the intent is to make that difference small mass balance errors result because of imprecision in computing the head difference across the boundary Precision is lost when two nearly equal numbers are subtracted Second a large amount of i
310. tion If a parameter is 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 see the Run Menu To the right of the sign of each prior information equation are two real variables viz PIVAL and WEIGHT The former is the value of the right side of the prior information 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 about the prior information 1 0 log P1 1 2 log P2 5 6 1 0 1 0 P1 1 455 P2 3 98 P3 2 123 P4 1 03E 3 2 00 2 12 P3 3 2 P6 1 344 2 20 Bores and Observations In the Bores and Observation dialog box Fig 3 34 you specify the eastings x northings y and layer numbers of each bore in Table of Bores A bore is active if the Active flag in the table is set to YES When you edit model data active bores and
311. tions were reached at the 44th time step of the transient simulation as indicated by storage flow terms being zero see the simulation record file OUTPUT DAT Simulated Water Table are N Water table priar to pond leakage N A D A D D B O B S S S S S D S S B ppp B S S S S S S B S S S B B S B 1000 2000 3000 4000 5000 Distance from center of pond in feet Steady State 190 days isn 708 days 2630 days Fig 5 17 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 Applications and Sample Problems 5 20 Processing Modflow 5 8 Simulation of a Perched Water Table Location PMWIN EXAMPLES BCF2 EX3 Problem Description and Modeling Approach Contrasts in vertical hydraulic conductivity within the unsaturated zone can provide a mechanism for the formation of perched ground water tables This example is from the third test problem of the BCF2 Package It simulates formation of a perched water table and has practical application in the simulation of recharge going to a deeper aquifer system The conceptual model is rectangular and consists of three geohydrologic units The upper and lower units have higher hydraulic conductivities than the middle unit Fig 5 18 There is a regional water table in which the head is below the bottom of the middl
312. to a single cell within a vertical column of cells There is no need to allow for recharge to occur simultaneously at multiple depths in the same vertical column because natural recharge enters the groundwater system at the water table In the simplest situation the water table is located in the top layer of the model The top layer is designated as unconfined and an array of Recharge Flux is specified The Modeling Environment Processing Modflow 3 23 for that layer Problems may arise when the water table cuts across layers To solve this kind of problems the RCH1 Package provides three options for specifying the cell in each vertical column of cells that receives the recharge 1 Recharge is only applied to the top grid layer 2 Vertical distribution of recharge is specified in the Layer Indicator Array Ipc 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 is automatically selected by the RCH1 Package If the highest active cell is a constant head cell recharge will be intercepted and cannot go deeper Evapotranspiration EVT1 The Evapotranspiration Package simulates the effects of plant transpiration and direct evaporation in removing water from the saturated groundwater regime The EVT1 Package requires the user to assign the following data for each EVT cel
313. tor that is included in the calculation of the head that is initially established at a cell when it is converted from dry to wet See IHDWET is the iteration interval for attempting to wet cells Wetting is attempted every WETIT iterations If using the PCG2 solver Hill 1990 this applies to outer iterations not inner iterations If IWETIT is 0 it is changed to 1 is a flag that determines which equation is used to calculate the initial head at cells that become wet f IHDWET 0 h BOT WETFCT hn BOT f IHDWET 0 h BOT WETFCT THRESH is the layer type table Each element holds the code for the respective layer Read one value for each layer There is a limit of 80 layers If there are 40 or fewer layers use one record otherwise use two records Leave unused elements in a record blank LAYCON 0 confined layer Transmissivity and storage coefficient of the layer are constant for the entire simulation LAYCON 1 unconfined layer Transmissivity of the layer varies It is calculated from the saturated thickness and hydraulic conductivity The storage coefficient is constant This type code is valid only for layer 1 LAYCON 2 confined unconfined layer Transmissivity of the layer is constant The storage coefficient may alternate between confined and unconfined values Vertical flow from above is limited if the layer desaturates LAYCON 3 confined unconfined layer Transmissivity of the layer varies It is calculat
314. tour maps The gridded information or the digitized maps will be overlaid on the model grid for assigning parameter values to model cells The process is indirect and somewhat cumbersome PMDIS 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 program takes measurement data and interpolates 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 Using the Data Editor you can create contour maps of the interpolation results and visually choose a best result See section 6 11 for an example Theory is not emphasized in this description because it is introduced in an extensive literature For example 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 computer graphics techniques Akin and Siemes 1988 and Davis 1973 provide necessary mathematical background skills on the Statistics and data analysis in geology PMDIS runs independently from PMWIN To start PMDIS select Field Interpolator
315. two records 3 Data TRPY NLAY Input Module U1DREL 4 Data DELR NCOL Input Module U1DREL 5 Data DELC NROW Input Module U1DREL A subset of the following two dimensional arrays is used to describe each layer The arrays needed for each layer depend on the layer type code LAYCON whether the simulation is transient ISS 0 or steady state ISS 0 and if the wetting capability is active IWDFLG 0 If an array is not needed it must be omitted In no situation will all arrays be required The required arrays Data 6 13 for layer 1 are read first then the arrays for layer 2 etc IF THE SIMULATION IS TRANSIENT ISS 0 6 Data sf1 NCOL NROW Input Module U2DREL IF THE LAYER TYPE CODE LAYCON is 0 or 2 hs Data Tran NCOL NROW Input Module U2DREL IF THE LAYER TYPE CODE LAYCON IS 1 or 3 8 Data HY NCOL NROW Input Module U2DRE Oe Data BOT NCOL NROW Input Module U2DR lb IF NOT THE BOTTOM LAYER l0 Data Vcont NCOL NROW Input Module U2DREL IF THE SIMULATION IS TRANSIENT ISS O AND TH ll Data sf2 NCOL NROW Input Module U2DR Fi LAYER TYPE CODE LAYCON IS 2 OR 3 za Li IF THE LAYER TYPE CODE LAYCON IS 2 OR 3 l2 Data TOP NCOL NROW Input Module U2DREL IF THE LAYER TYPE CODE LAYCON IS 1 OR 3 AND THE WETTING CAPABILITY IS ACTIVE IWDFLG IS NOT 0 13 Data WETDRY NCOL NROW Input Module U2DREL Explanation of Parameters Used in Input Instructions Is
316. 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 1 and column 1 are no flow as a result of the symmetry A constant head boundary of 25 feet 7 62 m is specified along row 40 and column 40 for layers 10 14 a no flow boundary is 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 3 see section 3 3 4 is used so that recharge will penetrate through inactive cells down to the water table The recharge rate of 0 05 foot per day 0 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 5806 m Applications and Sample Problems 5 18 Processing Modflow Model Grid Configuration Cross Section z 3 infiltration pond mo imi 2 70 pond leakagelV V layer1 E 60 rt 2 a N 3 o 50L 5 1 2 Groundwater moun 7 5 2 404 6 S 4 N 8 amp 30 Watertable HE ep er 9 HHL 10 20 l l l 7 2 ratio of horizontal to vertical T S 10F hydraulic conductivity is 20 to 1 a oY u o 14 Cells wi
317. vate the Environment Options dialog box Minimum and Maximum are set to the lower and upper limits of the cell data Different contour levels can be obtained by changing the values of Maximum Minimum and Interval The data of inactive cells will not be used if Ignore Inactive Cells is checked For particular packages in which a cell has more than one value e g River Package the Parameter drop down box contains the available parameter type s The Data Editor creates contours based on the cell data of the selected parameter type gt Maps The Maps Options dialog box Fig 3 46 allows you to display up to 5 background DXF maps A DXF file contains detailed data describing numerous CAD entities An entities 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 DXF File x Y Factor Ex HApmwin examples pmex map 2000 00 l 2000 00 l 13 100 C Bi apmwin examplesipmexiexan 0 00 0 00 1 000 Click the right mouse button on the DXF file fields to select files Help Cancel OK Fig 3 46 The Maps Options dialog box The Modeling Environment 3 68 Processing Modflow e To import a DXF map 1 Click the right mouse button on any of the five DXF file edit fields and select a DXF file from
318. vered by the pond Elevation in feet above arbitrary datum Cross Section Model Grid Configuration infiltration pond 60 Moo Pitti ty VW WW WW INN pond leakage 507 Perched groundwater mou Layert 40 307 NA SERRA ii 207 Vertical Leakanc 107 Layer 2 0 Assigned constant head of 1 fi 1 Column 16 cell dimensions 16 ft by 16 ft recharge cell Plan View 50 infiltration po modeled quarte Fig 5 18 Hydrogeology and model grid configuration Applications and Sample Problems 5 22 Processing Modflow Simulation Results 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 The steady state simulation produced the long term head distribution resulting from the pond recharge 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 Wetting and SIP solver parameters are adjusted to obtain a solution The wetting iteration interval THRESH see equation 3 24 and wetting factor are set at 2 iterations 1 0 foot and 0 5 respectively A positive value of THRESH indicates that horizontally adjacent cells can cause dry cells to become wet This is the
319. vironment Options dialog box check the Visible check box of the Contours group click the color button next to the Visible check box to select an appearance color of the contours Note that PMWIN will uncheck the Visible check box if you leave the Editor or move to other layers In the Environment Options dialog box Click OK PMWIN will redraw the model and display the contours Fig 2 15 To save the graphics choose Save Plot As from the File menu and specify a plot format and file name in the Save Plot As dialog box Fig 2 16 Press PgDn to move to the second layer Repeat steps 2 to 9 to load the file H2 DAT display and save the plot Your First Groundwater Flow Model with PMWIN 2 16 Processing Modflow Parameter Column Width Recycle gt fi 4 Load Save Cancel OK Fig 2 12 The Browse Matrix dialog box with the cell values in the spreadsheet 11 Choose Leave Editor from the File menu or click the Leave Editor icon and click Yes to save changes to Recycle Using the foregoing procedure you can generate contour maps of your input data 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
320. w 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 To bypass this possibility an absolute lower bound can be placed on parameter increments this lower bound will be the same for all group members and is provided as the input variable DERINCLB Thus if a parameter value is currently 1000 0 and it belongs to a group for which INCTYP is Relative DERINC is 0 01 and DERINCLB is 15 0 the parameter increment will be 15 0 instead of 10 0 calculated on the basis of DERINC alone If you do not wish to place a lower bound on parameter increments in this fashion you should provide DERINCLB with a value of 0 zero Note that if INCTYP is Absolute DERINCLB is ignored e FORCEN can be Always_2 Always_3 or Switch It determines whether derivatives for group members are calculated using forward differences one of the variants of the central difference method of whether both alternatives are used in the course of an optimisation run If FORCEN for a particular group is Always_2 derivatives for all parameters belonging to that group will always be calculated using the forward difference method As described in the section 2 3 1 of the PEST manual filling of the columns of the Jacobian matrix corresponding to members of the group will require as many model runs as there are adjustable parameters in the group If FORC
321. 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 Type 4 Layer of type 0 a quasi 3D confining layer Type 5 Layer of type 1 a quasi 3D confining layer The Modeling Environment Processing Modflow 3 11 Type 6 Layer of type 2 a quasi 3D confining layer Type 7 Layer of type 3 a quasi 3D confining layer The last four types are only used by MODPATH for quasi three dimensional models in which aquifer layers are separated by intervening semi confining units A confining unit does not need to be simulated as active layers in finite difference models The effect of a confining unit can be simulated by means of a transmission term named vertical leakance between two model layers For transient simulations release of water from storage within the unsimulated confining unit is not considered Use the Interbed Storage Package IBS1 Leake and Prudic 1988 if you need to consider the changes in storage for transient simulations To calculate pathlines in MODPATH each unsimulated confining unit is assumed to be a part of the active model layer directly above it It is assumed that one dimensional steady state vertical flow exists throughout the confining layer This assumption implies that the average vertical linear velocity is constant in the confining unit and that its magnitude equals the volumetric flow rate b
322. y as the order reaches are read into the program determines the order of connection of inflows and outflows is the streamflow in length cubed per time 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 is the sum of outflow from a specified number of tributary segments the segment inflow values are specified as a 1 Note if the specified inflow to a diversion is greater than the flow in the reach from which flow is to be diverted then no flow is diverted from the stream is the stream stage in units of length is the streambed hydraulic conductance in units of length squared per time is the elevation of the bottom of the streambed in units of length is the elevation of the top of the streambed in units of length is the width of the stream channel in units of length It is used only when stream stage in each reach is calculated is the slope of the stream channel in each reach in units of length pre length It is used only when stream stage in each reach is calculated is Manning s roughness coefficient for each stream reach It is used only when stream stage in each reach is calculated for a segment that has tributary segments Itrib 1l is the number of the first tributary segment For a segment with no tributary Itrib 1 must be specified as zero for a segment that has tributary segme
323. y zones in the cell by cell mode L visible Ignore Inactive Cells Horizontal Hydraulic Conductivity Min 7 55165E 05 Interval 4 032524E 0 Fig 3 45 The Environment Options dialog box The Modeling Environment Processing Modflow 3 67 Grid Appearance allows you to change the visibility and appearance color of each simulated hydraulic elements A simulated hydraulic element is visible if the corresponding check box is checked To select a new color click the colored button next to the check box and select a color from the Color dialog box Grid Position and Worksheet Size define the coordinates system of your model The size of the worksheet is defined by the lower left and upper right corners of the worksheet i e by the coordinates X Y and X Y as shown in Fig 3 45 Using the rotation angle and the coordinates Xp Yo of the left upper corner of the model grid you can rotate and place the model grid at any position The rotation angle is expressed in degrees and is measured counterclockwise from the positive x direction Contours The Data Editor displays contours based on the cell data if the Visible box is checked To select a new color click the colored button next to the check box and select a color from the Color dialog box The contour interval is automatically chosen such that 11 contours from the lower limit Minimum to the upper limit Maximum of the cell data are displayed Each time you acti
324. yer with constant transmissivity layer type 2 see section 3 3 2 The top and bottom 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 but the perched heads have a direct impact on the recharge into the lower layer The purpose of the simulation is to show that the distribution of recharge from the perched system can be estimated by using the BCF2 Package to simulate the perched water table 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 affects are negligible This unit is represented by the value for vertical leakance see section 3 3 3 between model layers 1 and 2 The vertical leakance is assumed to be 0 0002 per day In areas not covered by the pond recharge is applied areally at a rate of 0 001 Applications and Sample Problems Processing Modflow 5 21 foot per day to simulate natural recharge Recharge option 3 see section 3 3 3 is used so that recharge will penetrate through inactive cells to the water table A recharge rate of 0 01 foot per day is applied to the area co
325. ype C PMWIN DATA MPATH30 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 Processing Modflow Appendix 7 Input data files of the supported programs The input data files created by PMWIN for each packages of the supported programs the model directory and listed below MODF LOW Basic Package BAS D Block Centered Flow Package BCF1 or BCF2 BCF D River Package RIV D Recharge Package RCH D Well Package WEL D Drain Package DRN D Evapotranspiration Package EVT D General Head Boundary Package GHB D Strongly Implicit Procedure Package SIP SIP D Slice Successive Overrelaxation Package SSOR SOR D Preconditioned Conjugate Gradient 2 Package PCG2 PCG2 Stream Routing Flow Package STR1 STRI Interbed Storage Package IBS1 IBS1 Horizontal Flow Barrier Package HFB1 HFB1 Time Variant Specified Head CHD1 CHD1 Output Control OC DA MODPATH and MODPATH PLOT version 1 x Main data file MAIN MODPATH and MODPATH PLOT version 3 x Main data file MAIN3 Other files required by MODPATH such as RIV DAT or WEL DAT are the same as those of MT3D Basic Transport Package MTBTN Advection Package MTADV Dispersion Package MTDSP Sink amp Source Mixing Package MTSSM Chemical Reaction Package MTRCT PEST Instruction File INSTR Control File PESTC Block Centered Flow Package Template File BCFTP River Package Tem

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