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TUTORIALS Volume II GMS version 5.0

1. Figure 94 Placement of Vertices 7 Click out a set of scatter points similar to those shown in Figure 9 4 Create about 15 points Don t worry about the exact location of the points as long as they are distributed in a reasonable fashion 9 17 Entering the HK parameter In our previous example we had four hydraulic conductivity parameters For this problem we are estimating the hydraulic conductivity for the entire layer with pilot points Therefore we only need one parameter for hydraulic conductivity This parameter will then be linked to the pilot points using the Parameters dialog 9 17 1 Creating One Parameter Zone We will change the values that we have assigned to the polygons so that there is only one hydraulic conductivity parameter 1 Switch to the Map module 2 Select the Hydraulic Conductivity coverage from the Data Tree Automated Parameter Estimation 9 13 Select the Select Polygon tool Double click on each of the polygons the coverage and change the value of the Horizontal input field to 100 Select the Feature Objects Map gt MODFLOW MODPATH command to convert the concep
2. 5 2 5 6 DEFINING THE STARTING 8 2 2 2 2 2 2 1 0 0000600000000000000000000000 500000 0 5 3 5 6 1 Viewing the Pathlines in Cross Section 5 4 5 7 DISPLAY OPTIONS 5 4 5 8 PAR EIGEE SETS E E TE 5 4 2S Particle 1 5 5 3 8 2 Duplicating Parnell Sets dks gee aad AER weed 5 5 36 3 Changing the Display Ordet seriis e 5 6 5 9 TRACKING PARTICLES FROM THE 2 2 2 2 2 10 02 80000000000000000004000000000000000000000 5 6 5 9 1 Creating a New Particle 8 5 6 5 9 2 Defining the New Starting 5 6 5 10 BY ZONE CODE beatae 5 7 Soil SPATHEINE SENG TH TIMB Ss 5 eae 5 8 22 CAPTURE ZONES BY 5 8 213
3. 11 13 12 STOCHASTIC MODELING PARAMETER 244 1 0 0010 4 4 0 12 1 12 1 DESCRIPTION OF PROBLEM 1 1060000000 0000000 000000000500 12 2 122 RANDOM SAMPLING VS LATIN 2 40 0 000 0 06000000000 000 12 2 12 3 GETTING 12 3 1247 12 4 12 5 READINGIN THE PROJECT peirin 12 4 12 67 12 4 12 7 DEFINING THE PARAMETER 70 8 20022 22 20404 00000010000000000000000000005000550 12 4 12 7 1 Setting up the Recharge 12 5 12 7 2 Setting up the Hydraulic Conductivity Zone 12 6 12 7 3 Mapping the Key Values to the Grid 12 6 12 8 SELECTING THE STOCHASTIC OPTION ccccccesssscecssssececeeseecsesseeecsesaececseeeecsesseeecsesaeesseeseesssseseeseaaes 12 6 12 9 EDITING THE PARAMETER 4 4 2 0004 0020200460 4000005000000 50000080000000 12 6 12 10 SAVING THE PRO
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5. tes 5 9 6 MT3DMS GRID APPROACH 25565659 6 1 6 1 DESCRIPTION OF PROBLEM 5 22 6 1 6 2 GETTING STARTED iesin eieiei iE R EEEa ia EEEE E rA EEA SEEE EEE 6 2 6 3 REQUIRED MODULES INTERFACES ccscccssssesssecssecsececssecsececsaeceeeecsseceseeecsseceseeecsaeceeeeesseceeeeesaeensees 6 2 6 4 THE FLOW MODEL 6 3 6 5 A 6 3 6 5 1 Initializing the 51 1 6 3 6 5 2 The Basic Transport Package 6 4 6 5 3 The Advection Package 6 5 65 4 IheDispersion Packa te moies netar 6 6 6 5 5 Source Sink Mixing 6 6 6 5 6 Saving the Simulation and Running 3 6 6 6 5 7 Changing the Contouring 6 7 6 5 8 Setting slash candeasioes 6 7 6 6 OILE AOSTO e EEE 6 7 7 MT3DMS CONCEPTUAL MODEL 20
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8. 8 11 8 135 ERROR VS SIMULATION PLOT succeed EE AE E EE E EE E 8 11 8 14 CONTINUING THE TRIAL AND ERROR CALIBRATION 1 20000 0 000000000000 8 11 8 14 1 Changing Values vs Changing Zones 8 12 8 14 2 Viewin the 8 12 82197 amp 2 2 2 8 12 AUTOMATED PARAMETER ESTIMATION csscsssssssssssssccssessssssssssssscssnscssssccsnessssssssnessssssess 9 1 9 1 DESCRIPTION OF PROBLEM cssccessssecesssnsecsssaeeesesssecsessusecseseeessesssecsesessecsesaeessessseceesassecsesaeeeseeaaees 9 1 9 2 GETTING STARTED Hole Se A ic ced 9 2 9 3 REQUIRED MODULES INTERFACES 50 csc cossesvaiscsentevevsedenavssecessnveedsacedhecdestesedecsssceeseeevsnieedeteedstes 9 2 9 4 READING IN THE cases selene 9 2 9 5 MODEL PARAMETERIZATION cssccccssssecesssececsssseeecenseecessneeecsesaececsessecsesaeeecsesaesecsesaessesueeessesaeeeceeaaees 9 3 9 6 DEFINING THE PARAMETER ZONES c cccssssssecsesseeeceescecessneeecsessececeessecessaesecsesaeseceeaaeesseeeessesaeeecenaaees 9 3 9 6 1 Setting up the Hydraulic Conductivity 7 9 3 9 6 2 Setting up the Recharge Zones eei Cors
9. 9 14 9 19 EE R Tai 9 14 9 20 VIEWING THE FINAL HYDRAULIC CONDUCTIVITY 2 2 2 2 20 00 000000000 9 15 9 16 REGIONAL TO LOCAL MODEL CONVERSION u scsssscssssssssscsssscsssscssessssscsssesssssssssessssssess 10 1 10 1 DESCRIPTION OF PROBLEM cccssssssesssscecsesececseseececsneeecsesaeeeceesaeeecseeecsesaececseceeceesaeeesseaeeeseeaeeeess 10 1 10 22 GETTING STARTED ade Sis 10 3 10 3 REQUIRED MODULES INTERFAGES 10 3 10 4 READING IN THE REGIONAL MODEL c cccsssssseesescesesssececseaececeneceseesaeeecsesaeeecseeeeessaeeecsesaeeeeneeeenes 10 3 10 5 CONVERTING THE LAYER DATA A SCATTER POINT SET ccccccsesssscecseseeeeceeececessneeecsesaeeeeneeeeeees 10 4 10 6 APPROACH TO BUILDING THE LOCAL 22 2 2 2 2 200000000000000000000000000000000000000000000 10 4 10 7 BUILDING THE LOCAL CONCEPTUAL 2 2 1 2 02 0000000000000000000000000000000 10 4 10 7 1 Creating New 10 4 10 7 2 Creating the AFOS
10. Figure 3 6 Image Registration 37 Defining the Units At this point we can also define the units used in the conceptual model The units we choose will be applied to edit fields in the GMS interface to remind us of the proper units for each parameter 1 Select the Edit Units command 2 For Length select m for meters For Time select d for days We will ignore the other units they are not used for flow simulations 3 Select the OK button 3 8 Creating the Conceptual Model We are now ready to enter our model data First we will create a MODAEM conceptual model Then we will create coverages to define the boundary conditions and aquifer properties The boundary of our model is shown in the following figure N 1 Switch to the Map module MODAEM 3 11 2 Right click the Data folder in the Data Tree and select New Conceptual Model option 3 Change the name to Indiana and the model to MODAEM and click OK 4 Right click on Indiana and select the New Coverage option 5 Change the name to Boundary and select the Use to define model boundary Click OK 6 Select the Zoom tool 7 Zoom in around the model area by dragging box that encloses the area shown in Figure 3 7 below 8 Select the Create Arc tool 9 Click out the boundary as shown in Figure 3 7 below PAFU 1 522 Figure 3 7 Boundary Arcs 3 12 3
11. a iA rin eE E Ea EEE 10 5 10 7 3 Building the Polyoni ka dics tee aaa 10 6 10 7 4 Marking the Specified Head 10 6 10 8 CREATING THE LOCAL MODFLOW 10 7 10 8 1 Creating the Grid cls ASA 10 7 10 8 2 Activating the Cells bes ote ae eae 10 8 10 8 3 Mapping the 10 8 GMS Tutorials Volume 10 9 THE LAYER DATA ccccccsssseceessececesaececsescecessaeeecsssaececsaeeseesaeeecsesaeesceseeeesaeeeeneaaes 10 8 10 10 SAVING AND RUNNING THE LOCAL MODEL ssssssesessseeecssececeessececseseeeecsueeeceeaeeecseeaeeseneeeeeeees 10 9 10 11 CONGEUSION Fes E E E 10 9 11 MANAGING TRANSIENT DATA cs ceitcicnsscoctsscodsssnuessescesscessesensestoneedosdssoncesendessec ensasoncccescesenseseeses 11 1 11 17 DESCRIPTION OF PROBLEM he aoe see ok ee BN 11 1 11 2 GETTING STARTED 2 11 2 11 3 REQUIRED MODULES INTERFACES cccccsssscessceesseceeceeseeceseeecseecseeeessecseeeeseeceueeseseecaeseeseecsaeeeesaeces 11 2 11 4 READINGIN THE PROJEGT 2 05 odes salads
12. 3 14 3 13 20 3 15 3 14 RUNNING MODAEM 3 16 3 15 3 17 316 eae eo 3 17 3 172 PRODUCTION WELES 3 17 3 18 OBSERVATION WELDS Meee ieee 3 18 319 3 19 2 20 lt 55 he 3 19 MODFLOW CONCEPTUAL MODEL 4 4 0 12 4 1 4 1 DESCRIPTION OF PROBLEM cccssssscessssceceeseececseececessececseaaesecsneeecsesaeeecsessesecsseeecsesaeeeceeseeeseseeeeneaaes 4 1 4 2 vied be 4 3 43
13. 11 2 14 5 TRANSIENT DATA STRATEGY 11 2 11 6 ENTERING TRANSIENT DATA IN THE MAP 11 3 11 6 1 Assigning the Transient Recharge Rate 11 3 11 6 2 Importing Pumping Well 11 5 11 6 3 Assigning Specific Yield ccccesccccssccscssscsseesceseeseesecseeecsceesceseesceaecseeseeseesessecaeseecaaeeeeeaeesesaeentees 11 6 11 7 INITIALIZING MODFLOW STRESS 0 7 11 7 11 7 1 Changing the MODFLOW Simulation to Transient 11 7 11 7 2 Seting Up the Stress 11 8 11 8 CONVERTING THE CONCEPTUAL MODEL 2 4 4 0 0404020000000 11 8 11 9 SETTING STARTING HEADS NEA E E T E T E 11 9 11 10 SAVING AND RUNNING 2 2 8422 024004060000 11 9 11 11 TRANSIENT OBSERVATION 11 10 11 1111 Importing Transient Observation 11 10 11 11 2 Observation Data File 11 10 11 11 3 Creating Transient Observation Plots 11 11 11 12 CONGLUSION 2
14. 4 3 44 IMPORTING THE BACKGROUND 4 3 44 1 Reading the IMAGE 4 3 4 5 SAVING THE PROJECT EE R iien 4 4 4 6 DEFINING THE UINIVS N 4 4 4 7 DEFINING THE BOUNDARY 4 ads 4 4 4 71 Create the Coverage aes 4 5 7 25 CROALEAN OAR C3 E EPEE EEE 4 5 4 8 BUILDING THE LOCAL SOURCE SINK 2 42 0 2 2 1 00 0010000000000000000000000000005050 4 6 4 8 1 Defining the Specified Head 4 7 48 2 Defining theDrain ALCS dee gia tae inn 4 8 4 8 37 Building th POlyGONs n ra r aa AAG ehh 4 10 Creatine the a aa E aE eE 4 11 4 9 DELINEATING THE RECHARGE 7 8 22 4 4020000 0000000000000000000000000000000000000003 4 12 4 9 1 the Boundary oeoo E E EEEE EE EA EE A 4 12 492 Creating the Landfill 4 12 259 3
15. basic steps for doing Regional to Local model conversion in GMS are 1 Generate the regional model and compute a solution 2 Use the MODFLOW Layers gt 2D Scatter Points command to create the scatter point set with the layer and head data from the regional model 3 Create the 3D grid for the local scale model 4 Interpolate the heads and layer data values from the scatter points to the MODFLOW layer arrays for the local scale model 11 Managing Transient Data Building a transient simulation typically requires the management of large amounts of transient data from a variety of sources including pumping well data recharge data river stages and water levels in observation wells Gathering and formatting such data can be very tedious Fortunately GMS provides a powerful suite of tools for inputting and managing transient data These tools allow all data to be managed using a date time format that eliminates much of the extra data processing that is often required with modeling projects This tutorial illustrates how these tools are used This tutorial is based on the MODFLOW model It is recommended that you complete the MODFLOW Conceptual Model Approach tutorial prior to beginning this tutorial Although this particular model is based on MODFLOW the tools associated with transient data are designed as general purpose tools and can be used with other models 11 1 Description of Problem The m
16. 5 Select the OK button to exit the Stress Periods dialog 6 Select the OK button to exit the Global Package dialog 11 8 Converting the Conceptual Model Now we will convert our conceptual model data to MODFLOW input data 1 Switch to the Map module 2 Select the Feature Objects Map gt MODFLOW MODPATH command 3 Select OK at the prompt Managing Transient Data 11 9 11 9 Setting Starting Heads For transient models you should either set the starting heads equal to the solution generated from a steady state model or allow some time in the beginning of the transient model for the heads to stabilize before applying any changes in stresses pumping rates recharge rates etc We ll take the first approach 1 2 Switch to the 3D Grid module Select the MODFLOW Global Options command Click the Starting Heads button Click the 3D Data Set gt Grid button In the solution tree expand the start MODFLOW solution and select the start_Heads data set Click OK Click OK twice more to exit all dialogs 11 10 Saving and Running MODFLOW We are now ready to save the model and launch MODFLOW 1 2 Select the File Save As command Enter trans1 gpr for the file name Make sure the Save simulations in project folder using project filename option is on Select the Save button Select the MODFLOW Run MODFLOW command Once MODFLOW has finished select the Close button to close
17. 7 10 752074 SRIUN ORTIONS E E 7 11 7 21 SAVING THE SIMULATION 7 11 9227 RUNNING MTIDM Rootes 7 11 7 23 VIEWING THE 5 7 12 7 24 GENERATING A TIME HISTORY PLOT occisis iieii eiiie ii eiiiai 7 12 7 24 1 Creating a Time Series 7 12 75 23 eee Aull So teed dete Seth 7 12 8 MODEL CALIBRATION bisssiscssscsssissceesssivenssssassvesssssacseosestbaseosecoseassuetessosssotecdsostesoeshsutsesseabesbestenssonuesoeds 8 1 8 1 DESCRIPTION OF PROBLEM i 8 1 8 2 GETTING STARTED 8 3 8 3 REQUIRED O 8 3 8 4 gt 8 3 8 5 OBSERVATION DATA i iaa 8 4 8 6 ENTERING OBSERVATION POINTS 2 4 2 00 2 2220000000000000000000000005500
18. 7 1 7 1 DESCRIPTION OF PROBLEM 2 2 1 00000 0001200000000000000000000000000000000000 7 1 viii GMS Tutorials Volume II 7 2 GETTING tne ees 7 1 7 3 REQUIRED MODUEES INTERFACES 22 7 2 7 4 IMPORTING THE PROIECT e 7 2 7 5 DEFINING THE 8 7 2 7 6 INITIALIZING THE MT3DMS 6 7 2 AOL Defining 7 3 20 2 Defining the Stress 1 7 3 7 6 2 7 Selecting Output CON OL sis sists seas oa dias ata asthe cs 7 3 76 0 Selecting the PACKAGES a eA 7 4 7 7 ASSIGNING THE AQUIFER PROPERTIES sc cccssssscessssceeeessececeeseececseeeeeesseeecsesaececseeeeeesaeeecsesaeeeesseeeenses 7 4 7274 LUENING OM LTONSPOPL 2 7 4 7 7 2 Assigning the Parameters to the 7 5 7 8 ASSIGNING THE R
19. 0 005 10 1 1986 12 00 00 0 005 10 1 1986 12 00 00 0 001 12 1 1986 12 00 00 0 001 11 Select the OK button twice to exit both dialogs Instead of repeating this same procedure for the other recharge zones we will import previously generated time series curves These curves were generated using this same editor and saved to text files using the Export button 1 Select the two polygons that make up recharge zone 3 in Figure 11 1 Click on the first polygon and then hold down the Shift key while clicking on the second polygon Select Properties button eS In the Recharge Rate column for the first polygon select the down arrow 21 button and select the lt transient gt option from the drop down list Now click the J button for the Recharge rate to bring up the XY Series Editor Select the Jmport button on the right side of the dialog Managing Transient Data 11 5 6 Select the file named zone3 xys 7 Select the Open button A time series curve should appear in the dialog Click OK 8 Repeat steps 3 7 for the other polygon 9 Select the OK button 10 Repeat the same procedure with recharge zone 4 except import the file named zone4 xys 11 6 2 Importing Pumping Well Data In addition to the transient recharge data our simulation will also contain a transient pumping schedule for the three wells in the model Since our model only has three wells the transient pumping schedules could easily
20. 1 Select the OK button to exit the dialog 2 Click outside the arc group to unselect it 3 Select the Save button 4 Switch to the 3D Grid module 8 5 Select MODFLOW Run MODFLOW command 6 When the model finishes running select the C ose button At this point you should see a calibration target appear for the observed flow on the arc group 8 9 Generating Error Plots Next we will generate some plots related to the calibration error We will create two plots related to error at the observation points Model Calibration 8 9 1 Select the Plot Wizard button 2 Select the Computed vs Observed Data plot 3 Select the Next button 4 Select the Finish button In the first plot a symbol is drawn for each of the observation points A point that plots on or near the diagonal line indicates a low error Points far from the diagonal have a larger error 8 10 Editing the Hydraulic Conductivity The next step in the calibration exercise is to change the model parameters and re run the model Note if you switch to the observation coverage that the errors on the left and right side of the model are mostly red and negative This indicates that the observed value is much larger than the current computed value We will begin by changing the hydraulic conductivity in these zones The hydraulic conductivity will be edited by changing the hydraulic conductivity assigned to the polygonal zones in the conceptual mode
21. 3 Select the New button This adds a new instance of a drain to each of the selected cells At this point we must enter an elevation and a conductance for the selected drains The drains all have the same conductance but the elevations are not all the same 1 Enter the following values for the elevations and conductances of the drains MODFLOW Grid Approach 2 11 2 Select the OK button 3 Unselect the cells by clicking anywhere outside the grid 2 11 The Well Package Next we will define several wells by selecting the cells where the wells are located and using the Point Sources Sinks command 2 11 1 Top Layer Wells Most of the wells are in the top layer but some are in the middle and bottom layers We will define the wells in the top layers first 1 While holding down the Shift key select the cells shown in Figure 2 3 L Constant Head Select these cells 9 9 9 9 9 9 9 9 9 9 9 9 ojo Figure 2 3 Cells to be Selected on Layer 2 Select the MODFLOW Sources Sinks command 3 Select the Well tab 2 17 GMS Tutorials Volume 4 Select the New button 5 Enter a Flow value of 432 000 for all the wells a negative value signifies extraction 6 Select the OK button 7 Unselect the cells by clicking anywhere outside the grid 2 11 2 Mid
22. This concludes the MT3DMS Conceptual Model Approach tutorial Here the things that you should have learned in this tutorial e If you are starting with a MODFLOW conceptual model you must turn on transport in the conceptual model properties e You can use MT3D Run Options command to tell MT3D what MODFLOW solution you want to use 8 Model Calibration An important part of any groundwater modeling exercise is the model calibration process In order for a groundwater model to be used in any type of predictive role it must be demonstrated that the model can successfully simulate observed aquifer behavior Calibration is a process wherein certain parameters of the model such as recharge and hydraulic conductivity are altered in a systematic fashion and the model is repeatedly run until the computed solution matches field observed values within an acceptable level of accuracy GMS contains a suite of tools to assist in the model calibration process These tools are described in this tutorial The model calibration exercise in this tutorial is based on the MODFLOW model Thus you may wish to complete the MODFLOW Conceptual Model Approach tutorial prior to beginning this tutorial Although this particular exercise is based on MODFLOW the calibration tools in GMS are designed in a general purpose fashion and can be used with any model 8 1 Description of Problem A groundwater model for a medium sized b
23. 3 Select the file entitled tex gpr 4 Select the Open button You should see a MODFLOW model with a solution and a set of GIS coverages The four coverages include a source sink a recharge and two layer attribute coverages 12 6 Model Parameterization The first steps in setting up a stochastic model are similar to those used to start an inverse model you need to parameterize the input This involves identifying which parts of the model input we wish to randomize The parameters with the highest uncertainty are obvious candidates for parameterization When parameterizing a model care should be taken to keep the number of selected parameters small If too many parameters are chosen unreasonably large numbers of model runs must be completed in order to adequately explore a sufficient combination of parameters For this model we will only use three parameters to ensure that the model run times will be fifteen minutes or less depending on the speed of your computer 12 7 Defining the Parameter Zones The conceptual model approach used in GMS allows us to quickly define our parameter zones because the conceptual model consists of zones of recharge Stochastic Modeling Parameter Randomization 12 5 and hydraulic conductivity defined by polygons We will mark the polygons as parameter zones by assigning a key value to each polygon The key value should be a value that is not expected to occur normally in the MODFLOW
24. 8 4 8 6 1 Creating a Coverage With Observation 8 4 8 6 2 Creating an Observation 8 5 8 6 3 8 5 9 06 12 Point 8 6 8 7 READING IN A SET OF OBSERVATION 8 0 8 7 8 7 11 Deleting the Current Coverage 8 7 622 8 7 8 8 ENTERING THE OBSERVED STREAM 4 42 02222 240 000 100000000000000000005000 8 7 8 9 GENERATING 222 8 8 8 10 EDITING THE HYDRAULIC CONDUCTIVITY 2 2 000000000000000005000000000000000000000000000 8 9 8 11 CONVERTING THE MODEL ccccccecssscecesssececssscececsnceeeseaeeecseseeeecseeeeessaeeecsesseeeceeeeeesesaeeessesaeeecneaaeens 8 10 8 12 COMPUTING AS OLUTION isa hi deduces duck sven 8 10 Table of Contents ix 8 12 1 Saving he StMUlation secession 8 10 8 12 2 Riunnine MO DEL OW Bee
25. Automated Parameter Estimation 9 15 7 Switch back to the 3D Grid module 8 Right click the pest solution in the Data Tree and select the Properties command This command brings up a spreadsheet showing the error from this model run The spreadsheet shows the error from the head observations the flow observations and the combined weighted observations Note that these values are significantly lower than the values we obtained with the MODFLOW 2000 PES process 9 20 Viewing the Final Hydraulic Conductivity When PEST ran a new conductivity value was estimated at each of the scatter points used with the HK_100 parameter Now we will read in the optimal parameter values as determined by PEST Reading in the optimal parameter values will create a new data set for our scatter point set Then we can interpolate from the scatter point set to the grid to see our final hydraulic conductivity field 1 Select the VODFLOW Parameters command 2 Click the Import Optimal Values button 3 Select the pest par file and select the Open button Notice that the starting values for the parameters have changed 4 Select the Options button in the Pilot Point Options column for the HK_100 parameter Notice that the data set has been changed to HK_100 PEST 5 Select OK twice to exit the both dialogs 6 Switch to the 2D Scatter Point module 7 Double click the HK scatter point set in the Data Tree You should see 2 data sets
26. Building the POL CONS 4 13 494 Assigning the Recharge 4 13 4 10 DEFINING THE HYDRAULIC 2 2 1 2 2 2 0000 000055050 4 14 4 10 1 Copying the a e ia A aa A E E 4 14 4 10 2 LODE OCT O E AAEE E E RT 4 15 4 10 3 e e Sh pag BaP Ss Ses 4 15 4 11 CEOCATING THE GRID FRAME 4 15 4312 CREATING THE GRID 4 16 4 13 DEFINING THE ACTIVE INACTIVE ZONES ccccccessscessceessecessceesseceseeeessecesseeesaeceseeeeseecsseeeeseeceseeeeseeces 4 16 4 14 INITIALIZING THE MODFLOW 2 4020000 4 17 4 15 LAYER ELEVATIONS 2412 4 404442000000 000000000000 4 17 4 15 1 Importing the Ground Surface Scatter 4 17 Table of Contents vii 4 15 2 Interpolating the Heads 4 18 4 15 3 Interpolating the Layer 4 18 4 15 4 Adjusting the nce 4 18 4 15 5 Viewing the Model Cross 4 19 4 15 6 Fixing the Ele
27. You can also display the contours using a color fill option 1 Select the Data Contour Options command in 2 Change the Contour Method to Color Fill 3 Select the OK button 2 15 3 Color Legend Next we will display a color legend 1 Select the Data Color Ramp Options command 2 Turn on the Legend option 3 Select the OK button 2 16 GMS Tutorials Volume 2 16 Conclusion This concludes the MODFLOW Grid Approach tutorial Here are the things that you should have learned in this tutorial You can specify which units you are using and GMS will display the units next to input fields to help you input the appropriate value GMS does not do any unit conversions for you The MODFLOW menu is in the 3D Grid module The MODFLOW packages you want to use in your model can be selected by choosing the MODFLOW Global Options command and clicking the Packages button Most MODFLOW array data can be edited in two ways via a spreadsheet or by selecting grid cells and using the MODFLOW Cell Properties command Wells Drains etc can be created and edited by selecting the grid cell s and choosing the MODFLOW Sources Sinks command You can use the Model Checker to analyze the input data and check for errors In Ortho mode only one row or column or layer of the 3D grid is visible at a time CHAPTER 3 MODAEM MODAEM is a single layer steady state analytic element groundwater flow model that has been e
28. If you expand the folder containing the mfpes solution you should see a text file in the Data Tree named mfpes glo If you double click on this file it will open in a text editor This file shows the model inputs as well as information concerning each parameter estimation iteration 9 13 Loading Optimal Parameter Values When you are finished using the inverse model it is often desirable to load and view the optimal parameter values We will now load the optimal parameters 1 Select the VODFLOW Parameters command 2 Select the Import Optimal Values button 3 Select the mfpes _pa file and select the Open button Notice that the starting value for all of the parameters has now been changed to the optimal value computed by the inverse model Since we are now going to use PEST as our inverse model we want the starting values to be the same as we used with the MODFLOW PES process We will cancel out of this dialog and restore the old starting values 4 Select the Cancel button to exit the dialog 9 14 PEST Now we will use PEST as our inverse model to solve the same problem However we will use a different method for parameterization While it certainly is possible to use the zonal method of parameterization with PEST we would get an answer very similar to the answer the MODFLOW 2000 PES process gave us However for this problem we will use the zonal approach for recharge but we will use the pilot point interpolation method for hydraul
29. that the head is continuous across the boundary In these cases it is almost always necessary for the modeler to provide an initial guess for the average MODAEM 3 5 head in the sub domain GMS provides an option see below for specifying this property Tips tricks and suggestions This section provides a few tips that will help the new AEM modeler It is important to keep these points in mind when building your first MODAEM model Line sinks and resolution issues In there are several applications of line sink elements e Constant discharge line sinks e Constant head line sinks Rivers analogous tt MODFLOW RIV Drains analogous to MODFLOW DRN e General head boundaries analogous to MODFLOW GHB In MODAEM each line sink is a line segment along a path digitized by the user Each segment has a sink density which is the amount of water added to the aquifer or removed from the aquifer per unit length of the line segment For constant discharge line sinks GMS allows the modeler to enter either the total amount of water added to the aquifer for a string of line sinks or the sink density to be applied to each line sink A common misconception for new AEM modelers arises with constant head line sinks The term constant head does not mean that the head is actually the same everywhere along the element but that MODAEM will compute a sink density for the line sink such that the specified head is matched ex
30. with the random numbers from the other parameters such that all possible combinations of segments are sampled The total number of model runs is the product of the number of segments for each parameter For example if you have three parameters with four segments each and one with five the total number of simulations would be 4 x 4 x 4 x 5 320 In GMS the total area under the probability curve is further limited by the specified maximum and minimum to give the maximum parameter range while still maintaining the best chance for model stability The greater certainty from a smaller number of runs comes from guaranteeing that a more complete set of parameter combinations is tested We will be using the Latin Hypercube approach in this tutorial 12 3 Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state 12 4 GMS Tutorials Volume 12 4 Required Modules Interfaces You will need the following components enabled to complete this tutorial Grid Map MODFLOW Stochastic Modeling You can see if these components are enabled by selecting the File Register command 12 5 Reading in the Project First we will read in a modeling project representing a completed MODFLOW model for the East Texas site 1 Select the Open button gt 2 Locate and open the tutfiles stochastic1 directory
31. 4 SAVING THE PROJECT AND RUNNING MODFLOW 13 5 READING IN AND VIEWING THE MODFLOW SOLUTIONS 13 5 DISPLAYING PATHLINES wane ee Reon 13 5 PROBABILISTIC CAPTURE ZONE ANALYSIS 13 6 CONCLUSION 13 7 1 Introduction This document contains tutorials for the Department of Defense Groundwater Modeling System GMS Each tutorial provides training on a specific component of GMS Since the GMS interface contains a large number of options and commands you are strongly encouraged to complete the tutorials before attempting to use GMS on a routine basis The tutorials are not intended to teach groundwater modeling concepts They are only meant to illustrate the use of GMS In addition to this document the online GMS Help document also describes the GMS interface Typically the most effective approach to learning GMS is to complete the tutorials before browsing the GMS Help document 1 1 Suggested Order Of Completion In most cases the tutorials can be completed in any desired order However some of the tutorials are pre requisites for other tutorials Tutorials that have other tutorials as pre requisites will indicate it at the beginning of the tutorial 1 2 Demo vs Normal Mode The interfa
32. 6 GMS Tutorials Volume updated Notice how dramatically the capture zone changes from one solution to the next 13 10 Probabilistic Capture Zone Analysis Now that we have a MODFLOW stochastic solution set we can perform a probabilistic capture zone analysis for the wells in our model A probabilistic capture zone analysis is performed by placing one or more particles in each cell and tracking the particles forward in time using MODPATH to see if they reach a well If any of the particles from a cell reach the well a counter for the cell is updated After running MODPATH on each of the MODFLOW solutions the percentage of particles from a particular cell that are eventually captured by the well is computed and saved as the capture probability for the cell The capture probability data set can then be contoured 1 Select the MODFLOW solution set matsto MODFLOW STO from the Data Tree window 2 While the MODFLOW solution set is selected in the window right click on the solution set and choose Risk Analysis This brings up the Risk Analysis Wizard 3 that MODFLOW 15 selected in the list box and select the Probabilistic capture zone analysis option 4 Select the Next button You should now see the next page in the Risk Analysis Wizard We can use this page to specify options for the position and number of particles for each cell In the Particle starting locations area we can choose to place particles on th
33. 9 GMS Tutorials Volume Creating the Specified Head Arcs By default the arcs in a MODAEM boundary coverage are no flow boundaries This means the arcs type is set to specified flow and the flow is set to 0 Next we will add specified head arcs to this coverage To create the specified head arcs we will split the boundary arc into four separate arcs 1 Select the Select Vertices tool 2 Select the four vertices displayed in the figure below To select more than one vertex you must hold the shift key while selecting You may need to insert additional vertices This can be done by using the Create Vertex tool 2 Simply select the tool and then click on the arc in the location that you want the new vertex to be Also depending on how you created your boundary arc one of the vertices shown in the figure above may actually be a node In that case you will not be able to select it with the select vertex tool If you do have a node at one of the locations shown above just select the other three vertices 3 Once you have the vertices selected select the Feature Objects Vertices lt gt Nodes command 3 13 Select the Select Arcs tool Select the two new arcs that we created the north and south of the boundary Figure 3 9 Specified Head Arcs 6 7 10 11 12 Select Properties button ES In the All row change the type to spec head Select
34. Control By default MT3DMS outputs a solution at every transport step Since this results in a rather large output file we will change the output so that a solution is written every time step every 300 days 1 Select the Output Control button 2 Select the Print or save at specified times option 3 Select the Times button 4 Select the Initialize Values button 7 4 GMS Tutorials Volume oy Enter the following values Initial time step size 300 Bias 1 Maximum time step size 300 Maximum simulation time 3000 Select the OK or Close buttons three times to return to the Basic Transport Package dialog 7 6 4 Selecting the Packages Next we will specify which of the MT3DMS packages we intend to use 1 4 Select the Packages button Turn on the following packages Advection package Dispersion package Source Sink Mixing package GCG package options Select the OK button Note that the Basic Transport Package dialog also includes some layer data We will address the data for these arrays at a latter point in the tutorial Select the OK button to exit the Basic Transport Package dialog 7 7 Assigning the Aquifer Properties 7 7 1 1 2 MT3DMS requires that a porosity and dispersion coefficient be defined for each of the cells in the grid While these values can be assigned directly to the cells it is sometimes convenient to assign the parameters using polygonal zones defined in
35. Entering Transient Data in the Map Module The first step in setting up our transient model is to associate our transient data with the feature objects in the Map Module 11 6 1 Assigning the Transient Recharge Rate First we will assign the transient recharge rate for the recharge zones The recharge zones are shown in Figure 11 1 There are four recharge zones defined by five polygons We will leave the recharge rate for zone 1 at zero We will assign a transient recharge rate to the other three zones Recharge Zones Figure 11 1 Recharge Zones To assign the recharge data 1 Switch to the Map module 11 4 GMS Tutorials Volume 9 Expand the Conceptual Model item in the Data Tree Select the Recharge coverage to make it active Choose the Select Polygon tool Select the polygon corresponding to recharge zone 2 in Figure 11 1 Select Properties button ES For the Recharge rate click the down arrow button and select the lt transient gt option from the drop down list Now click the J button for the Recharge rate to bring up the XY Series Editor Select the Use dates times toggle 10 Enter the following date times and recharge rates Date Time Recharge Rate ft day 10 1 1985 12 00 00 AM 0 001 1 1 1986 12 00 00 AM 0 001 1 1 1986 12 00 00 0 0005 3 1 1986 12 00 00 0 0005 3 1 1986 12 00 00 0 006 7 1 1986 12 00 00 0 006 7 1 1986 12 00 00
36. MODAEM and MODFLOW models in general data will only need to be entered once for projects that use both codes This has these important implications 1 Flow rates for wells and discharge specified line sinks follow the MODFLOW convention which is that a pumping well has a negative discharge rate and an injection well has a positive discharge rate 2 The resistance for rivers drains and GHBs has been replaced with a conductance in a manner consistent with MODFLOW For a river the conductance is defined as 12 in units of 11 where Cis the conductance Wis the stream width kis the vertical hydraulic conductivity of the stream bed and fcis the thickness of the stream bed 3 Aquifers can be bounded just as in MODFLOW The boundary is constructed of left discharge line sink elements and continuity of flow is guaranteed within the closed domain Currently GMS supports discharge specified and head specified boundaries MODAEM also supports general head boundaries these may be included in a future GMS release Experienced AEM users may wish to review the remainder of this section however if you are familiar with the proper use of AEM codes you may skip to the next section What are analytic elements The AEM is based on the use of analytic solutions for problems in groundwater flow For example the potentiometric heads due to a well in two dimensions is shown in Figure 3 1 a below Most
37. MODFLOW layer data to a 2D scatter point set 1 Switch to the 3D Grid module 2 Select the Grid MODFLOW Layers gt 2D Scatter Points command 3 Change the scatter point set name to Regional Data 4 Select the OK button You should see a set of scatter points appear at the location of the cell centroids This scatter point set has a data set for the computed heads and for the top and bottom elevations of the model layers 10 6 Approach to Building the Local Model Next we will build the local model There are numerous approaches to building the local model A common approach is to mark the boundaries of the local model as specified head boundaries using the computed head values from the regional model The following method accomplishes this objective A rectangular grid is constructed where two opposite boundaries are parallel to head contours from the regional model 1 a constant head value along each boundary The other two boundaries are no flow boundaries and are perpendicular to the head contours from the regional model 10 7 Building the Local Conceptual Model The simplest way to build the local model is to create a conceptual model in the Map module To do this we will create a new conceptual model 1 Switch to the Map module 2 Right click on the Regional Model item and select the Duplicate command 3 Change the name to Local Model 10 7 1 Creating a New Coverage Next we will create a new source
38. Model Approach 4 17 specified head boundaries approximately coincide with the cell centers of the cells on the perimeter 4 14 Initializing the MODFLOW Data Now that the grid is constructed and the active inactive zones are delineated the next step is to convert the conceptual model to a grid based numerical model Before doing this however we must first initialize the MODFLOW data 1 Switch to the 3D Grid module 2 Select the VODFLOW New Simulation command 3 Select the OK button 4 15 Interpolating Layer Elevations The final step before we save the model and run MODFLOW is to define the layer elevations and the starting head Since we are using the LPF package top and bottom elevations are defined for each layer regardless of the layer type For a two layer model we need to define a layer elevation array for the top of layer one the ground surface the bottom of layer one and the bottom of layer two It is assumed that the top of layer two is equal to the bottom of layer one The simplest way to define layer elevations is to import a set of scatter points defining the elevations and interpolate the elevations directly to the layer arrays In some cases this is done using one set of scatter points In this case we will use two scatter point sets one for the ground surface and one for the elevations of the bottom of layer one and the bottom of layer two It is often convenient to use two scatter point sets in this fashi
39. Vertices are used solely to define the geometry of the arc Polygons are a group of connected arcs that form a closed loop A polygon can consist of a single arc or multiple arcs If two polygons are adjacent the arc s forming the boundary between the polygons is shared not duplicated Feature objects are grouped into coverages Each coverage represents a particular set of data MODAEM 3 9 Point O Node Vertex Arc Polygons Figure 3 5 Feature Objects 3 6 Reading in the Background Map The first step to create our model is to read in a background image of the site we are modeling We will use the image to guide us as we create points arcs and polygons to define features of our model 1 Select the Open button gt 2 Locate and open the directory entitled tutfiles modaem 3 Select and open the file indiana tiff At this point the image registration dialog appears If the image file had an associated world file or if the file contained a geo reference then the registration dialog would not appear This image file does not have any geo referencing information so we will have to provide this information by identifying the real world coordinates at different points on the image 4 In the Register Image dialog select the Two Point Registration option 5 Position the red crosshairs as shown in the image below and enter the coordinates 6 Select OK to exit the dialog 3 10 GMS Tutorials Volume
40. a coverage of recharge zones and a coverage of hydraulic conductivity zones For the initial simulation a single value of hydraulic conductivity 8 ft day and a single value of recharge 2 5e 4 ft day have been assigned The polygonal zones of hydraulic conductivity and recharge will be edited as the tutorial progresses to reduce the model error The conceptual model was used to construct the MODFLOW model that is shown 8 5 Observation Data We will be using two types of observation data in the calibration process water table elevations from observation wells and observed flow rates in the stream Since the model is in a fairly arid region we will assume that most of the flow to the stream is from groundwater flow 8 6 Entering Observation Points 8 6 1 First we will enter a set of observation points representing the observed head in the ten observation wells in the region Observation points are created in the Map module Creating a Coverage With Observation Properties Before entering observation points we must first create a coverage with observation properties 1 Switch to the Map module 2 In the Data Tree right click the BigVal conceptual model select the New Coverage command from the pop up menu 3 Name the new coverage Observation Wells 4 In the list of Observation Points properties turn on Head 5 Change the 3D grid layer option for obs pts option to By layer number 6 Select the OK
41. accurate solution it is important to ensure that each segment of a line sink string lies entirely within a single sub domain A correct arrangement is shown below The inhomogeneity has a hydraulic conductivity 100 times larger than the outside conductivity and the boundary of the inhomogeneity crosses the line sink string at a vertex Description of Problem This tutorial describes the use of GMS to model groundwater flow near the well field of Brazil IN Brazil population 8188 operates a well field about 5 MODAEM 3 7 miles east of town in the floodplain of Big Walnut Creek see Figure 1 The objectives of this model are to 1 Model the 5 year capture zone for the wellfield for use in the Brazil wellhead protection effort 2 Examine the effects of the addition of an additional well to the wellfield The following figure shows the site location along with the model boundaries 7 5 2 4 AN Figure 3 4 Model Boundary 3 2 1 Setting and Data Collection The wellfield is situated in the floodplain of Big Walnut Creek The aquifer is composed of coarse gravel with an average hydraulic conductivity of 250 ft d 60 9 m d deposited in a buried bedrock valley Although the bedrock surrounding the valley is slightly permeable it is not considered an important source of water The thickness of the gravel aquifer in the valley varies from 10 80 ft 3 0 24 4 At the wellfield the gro
42. below the scatter point set Make sure that the HK_100 PEST data set is active In order to view the hydraulic conductivity field we need to make sure that the interpolation scheme is the same as the interpolation scheme used for the pilot points 1 Select the Interpolation Interpolation Options command and make sure that the selected interpolation scheme is Inverse distance weighted 9 16 GMS Tutorials Volume 9 Select the Options button next to the Inverse distance weighted option Make sure that the nodal function is Constant Select OK twice to exit both dialogs Select the Interpolation Interpolate gt 3D Grid command Select OK to accept the default data set name and perform the interpolation Switch to the 3D Grid module Select the Display Display Options command Turn off the Contours option and turn on the Cell faces option Make sure the Data colors option is selected below the Cell faces option Select the Options button below the Cell faces option 10 In the bottom left portion of the dialog turn on the Show legend option 11 Select OK twice to exit both dialogs You should now see the final hydraulic conductivity values for you MODFLOW simulation 9 21 Conclusion This concludes the Automated Parameter Estimation tutorial are the things that you should have learned in this tutorial You can use the zonal approach or the pilot point approach with both PEST and the MF2K
43. button to exit the Observation Coverage dialog Model Calibration 8 5 8 6 2 Creating an Observation Point We are now ready to create an observation point The first point we will be creating has the following values ft Head ft Interval ft Confidence 14661 32694 999 0 The interval represents the estimated error the observed value The confidence value represents the confidence in the error estimate The interval can be used as a calibration target Calibration is achieved when the error is within the estimated error interval 1 5 ft in this case of the observed value In other words if the computed head falls between 997 5 1000 5 the calibration target is reached for this observation well To create the point 1 Select the Create Point tool 2 Click once anywhere on the model 3 With the point selected change the X and Y values in the Edit Window to X 14661 Y 32694 To assign the properties to the point 1 With the point still selected select the Properties button 2 Change the name of the point to Point 1 3 Change the to obs pt 4 Enter 999 for the Obs Head 5 Enter 1 5 for the Obs Head Interval 6 Enter 95 for the Obs Head conf 7 Select the OK button 8 6 3 Calibration Target At this point a calibration target like the one shown in Figure 8 3 typically shows up next to the observation point In this case however the observation measur
44. can be automatically generated by GMS using the Jnitialize From Model button When this button is selected GMS searches the MODFLOW input data for likely key values and creates a list of parameters If a parameter is not automatically found by GMS it can be added using the New Parameter button 2 Select the Initialize from Model button Note that all seven parameters were automatically found Also note that the parameters have been given a default name The next step is to enter a starting minimum and maximum value for each parameter Special care should be taken when selecting the starting values In most cases using arbitrary starting Automated Parameter Estimation 9 7 values will cause the inverse model to fail to converge The closer the starting values are to the final parameter values the greater the chance that the inverse model will converge The starting values we will use were found after a few iterations of manual trial and error calibration 3 Enter the following data into the parameters spreadsheet Name Start Value Min Value Max Value 100 4 0 01 100 200 8 0 01 100 300 2 0 01 100 400 0 5 0 01 100 500 0 00035 1 10 0 0005 600 0 00025 1 10 0 0005 700 0 00020 1 10 0 0005 For each of the hydraulic conductivity parameters turn on the Log transform option Select OK to exit the dialog 9 10 Max Iterations Finally we
45. cells you currently have particles in You may wish to view this solution in cross section view as well 6 Click anywhere outside the grid to unselect the cells 5 10 Color by Zone Code Some of the pathlines that start at the landfill should terminate at the well We want to easily identify these so we will make them a different color First we ll turn off the display of the particles coming from the well 1 Inthe Data Tree turn off the display of the 1 000 days and 3 000 days particle sets by unchecking them Now we ll change the zone code for the cell containing the well 2 Select the Decrement button in the Mini Grid Plot to view layer 2 of the grid 3 With the Select Cells tool Ae select the cell with the well in it You may need to zoom in to do this 4 Select the Cell Properties command 5 8 GMS Tutorials Volume 5 Change the Zone code to 2 and click OK 6 Select the MODPATH Display Options command 7 Inthe Color pull down list change the selection to Ending code 8 Select the OK button The pathlines that go from the landfill to the well should now be drawn in a different color 5 11 Pathline Length Time One reason to do particle tracking is to find out how long it will take for particles to travel from one place to another In this case we want to know how long it will take for particles to travel from the landfill to the well GMS reports the length and travel time of
46. discharge potential the head is the hydraulic conductivity and His the aquifer height For the case where the flow condition is just confined and the two potential expressions are numerically equal This allows MODAEM to simulate confined and unconfined flow in a regional model The model is solved in terms of the potential and either the confined or the unconfined expression is used to compute the head depending on whether the potential is larger or smaller than the potential at the aquifer top For the modeler this is the most important reason to understand that MODAEM uses discharge potentials When you create an aquifer in MODAEM the flow is confined whenever the head exceeds the aquifer top automatically To make a model where the flow is unconfined everywhere specify an aquifer thickness such that the aquifer top is above the head everywhere in the model or a sub domain Obviously the ability to model confined and unconfined flow in the same model is one advantage but discharge potentials also facilitate inhomogeneities contrasts in aquifer properties The discharge potential makes it possible to write an expression for the jump in the potential along the boundary of sub domains fortunately the mathematics are omitted here However this formulation is non linear when the flow is unconfined on one or both sides of the sub domain boundary the model must do several iterations to ensure
47. for the Time interval 6 Select the Finish button You should see some images appear on the screen These are the frames of the animation which are being generated 1 After viewing the animation select the Stop button to stop the animation 2 Select the Step button to move the animation one frame at a time 7 10 GMS Tutorials Volume 3 You may wish to experiment with some of the other playback controls When you are finished close the window and return to GMS 7 19 Modeling Sorption and Decay The solution we have just computed can be thought of as a worst case scenario since we have neglected sorption and decay Sorption will retard the movement of the plume and decay due to biodegradation will reduce the concentration For the second part of the tutorial we will modify the model so that sorption and decay are simulated We will then compare this solution with the first solution 7 19 1 Turning on the Chemical Reactions Package Sorption and decay are simulated in the Chemical Reactions Package We need to turn this package on before it can be used 1 2 Select MT3D Basic Transport Package command Select the Packages command Turn on the Chemical reaction package option Select the OK button to exit the Packages dialog Select the OK button to exit the Basic Transport Package dialog 7 19 2 Entering the Sorption and Biodegradation Data Next we will enter the sorption and biodegradatio
48. in Parameter Estimation mode The error and parameter values are shown in the spreadsheet in the upper right side of the dialog and the plot on the left shows the error In this case you may notice some strange parameter names like These names were automatically generated and assigned to the scatter points PEST will take several minutes to run You should see the residual error go to an extremely small value When PEST is finished you will see a message in the text portion of the window the Abort button will change to Close 9 19 Viewing the Solution Once PEST is finished you can read in the solution 1 Select the Close button Make sure that the Read solution on exit toggle is checked The contours currently shown on the 3D grid are the heads from the MODFLOW with the optimum parameter values We will now look at the observation targets in the map model and the error associated with this model run N 2 Switch to the Map module 3 Select the Sources amp Sinks coverage from the Data Tree Notice that the observation target on the arc group almost exactly matches 4 Select the Select Arc Group tool 5 Select the arc group by clicking on the river arc Notice in the edit strip at the bottom of the graphics window the computed and observed flow is reported 6 Select the Observation Wells coverage from the Data Tree Notice that there is no visible error at any of the observation points
49. input A negative value typically works well 12 7 1 Setting up the Recharge Zones First we will set up the recharge zones The recharge polygons are shown in Figure 12 2 We will define a parameter for both the small polygon defining the landfill and the larger polygon encompassing the rest of the site The key values associated with the two zones are shown on the polygons in the figure The 200 zone represents recharge to the aquifer from rainfall The 100 zone represents leakage from the landfill to the aquifer Figure 12 2 Recharge Zones Representing Aquifer Recharge 200 Landfill Leakage 100 To assign the key values to the polygons 1 2 If necessary switch to the Map module Expand the East Texas conceptual model by clicking the plus symbol next to it in the Data Tree Switch to the Recharge coverage by selecting it from the Data Tree Select the Select Polygon tool Double click on each of polygons show in Figure 12 2 and assign the appropriate key value to the Recharge Rate input field 12 6 GMS Tutorials Volume 12 7 2 Setting up the Hydraulic Conductivity Zone Next we will parameterize the hydraulic conductivity for the top layer For simplicity we will assume that the hydraulic conductivity is constant for the entire layer 1 Switch to the Layer 1 coverage by selecting it from the Data Tree 2 Double click on the polygon and assign a key value of 300 to the H
50. model to unselect the cells 4 23 Conclusion This concludes the MODFLOW Conceptual Model Approach tutorial Here are the things that you should have learned in this tutorial A background image can be imported to help you construct the conceptual model It is usually a good idea to define the model boundary in a coverage and copy that coverage whenever you need to create a new coveage You can customize the set of properties associated with points arcs and polygons by using the Coverage Setup dialog Some arc properties like head are not specified by selecting the arc but by selecting the nodes at the ends of the arc That way the property can vary linearly along the length of the arc A grid frame can be used to position the grid but is not required You must use the Map gt MODFLOW MODPATH command every time you want to transfer the conceptual model data to the grid You can specify things like layer elevations and hydraulic conductivities using polygons in the conceptual model but that will result in stair step like changes For smoother transitions you can use 2D scatter points and interpolation CHAPTER 5 MODPATH This tutorial describes the steps involved in setting up a MODPATH simulation in GMS MODPATH is a particle tracking code developed by the U S Geological Survey MODPATH tracks the trajectory of a set of particles from user defined starting locations using the MODFLOW solution as the flow field The
51. particles can be tracked either forward or backward in time Particle tracking solutions have a variety of applications including the determination of zones of influence for injection and extraction wells 5 1 Description of Problem The problem we will be solving for this tutorial is an extension of the problem described in the previous tutorial entitled MODFLOW Conceptual Model Approach If you have not yet completed the previous tutorial you may wish to do so before continuing In the previous tutorial a site in East Texas was modeled We will be using the solution from this model as our flow field for the particle tracking simulation The model includes a proposed landfill For this tutorial we will be performing two particle tracking simulations to analyze the long term effects of contamination from the landfill First we will do reverse particle tracking from the well on the east side of the model to see if the zone of influence of the well overlaps the landfill Then we will do forward tracking using an array of particles starting at the landfill to analyze the region of potential contamination for the landfill 5 2 GMS Tutorials Volume 5 2 Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state 5 5 Required Modules Interfaces You will need the following components ena
52. representation of the grid should also appear in the Mini Grid Plot in the Tool Palette 2 6 Creating the MODFLOW Simulation The next step in setting up the model is to initialize the MODFLOW simulation 2 4 GMS Tutorials Volume 1 Select the New Simulation command 2 6 1 Global Package The input to MODFLOW is subdivided into packages Some of the packages are optional and some are required One of the required packages is the Global package We will begin with this package Packages First we will select the packages 1 Select the Packages button The packages dialog is used to specify which of the packages we will be using to set up the model The Basic package is always used and therefore it cannot be turned off To select the other packages 2 Select the Drain Well and Recharge packages 3 In the Solver section select the Strongly Implicit Procedure package 4 Select the OK button to exit the Packages dialog The IBOUND Array The next step is to set up the IBOUND array The IBOUND array is used to designate each cell as either active IBOUND gt 0 inactive IBOUND 0 or constant head IBOUND lt 0 For our problem all cells will be active except for the first two layers in the leftmost column which will be designated as constant head 5 Select the BOUND button The JBOUND dialog displays the values of the IBOUND array in a spreadsheet like fashion one layer at a time
53. row Type column select the drain option 5 Enter a conductance of 6000 for all three arcs This represents a conductance per unit length value GMS automatically computes the appropriate cell conductance value when the drains are assigned to the grid cells 6 Change the From layer and To layer properties to be 1 for each of the arcs This means the drains will only be in layer 1 of the grid 7 Select the OK button The elevations of the drains are specified at the nodes of the arcs The elevation is assumed to vary linearly along the arcs between the specified values 4 10 GMS Tutorials Volume 4 8 3 1 Select the Select Points Nodes tool 2 Double click on Node 2 in Figure 4 5 Notice that this node has 2 properties associated with it since it is attached to 2 arcs of different types 3 Enter 696 for the Bot elev of the drain property Do NOT change anything in the spec head property Click OK 4 Repeat this procedure to assign the drain elevations to the nodes shown in Figure 4 5 Be sure to change the drain property only and NOT the spec head property GG ny 4 27 Node5 oy Elevation gt 730 26 696 67 727 692 5 Z 730 4 Figure 4 5 Elevations for Drain Nodes Building the polygons With the local sources sinks type coverage the entire region to be modeled must be covered with non overlapping polygons Thi
54. shown in Figure 8 2 The five polygons will be used to define four parameter zones The polygon at the top end of the model is relatively small it is isolated from the majority of the observation wells and it is downgradient from the wells As a result it is not a good candidate for parameter estimation We will fix the recharge in this zone at zero The key values will be associated with the other four polygons to define three parameter zones as shown Automated Parameter Estimation 9 5 Recharge Zones Be 500 ia Figure 9 2 Recharge Zones and Parameter Key Values To assign the key values to the polygons 1 Switch to the Recharge coverage by selecting it from the Data Tree 2 Double click on each of the polygons shown in Figure 8 2 and assign the appropriate key value to the Recharge rate input field 9 6 3 Mapping the Key Values to the Grid Cells Once the key values are assigned to the polygons they must be mapped to the cells in the MODFLOW grid 1 Select the Feature Objects Map gt MODFLOW MODPATH command 2 Select OK at the prompt 97 Selecting the Parameter Estimation Option Before we edit the parameter data we will turn on the Parameter Estimation option This option is turned on in the Global Options dialog 1 Switch to the 3D Grid module amp 2 Select the MVODFLOW Global Options command 3 In the Run Options section of the dialog select the Parameter Estimation option 9 6 G
55. the Delete button 5 4 GMS Tutorials Volume 5 6 1 Viewing the Pathlines in Cross Section View The 3D nature of the pathlines is best seen in cross section view 1 Select the Select Cell tool Ae 2 Select a cell near the right landfill 3 Select the View J Axis button You may wish to move back and forth through the columns using the arrows in the Mini grid plot When finished 4 Select the View K Axis button 27 5 7 Display Options addition to displaying the pathlines GMS draw a closed boundary around the pathlines connected to the well This boundary is referred to as a capture zone Capture zones can only be displayed if you are in plan view GMS has a number of options for the display of pathlines and capture zones 1 Select the MODPATH Display Options command 2 Turn on Direction arrows 3 Make sure the Boundary option in the Capture zones section is turned on 4 Turn on the Poly fill option in the Capture zones section 5 Select the OK button You should now see arrows on the pathlines pointing in the direction of flow You should also see the capture zone filled with a solid color 5 8 Particle Sets GMS organizes starting locations into particle sets When we created the starting locations at the wells GMS automatically created a particle set and put the new starting locations in it 1 Expand the Particle Sets folder in the Data Tree 2 Right click on t
56. the Left avis eile 2 6 DAD Selecting the Cels heheh als fad Bh abet octane Ad nla 2 6 2 7 3 Changing the 2 7 244 Chechitig the Vales easel Seats Geese 2 7 2 8 2 7 2 612 Layer 2 8 28 2 LAV Cr Par metetS 552 555 3 2 8 2509 2 8 2504 oa 2 8 226 9 A N E AE O O 2 9 2 9 ein ech E Mee Seles heck E eee S 2 9 2 10 THE DRAIN PACKAGE i 2 9 2 10 1 Selecting the Cells fini es 2 9 2 10 2 Assigning the DV 2 10 221 THE WELL PACKAGE
57. the conceptual model The parameters are converted to the grid cells using the Map gt MT3DMS command Turning on Transport To assign the porosities and dispersion coefficients to the polygons Switch to the Map module In the Data Tree right click the East Texas conceptual model select the Properties command from the pop up menu MT3DMS Conceptual Model Approach 7 5 3 Tum on Transport and make sure MT3DMS is selected as the Transport model 4 Click on the Define Species button 5 Click the New button to create a new species Change the species name to leachate and click OK 6 Click OK to exit the Conceptual Model Properties dialog 7 Expand the East Texas conceptual model if necessary to see the coverages under it 8 In the Data Tree right click the Layer 1 coverage and select the Coverage Setup command from the pop up menu 9 In the list of Areal Properties turn on the following e Porosity e Long Dispersivity 10 Click OK 11 Repeat steps 7 9 for the Layer 2 coverage 7 7 2 Assigning the Parameters to the Polygons To assign the porosities and dispersion coefficients to the polygons 1 9 6 Make Layer 1 the active coverage by selecting it in the Data Tree Choose the Select Polygons tool Double click on the layer polygon For the Porosity enter a value of 0 3 For Long Disp enter a value 20 Select the OK button To assign the values to layer 2 1 2 M
58. will increase the maximum number of iterations used by the solver package This will increase the likelihood that MODFLOW will converge at each iteration 1 2 9 11 Select the MODFLOW PCG2 Package command Change the Maximum outer iterations to 100 and the Maximum inner iterations to 100 Select the OK button Saving the Project and Running MODFLOW We are now ready to save the project and run the PES process 1 2 3 4 Select the File Save As command Enter mfpes gpr for the file name Select the Save button Select the MODFLOW Run MODFLOW command MODFLOW is now running in Parameter Estimation mode The spreadsheet in the top right hand corner of the dialog shows the error and the parameter values for each iteration of the parameter estimation process The plot on the left shows the error for each iteration When MODFLOW is finished running 9 8 GMS Tutorials Volume you can view the optimum parameter values in the spreadsheet Once the PES process has found the optimum parameter values MODFLOW will run a forward run with the optimum values and output the head solution This will be the solution that we read in Note If you have room on your screen you may wish to resize the output window by dragging the handle in the lower right corner of the window 9 12 Viewing the Solution Once MODFLOW is done running you can read in the solution 1 Make sure that the Read solution on exit
59. will need the following components enabled to complete this tutorial e e Geostatistics e Map e MODFLOW You can see if these components are enabled by selecting the File Register command 10 4 Reading in the Regional Model The first step in the model conversion process is to build a regional model Since the focus of this tutorial is primarily on the conversion process we will read in a previously constructed model 1 Select the Open button gt 2 Locate and open the file entitled tutfiles reg2loc regmod gpr We are now viewing the top layer of the two layer model You may wish to use the arrow buttons in the Tool Palette to view the bottom layer The wells are located in the bottom layer When you are finished return to the top layer This model was constructed using the conceptual model approach The boundary of the local site is indicated with a red rectangle The conceptual model consists of three coverages The coverage we are viewing is for the sources and sinks There is also a coverage defining recharge zones and a coverage defining hydraulic conductivity zones for the top layer The large rectangular boundary is the grid frame The project we imported includes the solution for the regional model You should see contours of computed head 10 4 GMS Tutorials Volume 10 5 Converting the Layer Data to a Scatter Point Set The first step in converting the regional model to a local model is to convert the
60. will set up a rule to mark leachate concentrations above 10 0 GMS then searches through all the selected solutions and for each cell it counts how many times the leachate concentration is exceeded This number is then divided by the total number of solutions 27 in our case These results are then contoured as a probability threshold dataset 1 Select the MT3DMS solution set mfsto MT3DMS STO from the Data Tree window This is the folder that contains the individual MT3DMS solutions 2 While the MT3DMS solution set is selected in the window right click the solution set and choose Risk Analysis This brings up the Risk Analysis Wizard 3 Verify that MT3DMS is selected in the list box and select the Next button This next step in the Risk Analysis Wizard allows you to set up rules Because we only have one contaminant leachate we only need one rule 1 In the Value field for the first rule enter a concentration of 10 2 Change the Operator to gt 3 Change the Analysis title to 10 4 Choose the Finish button When the Risk Analysis Wizard finishes a new data set 10 will be added to the mfsto MT3DMS STO folder This data set contains the probability that the leachate concentration will be above 10 0 for each of the time steps of our MT3DMS model The best way to view this dataset is to turn on color filled contours 1 Select the Data Contour Options command 2 Change the Contour Method to C
61. you are finished close the window and return to GMS 6 6 Conclusion This concludes the MT3DMS Grid Approach tutorial Here are the things that you should have learned in this tutorial 6 8 GMS Tutorials Volume MT3Dis available if a MODFLOW model is in memory e MT3D relies on the MODFLOW solution files so if you move or rename your MODFLOW files you will probably need to regenerate the MODFLOW solution files so MT3D can find them e GMS gives MT3D the top and bottom elevation data it requires for each layer from the MODFLOW model You can use the Animation Wizard to create an animation GMS CHAPTER MT3DMS Conceptual Model Approach MT3DMS simulations can be constructed using either the grid approach where data are entered on a cell by cell basis or using the conceptual model approach where the data are entered via points arcs and polygons The previous tutorial described how to use the grid approach This tutorial describes how to use the conceptual model approach 7 1 Description of Problem The problem we will be solving for this tutorial is an extension of the problem described in the tutorial entitled MODFLOW Conceptual Model Approach Thus if you have not yet completed the MODFLOW tutorial you may wish to do so now before continuing In the MODFLOW tutorial a site in East Texas was modeled We will be using the solution from this model as the flow field for the transport simulati
62. 000 ft The grid will consist of 15 rows and 15 columns each cell measuring 5000 ft by 5000 ft in plan view For simplicity the elevation of the top and bottom of each layer will be flat The hydraulic conductivity values shown are for the horizontal direction For the vertical direction we will use some fraction of the horizontal hydraulic conductivity 2 2 GMS Tutorials Volume Flow into the system is due to infiltration from precipitation and will be defined as recharge in the input Flow out of the system is due to buried drain tubes discharging wells not shown on the diagram and a lake which is represented by a constant head boundary on the left Starting heads will be set equal to zero and a steady state solution will be computed Const Head 0 ft Recharge 0 003 ft d in column 1 of ae layers 1 amp 2 rain E Layer 1 50 ft d top elev 200 ft bot elev 150 ft Layer 2 K 3 ft d top elev 150 ft bot elev 400 ft Layer 3 K 7 ft d top elev 400 ft bot elev 700 ft Figure 2 1 Sample Problem to be Solved 2 2 Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state 23 Required Modules Interfaces You will need the following components enabled to complete this tutorial MODF
63. 2 Conclusion This concludes the Managing Transient Data tutorial Here are the things that you should have learned in this tutorial e When you bring up the properties dialog for objects in the Map module you can enter transient data by using the 2 button e You can import transient pumping data for wells and transient observation data The wells or observation points must already exist e GMS can show dates and times as scalar values 0 0 2 5 etc or in date time format 12 03 2003 You must define your MODFLOW stress periods before you use the Feature Objects Map gt MODFLOW MODPATH command CHAPTER 12 Stochastic Modeling Parameter Randomization There is always a significant amount of uncertainty associated with a groundwater model This uncertainty can be associated with the conceptual model or with the data and parameters associated with the various components of the model Some model parameters such as hydraulic conductivity and recharge are particularly prone to uncertainty Calibrating a model to a rich set of observation data monitoring wells stream flows etc may reduce this uncertainty somewhat However calibration data are often scarce and even well calibrated models have a high level of uncertainty One method for dealing with uncertainty is to utilize a stochastic modeling approach With a non stochastic approach a single model is developed that represents the best estimate of the real system be
64. 99 14 48 32 838 NNWAU The name column must be included This tells GMS how to link the transient observation data to the points in the observation coverage The last column in the header line defines the name of the measurement This measurement should be turned on in the Coverage Setup dialog before the first file is imported As each line is imported the matching observation point is found and the observed head is added to the time series for the point This file should have the extension txt The file is imported through the Open command in the File menu dialog Managing Transient Data 11 11 To import the file 1 2 N Switch to the Map module Double click on the Observation Wells coverage in the Data Tree In the column of Obs Points attributes turn on the Trans Head attribute and click OK Select the Open button gt the Open dialog change the Files of type selection to Text Files txt Select the file named trans_obs txt Select the Open button In the File Import Wizard turn ON the Heading row option Under the Set the column delimiters section turn OFF the Space option Click Next Set the GMS data type to Transient observation data In the trans_head column set the Type to Obs Trans Head and click Finish Now we have to re run MODFLOW 2 3 4 Switch to the 3D grid module Select the Save button Select the MODFLOW Run MODFLOW command When MOD
65. DFLOW 2000 PES Process we will use the zonal approach This involves identifying polygonal zones of hydraulic conductivity and recharge marking the zones as parameters and assigning a starting value for each zone The PES Process will then adjust the K or recharge values assigned to the zones as it attempts to minimize the residual error between computed vs observed heads and flows In the second part of this tutorial we will use the pilot point method in conjunction with PEST to parameterize hydraulic conductivity With the pilot point method we define a set of scatter points where the hydraulic conductivity is assigned Each point acts as an independent parameter and the K values for the grid are interpolated from the pilot points The pilot point method allows for a more continuous and potentially more complex distribution of values throughout the model domain It also alleviates the modeler from having to define the distribution of the zones a process that can be difficult given limited data and is often done in an arbitrary manner 9 6 Defining the Parameter Zones 9 6 1 For our first attempt at parameter estimation with the MODFLOW 2000 PES Process we will define a set of parameter zones The conceptual model approach utilized in GMS is ideally suited for this task since the conceptual model consists of recharge and K zones defined with polygons We will mark the polygons as parameter zones by assigning a key value to each pol
66. ECHARGE CONCENTRATION 22 2 10 00 2 04 40000010000000000000000000 7 6 7 9 CONVERTING THE CONCEPTUAL MODEL 2 2 2 022 2 00000000000000000 7 6 7 10 LAYER THICKNESSES 22 7 6 EE 7 7 720 THE DISPERSION PACKAGE 7 7 7 13 THE SOURCE SINK MIXING PACKAGE 06 2 2 22 0 000000000000000000000000550505000 7 7 SAVING THE SIMULATION A woe VRE AR ow ew es 7 7 LIS RUNNING 7 8 7 16 8 2 222 0 0000000000000000000000 00 7 8 RIT VIEWING THE SOLUTION a 7 8 7 18 VIEWING AN 22 2 4 41 0 00000000000000000000000000000000000 aE aa aaie a 7 9 RII MODELING SORPTION AND DECAY 7 10 7 19 1 Turning on the Chemical Reactions Package 7 10 7 19 2 Entering the Sorption Biodegradation
67. FLOW finishes running select Close The observation targets should now appear Notice that if you change the time step in the Data Tree the observation targets are updated accordingly 11 11 3 Creating Transient Observation Plots Finally we will create two types of plots to view our transient observation data The first plot is the Error vs time step plot This plot displays the mean error me mean absolute error mae and the root mean squared error rms as a function of time 1 Select the Plot Wizard button 11 17 GMS Tutorials Volume 2 3 4 Change the plot type to Error vs Time Step Select the Next button Select the Finish button to exit the dialog The plot shows that the error between the observed and computed values decreases slightly with time The second type of plot that is useful for transient observation data is the time series plot 1 2 Select the Plot Wizard button Change the plot type to Time Series Select the Next button Toggle on points Point 8 and Point 10 Turn on the Calibration Target toggle Select the Finish button to exit the dialog Wells to select Figure 11 3 Observation Wells Managing Transient 11 13 Notice the dashed lines next to each curve These dashed lines match the interval defined for each observation point This makes it so you can easily see where the computed values fall within the observation target 11 1
68. Groundwater Modeling System TUTORIALS r 1 K 50 ft d top elev 200 ft bot elev 150 ft 3 v 150 r 2 K 3 ft d top ele ft bot elev 400 ft ft d top elev 400 ft bot elev 700 ft Sheet Pile Silty Sand ky 100 11 0 Clay Blanket 32 0 ft 11 0 ft 32 0 ft PCE TCE gt Ground Water Spill Flow Direction Monitoring well locations Volume Il e MODFLOW MODPATH MT3D Analytic Element Modeling with MODAEM Calibration Transient Data Stochastic Modeling GMS version 5 0 Automated Parameter Estimation Regional to Local Model Conversion Environmental Modeling Research Laboratory GMS 5 0 Tutorials Copyright 2003 Brigham Young University Environmental Modeling Research Laboratory All Rights Reserved Unauthorized duplication of the GMS software or user s manual is strictly prohibited THE BRIGHAM YOUNG UNIVERSITY ENVIRONMENTAL MODELING RESEARCH LABORATORY MAKES NO WARRANTIES EITHER EXPRESS OR IMPLIED REGARDING THE PROGRAM GMS AND ITS FITNESS FOR ANY PARTICULAR PURPOSE OR THE VALIDITY OF THE INFORMATION CONTAINED IN THIS TUTORIAL DOCUMENT The software GMS is a product of the Environmental Modeling Research Laboratory EMRL of Brigham Young University emrl byu edu Last Revision September 7 2004 5 1 INTRODUC FION civ
69. JECT AND RUNNING MODFLOW 2 2 241222 22 000000100000 12 7 12 11 READING IN AND VIEWING THE MODFLOW SOLUTIONS 12 8 12 12 MT3DM Sr eee 12 8 12 13 READING IN THE MT3DMS 12 9 12 14 METSDMS 12 9 12 15 SELECTING THE MODFLOW STOCHASTIC SIMULATION 22 12 9 12 16 SAVING AND RUNNING MT3DMSS IN STOCHASTIC 12 10 12 17 READING IN AND VIEWING THE MT3DMS SOLUTIONS 12 10 12 18 THRESHOLD ANALYSIS aren ipin tee EEE E 12 10 12 19 EEEN A E T 12 12 13 STOCHASTIC MODELING INDICATOR SIMULATIONS eesseessesssesccesccesccescsscseseeeseesceeee 13 1 13 2 SDESERIPTION OF PROBLEM 13 1 19 22 GETTING STARTED 13 2 13 3 13 4 13 5 13 6 13 7 13 8 13 9 13 10 13 11 Table of Contents xi REQUIRED MODULES INTERFACES ccccccssscesssecsseceseecsseceseeecseeceseeseseecseeeeseecuseseseecssseeesaecnseeessaeenes 13 3 READING INTHE PROJE C Eierne ied 13 3 DATA 13 3 SELECTING THE STOCHASTIC OPTION 13
70. Jmport Wizard turn on the Heading row option and click Next Change the GMS data type to Pumping data and click Finish Select Yes at the prompt to import the pumping data as a step function Select the Select Points Nodes tool Double click on any of the wells and note that the Flow rate says lt transient gt You may want to click on the 1 button to see the curve 10 Select OK to exit the dialog s 11 6 3 Assigning Specific Yield Next we need to assign the storage coefficient to the aquifer Since this is a 1 layer unconfined aquifer we need to assign the specific yield 1 Double click on the Hydraulic Conductivity coverage in the Data Tree to bring up the Coverage Setup dialog In the list of Areal Properties turn on Specific yield Click OK to exit the dialog Select the Select Polygon tool Select the polygons labeled and 2 in the figure below Managing Transient Data 11 7 Figure 11 2 Hydraulic Conductivity Zones 6 Select Properties button eS 7 Assign a Specific yield value of 0 20 to both polygons and select the OK button to exit the dialog 8 Repeat the same procedure with the polygons labeled 3 and 4 only this time assign a value of 0 15 for the specific yield 11 7 Initializing MODFLOW Stress Periods Before converting our conceptual model we need to set up the stress periods 11 7 1 Changing the MODFLOW Simulation to Transient First we will change the current MODFLOW simulat
71. LOW You see if these components are enabled by selecting the File Register command MODFLOW Grid Approach 2 3 2 4 Units At this point we can define the units used in the model The units we choose will be applied to edit fields in the GMS interface to remind us of the proper units for each parameter 1 Select the Edit Units command 2 For Length enter ft for feet For Time enter d for days We will ignore the other units they are not used for flow simulations 3 Select the OK button 2 5 Creating the Grid The first step in solving the problem is to create the 3D finite difference grid 1 Switch to the 3D Grid module 2 Select the Grid Create Grid command 3 Select the section entitled X dimension enter 75000 for the Length value and 15 for the Number cells value 4 In the section entitled Y dimension enter 75000 for the Length value and 15 for the Number cells value 5 In the section entitled Z dimension enter 15000 for the Length value and 3 for the Number cells value Later we will enter the top and bottom elevations for each layer of the grid Thus the thickness of the cells in the z directions you enter here will not affect the MODFLOW computations The dimension we have entered was chosen to make the cells appear square when displayed prior to entering the layer elevation data 6 Select the OK button The grid should appear in your window in plan view A simplified
72. LOW Conceptual Model Approach 4 13 4 Drag a box around the entire landfill polygon rectangle thus selecting all the vertices 5 Select the Feature Objects Vertices lt gt Nodes command 6 Select the Select Points Nodes tool 7 Select one of the nodes that at the corner of the rectangle 8 While the node is selected enter the exact coordinates of the node in the Edit Window Select the Tab key after entering each coordinate value 5 2 2 it 8810 4760 9640 4760 22 8810 3960 9640 3960 Figure 4 6 Landfill 9 Repeat this process for the remaining corners of the landfill polygon 4 9 3 Building the Polygons Now that the arcs are defined we can build the polygons 1 Select the Feature Objects Build Polygons command in 4 9 4 Assigning the Recharge Values Now that the recharge zones are defined we can assign the recharge values We will assign one value to the landfill polygon and another value to the remaining polygon 1 Select the Select Polygons tool 2 Double click on the landfill polygon 3 Change the Recharge rate to 0 0002 4 14 GMS Tutorials Volume Note This recharge rate is small relative to the rate assigned to the other polygons The landfill will be capped and lined and thus will have a small recharge value The recharge essentially represents a small amount of leachate that esc
73. MS Tutorials Volume 4 Select the Packages button and select the MF2K PES Process in the Parameter Estimation Engine section of the packages dialog Select OK to exit the dialog 9 8 Starting Head The head contours currently displayed on the grid are from a forward run of a MODFLOW simulation using the starting parameter values Before running the PES process we will copy the computed heads to the Starting Heads array This will ensure that each time PES runs MODFLOW the starting head values will be reasonably close to the final head values and MODFLOW should converge quickly 1 Select the Starting Head button 2 Select the 3D Data Set gt Grid command 3 Select the bigval HEADS data set and click OK 4 Select the OK button to exit the Starting Head dialog 5 Select the OK button to exit the Global Options dialog 9 9 Editing the Parameter Data Next we will create a list of parameters and enter a starting minimum and maximum value for each 1 Select the VODFLOW Parameters command The Parameters section of this dialog is used to manage a list of the parameters used by the inverse model The New button can be used to create a set of parameters one at a time Each parameter has several properties including a name a key value a type a starting value a minimum value a maximum value a usage field and a log transform field Rather than creating each parameter one at a time in most cases the parameter list
74. MS Tutorials Volume 6 5 2 The Basic Transport Package The MT3DMS Basic Transport package is always required and it defines basic information such as stress periods active inactive regions and starting concentration values Species Since MT3DMS is a multi species model we need to define the number of species and name each species We will use one species named tracer 1 Select the Define Species button 2 Select the New button 3 Change the name of the species to tracer 4 Select the OK button Packages Next we will select which packages we wish to use 1 Select the Packages button 2 Turn on the following packages e Advection Package e Dispersion Package Source Sink Mixing Package 3 Select the OK button Stress Periods The next step is to set up the stress periods The flow simulation was steady state but the transport simulation will be transient We will run the simulation for a one year time period To do this we will use a single stress period since the input values are constant and allow MT3DMS to determine the appropriate transport step size 1 Select the Stress Periods button 2 Change the Length field to 365 3 Make sure the value in the Trans step size is 0 0 A value of zero signifies that MT3DMS will automatically compute the appropriate transport step size 4 Select the OK button to exit the Stress Periods dialog 6 5 3 MT3DMS Grid Approach 6 5 Output Contr
75. OK to exit the dialog Select the Select Points Nodes tool Select both nodes on the northern specified head arc select more than one node you can hold the shift key down while you click or you can drag a box around both nodes Select the Properties button ES In the Head field for both nodes enter 182 0 3 14 GMS Tutorials Volume 13 Repeat steps 10 12 for the nodes attached to the southern specified head arc and enter 178 6 for the head value 3 10 Entering the Aquifer Properties Next we will enter the properties of our aquifer Aquifer properties can be assigned to individual polygons and we can also define properties for a background aquifer 1 Select the Global Options command 2 In the Background aquifer properties section enter 170 0 for the Base and 60 0 for the Hyd cond 3 Select OK to exit the dialog With a boundary coverage we must also have a single polygon that defines the aquifer we are modeling 4 Select the Feature Objects Build Polygons command 3 11 Saving the Project We are now ready to run MODAEM With other models in GMS like MODFLOW for example you must first save your changes to the project before you run the model When you run MODAEM however the data currently in memory is written to temporary files that MODAEM reads to compute its solution Therefore you don t have to save your changes in GMS before running MODAEM However it s a good idea t
76. OW Conceptual Model Approach tutorial This is a two layer model representing an aquifer in East Texas see Figure 4 1 The model is bounded on the bottom and right sides by rivers represented with specified head boundaries and on the north by a no flow boundary corresponding to a bedrock outcropping The model includes two extraction wells and three drains The model was developed to analyze the long term consequences of a proposed landfill For this tutorial we will randomize the recharge the leakage from the landfill and the hydraulic conductivity associated with the top layer After developing multiple MODFLOW simulations using the Latin Hypercube sampling method we will then simulate the contaminant transport resulting from each flow model using MT3DMS Finally we will process the results using the threshold analysis option in the GMS Risk Analysis Wizard 12 2 Random Sampling vs Latin Hypercube GMS provides two methods for performing parameter randomization Random Sampling and Latin Hypercube With the Random Sampling method the user specifies a mean a standard deviation a minimum value and a maximum value for each parameter In addition the parameter can be specified as log transformed which is typically the case for hydraulic conductivity The user also specifies the number of simulations For each simulation a random number is generated for each parameter according to the specified distribution using the mean standard de
77. PES process but only PEST includes regularization thus allowing you to have more pilot points When PEST or MF2K PES finishes the solution imported into GMS corresponds to the optimal input values However the input values in GMS are still the starting values You must use the Import Optimal Values button to replace the starting values with the optimal values You use 2D scatter points to create pilot points in GMS When you are using pilot points and you select the Import Optimal Values button a new data set is created for the 2D scatter points You then need to interpolate from the scatter points to the grid if you want to see what the array of optimal values is 10 Regional to Local Model Conversion For many modeling studies determining an appropriate set of boundary conditions can be difficult It is often the case that classical boundaries such as rock outcroppings rivers lakes and groundwater divides may be located at a great distance from the site of interest In such cases it is often convenient to perform the modeling study in two phases In the first phase a large regional scale model is constructed and the model is extended to well defined boundaries During the second stage a second smaller local scale model is constructed that occupies a small area within the regional model The groundwater elevations computed from the regional model are applied as specified head boundary conditions to the local sc
78. S provides two methods for assigning observed flow to individual arcs or to a group of arcs The stream flow that was measured at the site represents the total flow from the aquifer to the stream at the stream outlet at the top of the model This flow represents the flow from the aquifer to the stream for the entire stream network Thus we need to assign the observed flow to a group of arcs When reading a solution GMS will then automatically sum the computed flow for all arcs in the group Before assigning the observed flow we must first create an arc group 8 8 GMS Tutorials Volume 1 In the Data Tree right click on the Sources amp Sinks coverage and select the Coverage Setup command 2 In the list of Sources Sinks BCs toggle on the Observed Flow row 3 Select OK to exit the dialog 4 Select the Select Arcs tool 5 While holding down the Shift key click on each of the river arcs 6 Select the Feature Object Create Arc Group command This creates a new object out of the selected objects We can now assign an observed flow to the arc group 1 Select the Select Arc Groups tool 2 Double click on any of the river arcs 3 Turn on the Obs flow option 4 Inthe Obs flow rate field enter a value of 164000 for the Flow 5 Enter a value of 7500 for the Obs Flow int The values we entered indicate that to achieve calibration the computed flow should be between 156500 and 171500 ft day 164000 7500
79. Switch back to the top layer by selecting the up arrow f 4 16 Converting the Conceptual Model We are now ready to convert the conceptual model from a high level feature object based definition to a grid based MODFLOW numerical model N 1 Switch to the Map module 2 Select the Feature Objects gt MODFLOW MODPATH command 3 Make sure the All applicable coverages option is selected and select OK Notice that the cells underlying the drains wells and specified head boundaries were all identified and assigned the appropriate sources sinks The heads and elevations of the cells were determined by linearly interpolating along the specified head and drain arcs The conductances of the drain cells were determined by computing the length of the drain arc overlapped by each cell and multiplying that length by the conductance value assigned to the arc In addition the recharge and hydraulic conductivity values were assigned to the appropriate cells MODFLOW Conceptual Model Approach 4 21 4 17 Checking the Simulation At this point we have completely defined the MODFLOW data and we are ready to run the simulation Let s run the Model Checker to see if GMS can identify any mistakes we may have made the Model Checker is explained in more detail in the MODFLOW Grid Approach tutorial 1 Switch to the 3D Grid module 8 2 Select the MODFLOW Check Simulation command 3 Select the Run Check button There should be no er
80. The edit field in the upper left corner of the dialog can be used to change the current layer For our problem we need all of the values in the array to be greater than zero except for the left column of the top two layers which should be less than zero By default the values in the array should already be greater than zero Therefore all we need to do is change the values for the constant head cells This can be accomplished by entering a value of 1 for each of the thirty constant head cells However there is another way to edit the IBOUND array that is much simpler for this case This method will be described later in the tutorial For now we will leave all of the cells active 6 Select the OK button to exit the ROUND dialog MODFLOW Grid Approach 2 5 Starting Heads The next step is to set up the Starting Heads array 7 Select the Starting Heads button The Starting Heads array is used to establish an initial head value when performing a transient simulation Since we are computing a steady state simulation the initial head for each cell shouldn t make a difference in the final solution However the closer the starting head values are to the final head values the more quickly MODFLOW will converge to solution Furthermore for certain types of layers if the starting head values are too low MODFLOW may interpret the cells as being dry For the problem we are solving an initial value of zero everywhere should suffice Th
81. There are also two production wells in the area that will be included in the model NOTE Although the site modeled in this tutorial is an actual site the landfill and the hydrogeologic conditions at the site have been fabricated The stresses and boundary conditions used in the simulation were selected to provide a simple yet broad sampling of the options available for defining a conceptual model 4 2 Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state 43 Required Modules Interfaces You will need the following components enabled to complete this tutorial Grid Geostatistics Map MODFLOW You can see if these components are enabled by selecting the File Register command 4 4 Importing the Background Image 4 4 1 The first step in setting up the simulation is to import a digital image of the site being modeled This image was created by scanning a portion of a USGS quadrangle map on a desktop scanner The image was imported to GMS registered and a GMS project file was saved To read in the image we will open the project file Once the image is imported to GMS it can be displayed in the background as a guide for on screen digitizing and placement of model features Reading the Image To import the image 4 4 GMS Tutorials Volume 17 Select the Open button
82. This completes the definition of the Basic Transport package data 1 Select the OK button to exit the Basic Transport Package dialog The Advection Package The next step is to enter the data for the Advection package We want to use the Third Order TVD scheme ULTIMATE solution scheme This is the default so we don t need to do anything 6 6 GMS Tutorials Volume 6 5 4 Dispersion Package Next we will enter the data for the Dispersion package 1 2 Select the MT3D Dispersion Package command Select the Longitudinal Dispersivity button Select the Constant gt Grid option Enter a value of 20 Select the OK button Select the OK button to exit the Longitudinal Dispersivity dialog Enter a value of 0 2 for the Ratio of transverse dispersivity to longitudinal dispersivity parameter Enter a value of 0 2 for the Ratio of vertical dispersivity to longitudinal dispersivity parameter Select the Close button to exit the Dispersion Package dialog 6 5 5 The Source Sink Mixing Package Finally we must define the data for the Source Sink Mixing package For our problem we only have one source sink the injection well To define the source at the injection well we need to select the well and assign a concentration 1 Select the cell containing the injection well the upper well by clicking anywhere in the interior of the cell 2 Select Point Sources Sinks command 3 Turn on the W
83. actly at the center of the element For example consider Figure 3 3 a below with a single constant head line sink with a head of 99 m 3 6 3 2 GMS Tutorials Volume II Figure 3 3 a Line sink b Line sink with extra vertices for better resolution As you see the head is matched only at the center of the element and the heads vary along the single element Now see the result when the single specified head line sink is replaced by ten line sinks as shown in Figure 3 3 b This is clearly what the modeler intended the head along the line sink string is 99 m It is up to the modeler to determine what resolution each string of line sinks needs for a particular problem think of the length of line sinks in the same way you think of MODFLOW cell sizes Fortunately GMS provides a handy facility for adding and removing vertices along line segments and adjusting the resolution along a string of elements The same rules apply for other line elements in MODAEM including horizontal barriers and inhomogeneity boundaries You will often wish to use GMS s Distribute Vertices command to ensure accurate solutions for heterogeneous aquifers Line sinks versus inhomogeneities Recall from above that each line segment along a lone sink string has a constant sink density If a string of line sinks crosses a sub domain boundary it is expected that there will be a jump in the sink density at the boundary For an
84. ake Layer 2 the active coverage by selecting it in the Data Tree Double click on the layer polygon For the Porosity enter a value of 0 4 For Long Disp enter a value 20 7 6 GMS Tutorials Volume 5 6 Select the OK button Click anywhere outside the model to unselect the highlighted polygon 7 8 Assigning the Recharge Concentration The purpose of our model is to simulate the transport of contaminants emitted from the landfill When the flow model was constructed a separate reduced value of recharge was assigned to the landfill site This recharge represents leachate from the landfill We will assign a concentration to this recharge The concentration can be assigned directly to the recharge polygon in the conceptual model 1 In the Data Tree right click the Recharge coverage and select the Coverage Setup command from the pop up menu From the list of Areal Properties turn on Recharge conc and click OK Double click on the landfill polygon For the leachate Recharge conc enter a constant value of 20000 for the concentration Select the OK button Click anywhere outside the model to unselect the polygon 7 9 Converting the Conceptual Model At this point we are ready to assign the aquifer parameters and the recharge concentration to the cells using the conceptual model 1 2 Select the Feature Objects Map gt MT3DMS command Make sure the All applicable coverages option is selected a
85. ale model The layer data including elevations and transmissivities are also interpolated from the regional to the local model A more detailed representation of the local flow conditions including low capacity wells and barriers not included in the regional flow model can be constructed in the local scale model Regional to local model conversion is often referred to as telescopic grid refinement GMS provides a convenient set of tools that can be used for regional to local model conversion The steps involved in a typical regional to local model conversion using MODFLOW are described in this tutorial 10 1 Description of Problem The site we will be modeling in this tutorial is shown in Figure 10 1 The main features of the regional model are shown Most of the boundaries are no flow boundaries corresponding to groundwater flow divides bedrock outcroppings and natural flow boundaries A river runs through the left side of the model The narrow regions where the river enters and exits the model are modeled as 10 2 GMS Tutorials Volume II specified head boundaries There are four major production wells in the region The site will be modeled using two layers a lower confined layer and an upper unconfined layer The local site is situated in the interior of the model The local site corresponds to a chemical plant with a small spill Once the regional model is completed a local scale model is to be developed and then used to anal
86. analytic solutions may be superimposed to provide a solution for more complex problems for example two wells pumping near one another as shown in Figure 3 1 b below MODAEM 3 3 b Figure 3 1 a Well b Two wells illustrating superposition In addition to wells MODAEM makes use of line sink elements to represent surface waters or other linear infiltration features Figure 3 2 a and area sink elements for recharge from rainfall infiltration ponds and other features Figure 3 2 b Figure 3 2 a Line sink b Area sink 3 4 GMS Tutorials Volume Although MODAEM is limited to a single aquifer the aquifer may be heterogeneous The aquifer can be divided into sub domains with each sub domain having a different hydraulic conductivity base elevation thickness and or porosity About the mathematics of analytic elements It is not necessary for the new modeler to understand all of the mathematics behind the AEM There is one important point to discuss in general terms the discharge potential MODAEM does not formulate the groundwater problem in terms of the potentiometric head but instead in terms of a discharge potential which combines the hydraulic conductivity aquifer geometry and head into one value At any point in a MODAEM model the discharge potential and the head are related by one of the following for confined flow and 1 2 2 for unconfined flow where is the
87. apes from the landfill 4 5 6 7 Select the OK button Double click on the outer polygon Change the Recharge rate to 0 0228 Select the OK button 4 10 Defining the Hydraulic Conductivity Next we will enter the hydraulic conductivity for each layer In many cases you may wish to define multiple polygons defining hydraulic conductivity zones For the sake of simplicity we will use a constant value for each layer 4 10 1 Copying the Boundary We ll create our recharge coverage by copying the boundary 1 Right click on the Boundary coverage and select the Duplicate command from the pop up menu Change the name of the new coverage to Layer 1 Right click on the Layer 1 coverage and select the Coverage Setup command In the Areal Properties list turn ON the following options Horizontal K Vertical anis Change the Default layer range to go from 1 to 1 Select the OK button Right click on the Layer 1 coverage and select the Duplicate command from the pop up menu Change the name of the new coverage to Layer 2 Right click on the Layer 2 coverage and select the Coverage Setup command Change the Default layer range to go from 2 to 2 Select the OK button MODFLOW Conceptual Model Approach 4 15 4 10 2 Top Layer First we will assign a K value for the top layer 1 Select the Layer 1 coverage in the Data Tree 2 Select the Feature Objects Build Polygons command 3 With the Select Polyg
88. arameters must be less than the number of observations With regularization the number of parameters can greatly exceed the number of observations As a result complex hydraulic conductivity distributions can be defined resulting in extremely low residual error The pilot point method with regularization is an incredibly powerful feature of PEST 9 15 Selecting PEST as the Inverse Model We will now use PEST to calibrate the model 1 Select the VODFLOW Global Options command Automated Parameter Estimation 9 11 Select the Packages button In the Parameter Estimation Engine section of the dialog under the select PEST Select OK twice to exit both dialogs 9 16 Creating Pilot Points Next we will create the pilot points that define the hydraulic conductivity distribution for our model The pilot points are defined as 2D scatter point sets in GMS We will create about 15 points In a normal case we may use 50 or more points However additional points slow down the calibration process and 15 points are adequate to illustrate the process with this particular model 1 2 Switch to the 2D Scatter Point module Bi Select the Scatter Points New Scatter Point Set command Enter HK as the name and select the OK button Select the Scatter Points Scatter Point Set Options command Enter 5 for the Default data set value and select the OK button Select the Create Vertex tool 9 12 GMS Tutorials Volume
89. asin is shown in Figure 8 1 The basin encompasses 28 square miles It is in a semi arid climate with average annual precipitation of 1 25 ft yr Most of this precipitation is lost through evapotranspiration The recharge which reaches the aquifer eventually drains into a small stream at the center of the basin This stream drains to the north and eventually empties into a lake with elevation 1000 ft Three wells in the basin also extract water from the aquifer The perimeter of the basin is bounded by low permeability crystalline rock There are ten observation wells in the basin There is also a stream flow gauge at the bottom end of the stream 8 2 GMS Tutorials Volume Model Boundaries amp Stresses Head 1000 ft x Well 1 x Well 2 x Well 3 Stream Figure 8 1 Sample Model Used in Calibration Exercise The assumed recharge and hydraulic conductivity zones for the model are shown in Figure 8 2 The model region encompasses fractured and weathered bedrock as well as alluvial material grading from hydraulically tighter materials in the south to more permeable materials in the north Furthermore the materials around the stream tend to be coarser cleaner and thus more permeable The topmost region of the model near the lake has a high level of phreatophytic plant life The first task of this exercise will be to import a single layer unconfined MODFLOW model that has been constructed for the site This model co
90. be entered by hand However we will import the well data from a text file This method is particularly useful for models with lots of wells and or complicated pumping schedules Pumping well data is typically imported using two files The first file contains the name screen geometry and xy coordinates of the wells The second file contains the pumping schedules Since the well locations are already defined we only need to import the pumping schedules The format for this file is as follows Name date time Q well 1 12 3 1999 18 00 00 625 0 well 1 1 30 2000 7 38 25 0 0 well 1 3 27 2000 18 00 00 200 0 well 2 12 3 1999 18 00 00 0 0 well 2 12 5 1999 14 48 32 100 0 The name column must be included This tells GMS how to link the transient pumping data to the wells in the map module The first time an entry is found for a particular well if the well is steady state it is changed to transient and a pumping rate time series is created for the well Each time a subsequent line is read with the same well name GMS adds a point to the time series The dates and times can be in any standard format To import the well pumping data file 1 Select the Sources amp Sinks coverage from the Data Tree to make it the active coverage 2 Select the Open button a 3 In the Open dialog change the Files of type selection to Text Files txt 11 6 GMS Tutorials Volume II Select the file named pumping txt and click Open In the
91. bled to complete this tutorial Grid Map MODFLOW MODPATH You can see if these components are enabled by selecting the File Register command 5 4 Importing the Project The first step is to import the East Texas project This will read in the MODFLOW model and solution and all other files associated with the model To import the project 1 Select the Open button gt 2 the Open dialog locate and open the directory entitled tutfiles modfmap sample 3 Select the file entitled sample gpr 4 Choose the Open button If the MODPATH component has been licensed and enabled the MODPATH menu becomes available whenever you have a MODFLOW simulation in GMS Thus at this point we are ready to create particles First however we will look at the porosity 5 5 Assigning the Porosities In order to calculate the tracking times a porosity value must be defined for each of the cells in the grid By default GMS automatically assigns a porosity of 0 3 to all the cells in the grid This value is acceptable so we don t need to do anything MODPATH 5 3 If we did want to change the porosity we could do it in a number of ways The first way is to assign porosities to the polygons in the conceptual model and selecting the Map gt MODFLOW MODPATH command The second way is to select the Porosity Array command from the MODPATH menu in the 3D Grid module This allows you to edit a spreadsheet of values Another way is the select g
92. button 12 14 MT3DMS Model The MT3DMS model we have imported is a simple transport model with a concentration assigned to the recharge at the cells in the location of the landfill The initial concentration for the entire model is set to zero All of the other sources sinks have a zero concentration The simulation is set to run for 3000 days with output every 300 days The leachate plume should migrate to the south and be captured by the well or the river or both 12 15 Selecting the MODFLOW Stochastic Simulation The MT3DMS model is already set up for us but we still need to specify that we want to run MT3DMS in batch mode with our stochastic MODFLOW solution 1 From the MT3D Run Options command 2 Select the Batch run with selected MODFLOW solution set option We currently have only one MODFLOW solution set in GMS so mfsto MODFLOW STO should appear in the combo box below the selected radio button 3 Select the OK button to exit the dialog 12 10 GMS Tutorials Volume 12 16 Saving and Running MT3DMS in Stochastic Mode We are now ready to save the project and MT3DMS using the MODFLOW stochastic results 1 Select the File Save As command Note that we can specify different names for the MODFLOW and MT3DMS model files using the controls at the bottom of the dialog However in this case we will use the default names 1 Select the Save button 2 Select Yes to overwrite the existing project 3 S
93. ce for GMS is divided into eleven modules Some of the modules contain interfaces to models such as MODFLOW Such interfaces are typically contained within a single menu Since some users may not require all of the 1 2 GMS Tutorials Volume of the modules or model interfaces provided in GMS modules and model interfaces can be licensed individually Modules and interfaces that have been licensed are enabled using the Register command in the File menu The icons for the unlicensed modules or the menus for model interfaces are dimmed and cannot be accessed GMS provides two modes of operation demo and normal In normal mode the modules and interfaces you have licensed are undimmed and fully functional and the items you have not licensed are dimmed and inaccessible In demo mode all modules and interfaces are undimmed and functional regardless of which items have been licensed However all of the print and save commands are disabled The modules and interfaces needed for the tutorial are listed at the beginning of each tutorial While some of the tutorials may be completed in either normal or demo mode many of them can only be completed in normal mode If some of the required items have not been licensed you will need to obtain an updated password or hardware lock before you complete the tutorial Format Throughout the tutorials interface objects like menus or buttons are shown in italics Menu commands are given by specifying t
94. ct the Duplicate command from the pop up menu 3 Rename the new particle set 1000 days 4 Right click on the 1000 days particle set and select the Properties command from the pop up menu 5 Change the Duration of the 1000 days particle set to 1 000 and click OK 5 6 GMS Tutorials Volume 5 8 3 Changing the Display Order The order of the particle sets in the Data Tree is the order in which they are displayed Thus the particle sets listed on top in the spreadsheet will be displayed on top of the ones underneath You can drag the particle sets up and down to change their order Since the 1 000 day capture zone is smaller than the 3 000 day capture zone we needed to make sure that it is displayed on top 1 In the Data Tree drag the 1 000 days particle set up so it is above the 3 000 days particle set You should now see two capture zones the larger one being the 3 000 day capture zone and the smaller one being the 1 000 day capture zone 5 9 Tracking Particles from the Landfill Next we will perform forward tracking from a set of starting locations which coincide with the site of the proposed landfill 5 9 1 Creating a New Particle Set Create a new particle set for the particles we will create at the landfill 1 In the Data Tree right click on the Particle Sets folder and select the New Particle Set command 2 Change the name of the new particle set to Landfill 3 Right click on the Landfill particle s
95. ct the Open button You should see a one layer MODFLOW model rotated at a 40 degree angle showing a four material distribution To view the material sets generated by T PROGS 1 Expand the Material Sets folder in the Data Tree 2 Expand the Simulation folder 3 Click on any of the material sets labeled Simulation X You may wish to use the up and down arrow keys on your keyboard to cycle through the material sets 13 5 The MODFLOW Model Data Most of the MODFLOW data for our model boundary conditions well pumping rate top and bottom elevations etc has already been entered However we will review some of the MODFLOW data that are somewhat more unique to this type of simulation 1 Select MODFLOW LPF Package command 13 4 GMS Tutorials Volume At the top of the dialog notice that the Use material ids option is selected for the Layer property entry method This means that we will not enter an array of K hydraulic conductivity values as is normally the case with MODFLOW Rather we will use material ids to define the K values 2 Select the Material IDs button This dialog illustrates the material IDs assigned to cells These material 105 are inherited from the active material set generated by T PROGS 3 Select the OK button to exit the Material IDs dialog 4 Select the Material Properties button This dialog is used to assign aquifer properties including hydraulic conductivity to each of the mat
96. d type the coordinates 2741 4673 in the X and Y edit fields at the top of the GMS window and hit the Tab or Enter key 4 Select Properties button ES 5 For the Type select the well option 6 Enter a constant value of 24100 for the flow pumping rate 7 Change the From layer and To layer properties to be 1 This means the well will only be in layer 1 of the grid 8 Select the OK button 9 Ina similar fashion create the other well at the location 10557 3290 and assign a pumping rate of 100 000 However for this well change the From layer and To layer so that the well is applied only to layer two change both the edit fields to 2 Grid Refinement A well represents a point of convergence in the groundwater flow and causes steep gradients in the head near the well In order to accurately model the flow near wells the grid is typically refined in the vicinity of the wells This type of refinement can be performed automatically in GMS by assigning refinement data directly to the wells in the conceptual model 1 Select the Select Points Nodes tool f 2 Select both wells by clicking on the wells while holding the Shift key 3 Select Properties button eS 4 17 GMS Tutorials Volume 4 Find the Refine column and in the row turn the toggle This turns on refinement for both points 5 Change the Base size to 75 the Bias to 1 1 and the Max size to 500 for both points 6 Click OK 4 9 Delineati
97. d Specified Flow 5 In the Areal Properties section of the dialog toggle on Recharge 6 Select OK to exit the dialog 7 Select the Select Polygons tool 8 Double click on the polygon and assign a value of 000418 to the Recharge field Click OK to exit the dialog 3 16 Running MODAEM We are now ready to run MODAEM again 1 Hit the F5 key 2 When MODAEM is finished select the Close button 3 17 Production Wells Now we will import production wells from a tab delimited text file 1 Right click on Indiana in the Data Tree and select the New Coverage option 3 18 GMS Tutorials Volume 10 11 12 Change the name of the coverage to Wells Under the Source Sink BCs section toggle on the Wells option Select OK to exit the dialog Select the Open button gt Locate and open the directory entitled tutfiles modaem Select and open the file prod_wells txt Toggle on the Heading row toggle Click the Next gt button Change the GMS data type to Well data In the File preview section of the dialog change the Type of the first column to X the second to Y and the third to Flow Rate Select the Finish button to exit the dialog You may have difficulty seeing the wells The well symbol can be changed in the Display Options dialog by clicking on the Display macro a 3 18 Observation Wells Before running MODAEM again we will also read in field measured head values 1 Right click on Indiana
98. dle Layer Wells Next we will define some wells on the middle layer First we need to view the middle layer 1 Select the Decrement button in the Mini Grid Plot To select the cells 2 While holding down the Shift key select the cells are shown in Figure 2 4 Constant Head Cells elect these 9 9 9 9 oe eo eo ojo Figure 24 Cells to be Selected on Middle Layer 3 Select Sources Sinks command 4 Select the Well tab 5 Select the New button 6 Enter a Flow value of 432 000 for both wells MODFLOW Grid Approach 2 13 7 Select the OK button 8 Unselect the cells by clicking anywhere outside the grid 2 11 3 Bottom Layer Well Finally we will define a single well on the bottom layer To view the bottom layer 1 Select the Decrement button in the Mini Grid Plot 2 Select the cell is shown in Figure 2 5 Select this col i 11 row i 5 lay k 3 Figure 2 5 Selected on Bottom Layer 3 Select the MODFLOW Sources Sinks command 4 Select the Well tab 5 Select the New button 6 Enter a Flow value of 5 7 Select the OK button 1 Unselect the cells by clicking anywhere out
99. e Sink Coverage The next step in building the conceptual model is to construct the local sources sinks coverage This coverage defines the boundary of the region being modeled and it defines local sources sinks including wells rivers drains and general head boundaries The properties which can be assigned to the feature objects in a coverage depend on the Conceptual model and the options set in the Coverage Setup dialog Before creating the feature objects we will change the options in the Coverage Setup dialog 1 Right click on the Boundary coverage and select the Duplicate command from the pop up menu Change the new coverage name to Sources Sinks 2 Right click on the Sources Sinks coverage and select the Coverage Setup command from the pop up menu 3 For the Preset select the Source sink coverage option This turns on a number of standard source sink type properties 4 Inthe list of Sources Sinks BCs turn OFF the following options which we won t need for this tutorial Specified Flow General Head River Seepage Face MODFLOW Conceptual Model Approach 4 7 Barrier 5 Make sure the Use to define model boundary active area option 18 on 6 Click OK 4 8 1 Defining the Specified Head Arcs The next step is to define the specified head boundary along the south and east sides of the model Before doing this however we must first split the arc we just created into three arcs One arc will define the no f
100. e Starting Heads array is also used to establish the head values associated with constant head cells For our problem the constant head values are zero Since all of the starting head values are already zero by default we don t need to make any changes 8 Select the OK button to exit the Starting Heads dialog Top and Bottom Elevations The next step is to set up the top and bottom elevation arrays 1 Select the Top Elevation button 2 Make sure the Layer is 1 3 Select the Constant PLayer button 4 Enter a value of 200 and select the OK button 5 Select the OK button to leave the Top Elevations dialog GMS forces the top of a layer to be at the same location as the bottom of the layer above Thus we only need to enter the bottom elevations of all the layers now and the tops of the layers will be set automatically 1 Select the Bottom Elevation button 2 Make sure the Layer is 1 3 Select the Constant PLayer button 4 Enter a value of 150 and select the OK button 5 Change the Layer to 2 2 6 2 7 GMS Tutorials Volume 6 Select the Constant PLayer button 7 Enter a value of 400 and select the OK button 8 Change the Layer to 3 9 Select the Constant PLayer button 10 Enter a value of 700 and select the OK button 11 Select the OK button to exit the Bottom Elevation dialog 12 Select the OK button to exit the MODFLOW Global Package dialog Assigning IBOUND Values Directly to Cells As men
101. e coverage and only the active coverage can be edited CHAPTER MODFLOW Conceptual Model Approach Two approaches can be used to construct a MODFLOW simulation in GMS the grid approach or the conceptual model approach The grid approach involves working directly with the 3D grid and applying sources sinks and other model parameters on a cell by cell basis The steps involved in the grid approach are described in the tutorial entitled MODFLOW Grid Approach The conceptual model approach involves using the GIS tools in the Map module to develop a conceptual model of the site being modeled The location of sources sinks layer parameters such as hydraulic conductivity model boundaries and all other data necessary for the simulation can be defined at the conceptual model level Once this model is complete the grid is generated and the conceptual model is converted to the grid model and all of the cell by cell assignments are performed automatically The steps involved in performing a MODFLOW simulation using the conceptual model approach are described in this tutorial It is recommended that you complete Interpolating Layer Elevations and MODAEM tutorials before completing this tutorial Description of Problem The problem we will be solving for this tutorial is illustrated in Figure 4 1 The site is located in East Texas We will assume that we are evaluating the suitability of a proposed landfill site with respect to potential
102. e not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state 93 Required Modules Interfaces You will need the following components enabled to complete this tutorial Grid Geostatistics Map MODFLOW Inverse Modeling You can see if these components are enabled by selecting the File Register command 94 Reading in the Project First we will read in the modeling project 1 Select the Open button gt 2 Locate and open the tutfiles inverse directory 3 Select the file entitled bigval gpr 4 Select the Open button You should see a MODFLOW model with a solution and a set of GIS coverages Three of the coverages are the source sink recharge and hydraulic conductivity coverages used to define the conceptual model The active coverage contains a set of observed head values from observation wells If you switch to the source sink coverage you will notice that an observed flow has been assigned to the stream network as described in the previous tutorial Automated Parameter Estimation 9 3 9 5 Model Parameterization The first step in setting up the inverse model is to parameterize the input This involves identifying which parts of the model input we want the inverse model utility to optimize We will utilize two approaches for parameterization In the first attempt at parameter estimation with the MO
103. e water table or at the cell centers We will use the default and place particles at the water table We can also specify the tracking duration although for this tutorial we will be tracking the particles until they terminate To end 5 Select the Finish button At this point the wizard should go away and a progress bar should appear at the bottom When the computations are finished a new data set well will be added to the matsto MODFLOW STO folder This data set contains the probability that any particles placed at the water table will reach the well The best way to view this data set is to turn on color filled contours 6 Select the Data Contour Options command 7 Change the Contour Method to Color Fill 8 Select the Color Ramp button to bring up the Color Ramp Options dialog Stochastic Modeling Indicator Simulations 13 7 9 Turn on the Legend option 10 Select OK on both dialogs to exit You should now see a zone of probability extending from the well 13 11 Conclusion This concludes the Stochastic Modeling Indicator Simulations tutorial Here are the things that you should have learned in this tutorial e GMS supports two types of stochastic approaches parameter randomization and indicator simulations e The Risk Analysis Wizard can be used to do a probabilistic capture zone analysis
104. ed automatically 7 17 Viewing the Solution 1 In the Time Step list below the Data Tree select the last time step It is often helpful to use the color filled contours option To do this 2 Select the Data Contour Options command 3 Select the Contour specified range option 4 Enter 1 for the minimum value and 125 for the maximum MT3DMS Conceptual Model Approach 7 9 5 Change the Contour Method to Color fill 6 Select the OK button to exit the Contour Options dialog You should now see a display of color shaded contours confined to the area adjacent to the landfill Note that the leachate eventually reaches both the river and the well To view the solution for layer two 7 Select the down arrow in the mini grid display To view the solution in cross section view 8 Select the up arrow f in the mini grid display 9 Select a cell in the vicinity of the landfill 10 Select the View J Axis button ti 11 Use the left and right arrow keys to view the solution along different columns 12 Select the View K Axis button when finished 7 18 Viewing an Animation Next we will observe how the solution changes over the course of the simulation by generating an animation animation To set up the animation 1 Select the Display Animate command 2 Make sure the Data set option is on and click Next 3 Turn on the Display clock option 4 Select the Use constant interval option 5 Enter a value of 300
105. elect Run MT3D command MT3DMS is now running in stochastic mode The spreadsheet at the top shows each model and as each model run is completed the spreadsheet will update the status for the run as converged or not converged It will take several minutes for all 27 model runs to be completed 12 17 Reading in and Viewing the MT3DMS Solutions Once all the MT3DMS runs are completed you can read in the solutions as follows 1 Make sure the Read solution on exit toggle is check and select the Close button As was the case with the MODFLOW solution when the MT3DMS dialog closes another dialog appears that lists each MT3DMS solution and whether or not it converged 1 Select OK to exit the dialog You should see a new folder name mfsto UT3DMS STO appear below the MODFLOW solutions in the Data Tree window Once again you can expand this folder and click on individual solutions to see the results of the stochastic transport simulation 12 18 Threshold Analysis Now that we have imported the MT3DMS solution set we can perform a threshold analysis on the computed leachate concentrations threshold analysis can be used to generate a data set representing the probability that one or more user defined threshold conditions is satisfied For our case we want to Stochastic Modeling Parameter Randomization 12 11 generate a plot indicating the probability that the leachate concentration exceeds 10 0 To do this we
106. elect slug for the Mass units 3 Select ppm for the Concentration units 4 Select the OK button 7 6 Initializing the MT3DMS Simulation Now that the MODFLOW model is in memory we can initialize the MT3DMS simulation First we will initialize the model 7 6 1 7 6 2 7 6 3 MT3DMS Conceptual Model Approach 7 3 1 Switch to the 3D Grid module p 2 Select the MT3D New Simulation command Defining the Species Since MT3DMS is a multi species model we need to define the number of species and name each species We will use one species named leachate 1 Select the Define Species button 2 Change the name of the species to leachate 3 Select the OK button to return to the Basic Transport Package dialog Defining the Stress Periods Next we will define the stress periods 1 Select the Stress Periods button Since the flow solution computed by MODFLOW is steady state we are free to define any sequence of stress periods and time steps we wish Since the leachate from the landfill will be released at a constant rate we only need one stress period We will enter the length of the stress period i e the length of the simulation and let MT3DMS compute the appropriate transport time step length by leaving the transport step size at zero 1 Enter 3000 for the stress period length days 2 Enter 2000 for the Max transport steps 3 Select the OK button to exit the Stress Periods dialog Selecting Output
107. ell option 4 Enter a value of 57 87 for the concentration 5 Select the OK button 6 Click outside the grid to unselect the cell 6 5 6 Saving the Simulation and Running MT3DMS We are now ready to save the simulation and run MT3DMS 1 Select the Save button MT3DMS Grid Approach 6 7 2 Select the Run MT3DMS command 3 When the simulation is finished select the Close button 6 5 7 Changing the Contouring Options When displaying plume data the color fill option often provides excellent results 1 Select the Data Contour Options command 2 Change the Contour method to Color Fill 3 Select the OK button 6 5 8 Setting Up an Animation Finally we will observe how the solution changes over the one year simulation by generating an animation animation To set up the animation 1 Select the Display Animate command 2 Make sure the Data set option is on and click Next 3 Turn on the Display clock option 4 Select the Use constant interval option and change the Time interval to 36 5 This will result in 11 frames 5 Select the Finish button You should see some images appear on the screen These are the frames of the animation which are being generated 1 After viewing the animation select the Stop button to stop the animation 2 Select the Step button to move the animation frame at a time 3 You may wish to experiment with some of the other playback controls When
108. ement model is MODFLOW and with MODFLOW things are a bit different With MODFLOW you must run the simulation and read in the solution before the calibration targets appear This is because the computed values are output by MODFLOW and are not calculated internally by GMS So we will now run MODFLOW and read in the solution 8 6 GMS Tutorials Volume 8 6 4 1 Select the File Save As command 2 Enter run2 gpr for the file name 3 Select the Save button 4 Switch to the 3D Grid module 8 5 Select the VODFLOW Run MODFLOW command 6 When MODFLOW is finished running select the Close button Note that a calibration target is now drawn next to the point The components of a calibration target are illustrated in Figure 8 3 The center of the target corresponds to the observed value The top of the target corresponds to the observed value plus the interval and the bottom corresponds to the observed value minus the interval The colored bar represents the error If the bar lies entirely within the target the color bar is drawn in green If the bar is outside the target but the error is less than 200 the bar is drawn in yellow If the error is greater than 200 the bar is drawn in red Observed Interval lt 4 Computed Value Error Calibration Target 4 Observed Value Observed Interval Figure 8 3 Calibration Target Point Statistics We can view more detailed statistics concerning
109. erials used by the model As you click on each of the materials in the list you will notice that a value has been assigned for Kh and Kv for each material Since this is a one layer model Only the hydraulic conductivity value will be used When the MODFLOW model is saved to disk GMS uses the array of material IDs and the list of material properties to automatically generate the array of K values required by MODFLOW 5 Select the OK button twice to exit both dialogs 13 6 Selecting the Stochastic Option Before running MODFLOW we need to turn on the appropriate stochastic simulation options First we will select the stochastic run option 1 Select the VODFLOW Global Options command 2 In the Run Options section of the dialog select the Stochastic Simulation option 3 Choose OK to exit the dialog Next we need to specify that we will be using the material set method as opposed to parameter randomization in our stochastic simulation When we choose the material set option we must also specify which group folder of material sets we wish to use In our case we only have one group called Simulation 1 Select the VODFLOW Stochastic command 2 Select the Material sets method 3 Verify that Simulation shows up in the combo box below the Material sets option Stochastic Modeling Indicator Simulations 13 5 4 Choose OK to exit the dialog 13 7 Saving the Project and Running MODFLOW We are now ready to save the
110. et and select the Properties command 4 Make sure the direction of the Landfill particle set is Forward and click OK 5 9 2 Defining the New Starting Locations Finally we will create a new set of starting locations at the site of the proposed landfill The particles will be placed on the top of the ground water table to simulate leachate entering from the surface We ll turn off the boundary fill option so we see the new pathlines easier 1 Select the Display Options command 2 In the Capture zones section turn off the Poly fill option 3 Select the OK button MODPATH 5 7 Before selecting the cells we will make the recharge coverage the active coverage so that the landfill polygon is clearly visible 1 Switch to the Map module 2 In the Data Tree expand MODFLOW conceptual module and select the Recharge coverage To select the cells 1 Switch back to the 3D Grid module 2 Select the Select Cells tool 89 3 Select the cells covered by the landfill by dragging a rectangle that coincides with the landfill boundary 4 Select the MODPATH Generate Particles at Selected Cells command 5 Select the OK button Now you should see a set of pathlines starting at the landfill and terminating in the well the creek bed and in the river at the bottom of the model If none of your landfill pathlines go to the well you may need to add particles to the column of cells just to the right of the
111. et vies By EE tee 9 4 9 6 3 Mapping the Key Values to the Grid 9 5 9 7 SELECTING THE PARAMETER ESTIMATION 9 5 9 8 a a ei 9 6 9 9 EDITING THE PARAMETER DATA eea a aa a ae EEE 9 6 9 10 MAX ITERATIONS e en acre eae eee 9 7 9 11 SAVING THE PROJECT AND RUNNING MODFLOW 20 2 9 7 9 12 VIEWING THE SOLUTION onsere steeen niieg enas aee are E i eiae anie En EED aE Tanoe 9 8 9 13 LOADING OPTIMAL PARAMETER 9 9 a ae 9 9 9 15 SELECTING PEST AS THE INVERSE 0 14244 0000 01680000 0000000000000000005000000000000 9 10 9 16 8 9 11 9 117 0 9 12 9 17 1 Creating One Parameter 9 12 9 17 2 Editing he Parameters at nd ah ada anne 9 13 9 17 3 Limiting the Number of Parameter Estimation RUNS 9 13 9 18 SAVING THE PROJECT AND RUNNING
112. ew different columns in the grid Note that on the right side of the cross section the bottom layer pinches out and the bottom elevations are greater than the top elevations This must be fixed before running the model 4 15 6 Fixing the Elevation Arrays GMS provides a convenient set of tools for fixing layer array problems These tools are located in the Model Checker and are explained fully in the Interpolating Layer Data tutorial 1 Select the MODFLOW Check Simulation command 2 Select the Run Check button 3 Select the Fix Layer Errors button at the top of the dialog 4 20 GMS Tutorials Volume Notice that many errors were found for layer two There are several ways to fix these layers We will use the Truncate to bedrock option This option makes all cells below the bottom layer inactive 4 Select the Truncate to bedrock option 5 Select the Fix Affected Layers button it does not matter which layer is selected all layers that are affected will be fixed 6 Select the OK button to exit the Fix Layer Errors dialog 7 Select the Done button to exit the Model Checker Notice that the layer errors have been fixed Another way to view the layer corrections is in plan view 8 Switch to plan view by selecting the View K Axis button 8 9 In the mini grid display select the down arrow to view the second layer Notice that the cells at the upper Northern edge of the model in layer two are inactive 10
113. grid boundary 10 8 1 Creating the Grid Next we will create the grid 1 Select the Feature Objects Map gt 3D Grid command 2 Select OK to confirm the deletion of the current 3D grid 3 Select OK again to confirm deletion of the MODFLOW data 4 In the Create Grid dialog enter 60 for the number of cells in the x direction 50 for the number of cells in the y direction and 2 for the number of cells in the z direction 5 Select OK to create the grid You should see a grid appear You can zoom in to examine the grid 1 Select the Zoom tool 2 Drag around the grid 10 8 GMS Tutorials Volume 10 8 2 Activating the Cells Next we will inactivate the exterior cells 1 Select the Activate Cells in Coverage command from the Feature Objects menu If the arcs match the grid boundary closely you may not see any cells inactivated If however the grid extends significantly beyond the arcs some cells will be inactivated 10 8 3 Mapping the Properties Next we will convert the MODFLOW data to the grid 1 Switch to the 3D Grid module 2 Select the MODFLOW New Simulation command 3 Select OK to accept the defaults in the MODFLOW Global Basic Package dialog N 4 Switch back to the Map module 5 Inthe Feature Object gt MODFLOW MODPATH command 6 Select OK at the prompt Note At this point our local scale model does not include the wells involved in the pump and treat sy
114. groundwater contamination The results of this simulation will be used as the flow field for 4 2 GMS Tutorials Volume a particle tracking and a transport simulation in the MODPATH tutorial and the MT3DMS tutorial North Limestone Outcropping a 22 we Proposed ae ee Landfill Well 1 Site Well 2 Creek beds 4 1 Site to be Modeled in This Tutorial Plan View of Site b Typical North South Cross Section Through Site We will be modeling the groundwater flow in the valley sediments bounded by the hills to the north and the two converging rivers to the south A typical north south cross section through the site is shown in Figure 4 16 The site is underlain by limestone bedrock which outcrops to the hills at the north end of the site There are two primary sediment layers The upper layer will be modeled as an unconfined layer and the lower layer will be modeled as a confined layer MODFLOW Conceptual Model Approach 4 3 The boundary to the north will be a no flow boundary and the remaining boundary will be a specified head boundary corresponding to the average stage of the rivers We will assume the influx to the system is primarily through recharge due to rainfall There are some creek beds in the area which are sometimes dry but occasionally flow due to influx from the groundwater We will represent these creek beds using drains
115. gt 18 Locate open the directory entitled tutfiles modfmap 19 Select the file entitled start gpr 20 Choose the Open button Now that the image is imported it will appear each time the screen is refreshed All other objects are drawn on top of the image The image only appears in plan view 4 5 Saving the Project Before we make any changes lets save the project under a new name 4 Select the File Save As command 5 Enter easttex as the name of the project 6 Select the Save button Now you can hit the save button j periodically as you develop your model 4 6 Defining the Units At this point we can also define the units used in the conceptual model The units we choose will be applied to edit fields in the GMS interface to remind us of the proper units for each parameter 4 Select the Edit Units command 5 For Length select ft for feet For Time select d for days We will ignore the other units they are not used for flow simulations 6 Select the OK button 4 7 Defining the Boundary The first step is to define the outer boundary of the model We will do this by creating an arc which forms a closed loop around the site MODFLOW Conceptual Model Approach 4 5 4 7 1 Create the Coverage 1 2 Switch to the Map module Right click on the Map Data folder in the Data Tree and select the New Conceptual Model command For the Name enter East Texas For the Model select MODFLOW C
116. hdraw contaminated water migrating from the injection well A steady state flow solution will be computed and a transient transport simulation will be performed over a one year period 6 2 GMS Tutorials Volume Constant head boundary H 250 m flow model No mass flux boundary transport model INJECTION WELL O 0 001 mvs C 57 87 ppm Hyd Cond 1 474x107 m s LOW K ZONE No flow boundary No flow boundary flow model DY 2000 PUMPING WELL flow model No mass flux 00189 ms No mass flux boundary boundary transport model transport model Number of rows 40 Number of columns 32 Aquifer thickness 10 m K 1 474 10 mis Porosity 0 3 Longitudinal dispersivity 20 m Dispersivity ratio 0 2 Simulation time 1 0 yr DX 1600 m Constant head boundary H 36 25 m Figure 6 1 Sample Flow and Transport Problem 6 2 Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state 6 3 Required Modules Interfaces You will need the following components enabled to complete this tutorial e Grid e MODFLOW e MT3DMS You can see if these components are enabled by selecting the File Register command MT3DMS Grid Approach 6 3 6 4 The Flow Model Before setting up the MT3DMS simulation we must first have MODFLOW simu
117. he data for the source sink mixing package However the only data required in this package for our simulation are the concentrations assigned to the recharge from the landfill These values were automatically assigned to the appropriate cells from the conceptual model Thus the input data for this package are complete 7 14 Saving the Simulation We are now finished inputting the MT3DMS data and we are ready to save the model and run the simulation To save the simulation 7 8 GMS Tutorials Volume 1 Select the File Save As command 2 Locate and open the directory entitled tutfiles mt3dmap 3 Enter runl gpr for the file name 4 Select the Save button to save the files 7 15 Running MODFLOW MT3D requires the hff file generated by MODFLOW Since we saved the project in a different folder than the one where we opened the MODFLOW simulation from the hff file does not exist in the new location We need to rerun MODFLOW so that it will recreate the hff file in the current folder To run MODFLOW 1 Select the VODFLOW Run MODFLOW command 2 Select OK at the prompt if it appears 3 When the simulation is finished close the window and return to GMS The solution is imported automatically 7 16 Running MT3DMS Torun MT3DMS 1 Select the MT3D Run MT3DMS command 2 Select Yes at the prompt to save your changes 3 When the simulation is finished close the window and return to GMS The solution is import
118. he menu followed by a symbol followed by the command like this Select the File Open command Values that must be entered by the user are given in bold like this Enter 2 0 for the Hydraulic conductivity CHAPTER 2 MODFLOW Grid Approach Two approaches can be used to construct a MODFLOW simulation in GMS the grid approach and the conceptual model approach The grid approach involves working directly with the 3D grid and applying sources sinks and other model parameters on a cell by cell basis The conceptual model approach involves using the GIS tools in the Map module to develop a conceptual model of the site being modeled The data in the conceptual model are then copied to the grid The grid approach to MODFLOW pre processing is described in this tutorial In most cases the conceptual model approach is more efficient than the grid approach However the grid approach is useful for simple problems or academic exercises where cell by cell editing is necessary It is not necessary to complete this tutorial before beginning the MODFLOW Conceptual Model Approach tutorial 2 1 Description of Problem The problem we will be solving in this tutorial is shown in Figure 2 1 This problem is a modified version of the sample problem described near the end of the MODFLOW Reference Manual Three aquifers will be simulated using three layers in the computational grid The grid covers a square region measuring 75000 ft by 75
119. he particle set and select the Properties command from the pop up menu 5 8 1 5 8 2 MODPATH 5 5 Particle Sets Dialog This brings up the Particle Sets dialog Using the Particle Sets dialog you can change the particle set properties including the tracking direction and the tracking duration One particle set is always designated as the active particle set Whenever new points are created they are added only to the active particle set Similarly you can only delete points from the active particle set By default the tracking duration is set to track to the end meaning MODPATH will track the particles until they run into something a sink the edge of the model etc Let s change the tracking duration to a specific value 1 In the Track column switch the option to Duration in the pull down list 2 In the Duration column change the value to 3 000 3 Click OK You should now see a smaller capture zone for the well Duplicating Particle Sets Lets display a 3000 day capture zone and a 1000 day capture zone We ll turn the arrows off so they don t obscure the display of the capture zones 1 Select the Display Options command 2 Turn off the Direction arrows and click OK Now we will create another particle set by copying the existing one 1 Using the Data Tree change the name of the particle set to 3000 days so that we know it goes for 3000 days 2 Right click on the particle set and sele
120. head arc is assumed to vary linearly along the length of the arc Select the Select Points Nodes tool Double click the node on the west left end of the arc on the southern bottom boundary Enter a constant value of 697 for the Head Stage Select the OK button In a similar fashion assign a value of 685 to the node at the junction of the two rivers and a value of 703 to the node at the top of the arc on the east boundary of the model Defining the Drain Arcs At this point we will enter the arcs at the locations of the creek beds to define the drains Select the Create Arc tool G Create the arc labeled as arc 1 in Figure 4 4 Start by clicking on the bottom arc create the arc by clicking points along the creek bed and end the arc by double clicking on the top arc Notice that when you click in the vicinity of a vertex on an existing arc or on the edge of an arc GMS automatically snaps the arc you are creating to the existing arc and makes a node at the junction of the two arcs MODFLOW Conceptual Model Approach 4 9 3 Create the arcs labeled arc 2 and arc 3 in Figure 4 4 the same way you made arc 1 Figure 44 Drain Arcs Next we will define the arcs as drains and assign the conductance and elevation to the arcs 1 Select the Select Arcs tool 2 Select all of the drain arcs by clicking on the arcs while holding down the Shift key 3 Select Properties button ES 4 Inthe All
121. his model to the grid and compute a new solution using the steps described above 8 15 Conclusion This concludes the Model Calibration tutorial Here are the things that you should have learned in this tutorial e Observation points will display a target next to them that shows how well the computed values match the observed values Model Calibration 8 13 With MODFLOW the computed values at the observation points come from MODFLOW and not GMS Thus if you create an observation point you will have to run MODFLOW before you will see a target If you want to specify a flow observation that applies to a network of streams you can create an arc group A number of different plots are available when doing model calibration Whenever you make changes to the conceptual model you must use the Feature Objects Map gt MODFLOW MODPATH command and save your project before running MODFLOW 9 Automated Parameter Estimation The Model Calibration tutorial describes the basic calibration tools provided in GMS It illustrates how head levels from observation wells and observed flows from streams can be entered into GMS and how these data can be compared to model computed values It also describes how a trial and error method can be used to iteratively adjust model parameters until the model computed values match the field observed values to an acceptable level of agreement In many cases calibration can be achieved much mo
122. ialog Select the Create Arc tool i Click out the river arc starting near the northern specified head boundary and ending near the southern specified head boundary as shown in Figure 3 10 below Don t extend the river beyond the boundary coverage 3 16 GMS Tutorials Volume Ve 278 aw 5 10 11 12 13 14 15 16 Figure 3 10 Modeling the River Select the Select Arcs tool Click anywhere on the river arc to select it Select Properties button Change the type of the arc to river Enter a value of 5000 0 for the Cond conductance and click OK Select the Select Points Nodes tool Double click on the river node at the northern end of the model Enter 182 0 for the Head and 179 0 for the Elev Select OK to exit the dialog Repeat the same process for the southern river node and enter 178 6 for the Head and 175 6 for the Elev 3 14 Running MODAEM We are now ready to run MODAEM again MODAEM 3 17 1 Hit the F5 key 2 When MODAEM is finished select the Close button You should notice some change in the head contours particularly around the river arc 3 15 Adding Recharge Now we will add recharge to the model 1 Right click on the Boundary coverage and select the Duplicate command 2 Double click on the Copy of Boundary coverage 3 Change the name to Recharge 4 In the Sources Sinks BCs section of the dialog toggle off Specified Head an
123. ic conductivity Pilot points can be thought of as a 2D scatter point set Instead of creating a zone and having the inverse model estimate one value for the entire zone the value of the parameter within the zone is interpolated from the pilot points Then the inverse model estimates the values at the pilot points Figure 9 3 shows a set of pilot points used to estimate horizontal hydraulic conductivity Notice how the hydraulic conductivity now varies from cell to cell When the inverse model runs the values at the pilot points are adjusted and the surface defining the variation of K values is warped until the objective function is minimized 9 10 GMS Tutorials Volume Figure 9 3 Pilot Points and Resulting Conductivity Field The pilot point method can be used with both the MODFLOW 2000 PES process and PEST However PEST provides an additional option for the pilot point method called regularization Regularization imposes an additional measure of stiffness to the parameter being interpolated via a homogeneity constraint In the absence of any strong influence from the PEST objective function this constraint causes values at pilot points to approximate the mean value of adjacent pilot points This constraint makes the inversion process much more stable and makes it possible to violate one of the typical constraints associated with parameter estimation namely the requirement that the number of p
124. in the Data Tree and select the New Coverage option Change the name of the coverage to Observation Under the Observation Points section toggle on the Head option Select OK to exit the dialog Select the Open button 2 Locate and open the directory entitled tutfiles modaem Select and open the file well_head txt Toggle on the Heading row toggle MODAEM 3 19 Click the Next gt button Change the GMS data type to Observation data In the File preview section of the dialog change the Type of the first column to Name the second to X the third to Y and the fourth to Obs Head Select the Finish button to exit the dialog 3 19 Running MODAEM We are now ready to run MODAEM again 1 2 Hit the 5 key When MODAEM is finished select the Close button You should now see observation targets appear 3 20 Conclusion This concludes MODAEM tutorial Here are the things that you should have learned in this tutorial MODAEM is an analytic element model located in the Map module of GMS and it uses only points arcs and polygons only to compute solutions Images that do not come with registration information can be registered in GMS so that they are displayed in the appropriate location in your model coordinate system The Map module is used to construct conceptual models using feature objects points arcs and polygons Feature objects are grouped into coverages There is always only one activ
125. ing simulated This model is used to make predictions With a stochastic approach a set of models is constructed where each model in the set is thought to be equally probable Each model is then used to make the prediction or simulate a given scenario and the results are used to estimate a probability or risk that a certain outcome will occur While this approach still relies on underlying model assumptions to generate initial parameter estimates it more honestly reflects the uncertainty associated with modeling GMS includes two basic methods for generating stochastic simulations parameter randomization and indicator simulations With the parameter randomization method selected model parameters are randomized using either a Random Sampling or Latin Hypercube approach Each combination of input parameters defines a model instance With the indicator simulation approach 12 2 12 1 GMS Tutorials Volume multiple equally probable realizations of the aquifer heterogeneity are generated and each realization is used to define a model instance This tutorial illustrates how to develop a stochastic simulation using parameter randomization Parameter randomization utilizes many of the tools described in the Automated Parameter Estimation tutorial Therefore we recommend that you complete that tutorial prior to beginning this one Description of Problem The model we will be using in this tutorial is the same model featured in the MODFL
126. ion and the display order e There are a number of different display options available for pathlines including displaying arrows coloring by zone code and displaying filled polygons representing capture zones in plan view only CHAPTER 6 MT3DMS Grid Approach This tutorial describes how to perform an MT3DMS simulation within GMS An MT3DMS model can be constructed in GMS using one of two approaches the conceptual model approach or the grid approach With the conceptual model approach the sources sinks and zones in the model are defined with GIS objects and automatically assigned to the grid With the grid approach values are manually assigned to the grid While the conceptual model approach is generally preferable for large complicated models simple models can be easily constructed using the grid approach The grid approach is described in this tutorial 6 1 Description of Problem The problem to be solved in this tutorial is shown in Figure 6 1 This problem corresponds to the sixth sample problem Two Dimensional Transport in a Heterogeneous Aquifer described in the MT3DMS documentation The problem consists of a low K zone inside a larger zone The sides of the region are no flow boundaries The top and bottom are constant head boundaries that cause the flow to move from the top to the bottom of the region An injection well with a specified concentration provides the source of the contaminants A pumping well serves to wit
127. ion from a steady state simulation to transient 1 Switch to the 3D Grid module 2 Select the VODFLOW Global Options command 3 Select the Transient option 11 8 GMS Tutorials Volume 11 7 2 Setting up the Stress Periods Now we will set up the stress period information for MODFLOW 1 Select the Stress Periods button 2 Turn on the Use dates times option When the Use dates times option is used all input fields in the MODFLOW interface in the 3D Grid module expect the date time format for input The date time format is used to display time values such as the time step values when post processing If the option is not used scalar time values e g 100 120 etc are displayed 3 Change the Number of stress periods to 7 We want the stress periods to match the times where our input data in the map module changes For example the value for recharge changes at three different dates 1 1 1986 3 1 1986 and 7 1 1986 Therefore we need to make sure that we have stress periods that start at those times and at the time corresponding to changes in the pumping schedules 4 Enter the following times and time steps for the stress periods Start Num time steps 10 1 1985 12 00 00 AM 1 1 1986 12 00 00 AM 3 1 1986 12 00 00 AM 5 1 1986 12 00 00 AM 6 1 1986 12 00 00 AM 7 1 1986 12 00 00 AM 9 1 1986 12 00 00 AM d 12 1 1986 12 00 00 AM Co CoO gt
128. iple equally probable realizations of the aquifer stratigraphy are generated These realizations represent different distributions of material indicator zones within the aquifer A set of aquifer properties is associated with the materials and the model is run once for each of the N realizations In GMS the multiple realizations of the aquifer heterogeneity are typically generated using the T PROGS software T PROGS can be used to generate two types of output multiple material sets arrays of material ids or multiple MODFLOW HUF input sets In each case GMS can launch MODFLOW in batch mode and generate a flow solution for each model instance For this tutorial we will be using a pre defined set of material sets generated by T PROGS The steps involved in running a T PROGS simulation are described in 7 PROGS tutorial 13 1 Description of Problem The model for this tutorial is based on the Longhorn Army Ammunition Production LHAAP site in Texas used in the TPROGS tutorial While we will be using the same site boundaries the grid used in this simulation will have only one layer to facilitate a shorter run time We will use a pre defined T PROGS simulation containing 30 material sets The material sets will be 13 2 GMS Tutorials Volume used with the stresses and boundary conditions depicted in Figure 13 1 There is a small drinking water well on the right side of the model This well averages 25 ft d The regional grou
129. kage The Recharge package is used to simulate recharge to an aquifer due to rainfall and infiltration To enter the recharge data 1 Select the MODFLOW Source Sink Packages submenu and the Recharge Package command 2 Select the Constant Array button 3 Enter a value of 0 003 and click OK 4 Select the OK button to exit the Recharge Package dialog 2 10 The Drain Package We will now define the row of drains in the top layer of the model To define the drains we must first select the cells where the drains are located and then select the Point Sources Sinks command 2 10 1 Selecting the Cells The drains are located in the top layer layer 1 Since this is the current layer we don t need to change the view We need to select the cells on columns 2 10 of row 8 To select the cells 1 Choose the Select Cells tool Ae 2 Select the cell at i 8 j 2 2 17 GMS Tutorials Volume 3 Notice that as you move the cursor across the grid the ijk indices of the cell beneath the cursor are displayed in the Edit Window at the bottom of the screen 4 Hold down the Shift key to invoke the multi select mode and select the cells on columns 3 10 of the same row as the cell you have already selected Figure 2 2 Figure 2 2 Cells to be Selected 2 10 2 Assigning the Drains To assign drains to the cells 1 Select the MODFLOW Sources Sinks command 2 Select the Drain tab
130. l Before editing the hydraulic conductivity values we will first make the hydraulic conductivity zone coverage the active coverage 4 N 1 Switch to the Map module 2 Inthe Data Tree select the Hydraulic Conductivity coverage To edit the hydraulic conductivity values 1 Select the Select Polygons tool 2 While holding the Shift key select polygons 1 and 2 shown in Figure 8 4 3 Select the Properties button ey 4 Enter a value of 2 for the Horizontal K for each polygon 5 Select the OK button 6 Double click on polygon 3 shown in Figure 8 4 7 Enter a value of 0 5 for the Horizontal 8 Select the OK button 8 10 GMS Tutorials Volume 9 Click outside the model to unselect the polygon Figure 8 4 Polygons to be Selected 8 11 Converting the Model Now that the values have been edited the next step is to convert the conceptual model to the grid based numerical model 1 Select the Feature Objects Map gt MODFLOW MODPATH command from 2 At the prompt make sure the All applicable coverages option is selected and select OK 8 12 Computing a Solution The next step is to save the MODFLOW model with the new values and compute a new solution 8 12 1 Saving the Simulation To save the simulation 1 Select the File Save As command 2 Enter run3 gpr for the file name and click Save Model Calibration 8 11 8 12 2 Running MODFLOW To run MODFLOW 1 Switch to the 3D Grid modu
131. lation The MODFLOW solution will be used as the flow field for the transport simulation In the interest of time we will read in a previously created MODFLOW simulation 1 Select the Open button gt 2 Locate and open the directory entitled tutfiles mt3dgrid 3 Change the Files of type selection to Model Super Files 4 Select the file entitled flowmod mfs 5 Choose the Open button Now we ll save our project under a new name Since we re changing the name we will run MODFLOW to compute solution files with the new name Otherwise when MT3D runs it will look for solution files with the new name and not find any 6 Select the File Save As command 7 Locate and open the directory entitled tutfiles mt3dgrid 8 Change the file name to transport gpr and click Save 9 Switch to the 3D Grid module 10 From the MODFLOW menu select the Run MODFLOW command 11 When it finishes running select the Close button 6 5 Building the Transport Model 6 5 1 Now that we have a flow solution we are ready to set up the MT3DMS transport simulation Like MODFLOW MT3DMS is structured in a modular fashion and uses a series of packages as input Consequently the GMS interface to MT3DMS is similar to the interface to MODFLOW and we will follow a similar sequence of steps to enter the input data Initializing the Simulation First we will initialize the MT3DMS simulation 1 Select the MT3D New Simulation command 6 4 G
132. lding the Polygon Next 1 we will use the arcs to build a polygon defining the model domain Select the Feature Objects Build Polygons command 10 7 4 Marking the Specified Head Arcs The next step is to mark the specified head boundaries 1 2 5 6 Select the Select Arcs tool While holding the Shift key select the arcs on the left and right sides of the model Select Properties button In the row of the spreadsheet change the type to spec head This will make both arcs specified head arcs Change the layer assignment so that it goes from 1 to 2 Select the OK button At this point we need to select the nodes of the specified head arcs and assign a head value Regional to Local Model Conversion 10 7 1 Select the Select Points Nodes tool 2 Select the two nodes the left side of the model 3 Select Properties button eS 4 Inthe Head Stage field enter a head value of 1050 for both nodes and hit the OK button 5 Repeat this process for the two nodes on the right side of the model but assign a head value of 1100 10 8 Creating the Local MODFLOW Model We are now ready to convert the conceptual model to a grid model First we will create a new grid frame that fits the local model 1 Select the Feature Objects Grid Frame command 2 Select the OK at the prompt 3 If desired you can use grid frame tool to position the grid frame to better match the local
133. le 2 Select the VODFLOW Run MODFLOW command 3 Select OK at the prompt 4 When the MODFLOW simulation is completed select the Close button The solution is read in automatically Note that the plots in the Plot Window have been updated Up to this point we have not paid much attention to our flow target on the arc group In the next section we will create a plot that shows how well the flow target is being met Note that although the error improved for the observation wells the head is still too low on the left and right sides of the model 8 13 Error vs Simulation Plot When performing trial and error calibration it is important to keep track of the trend in the error as new solutions are repeatedly computed GMS provides a special calibration plot to simplify this task 1 Select the Plot Wizard button ll 2 Select the Error vs Simulation plot 3 Select the Next button 4 Select the Finish button The change in each of the three error norms from one solution to the next is clearly visible in the new plot The plot is updated as each new solution is read in Ideally as you make changes to the model the error should gradually become smaller and smaller If a bad choice is made in changing the model the error may temporarily increase In most cases it is a good idea to keep a log of the changes made and the resulting errors 8 14 Continuing the Trial and Error Calibration At this point you are free to continue o
134. lick OK Right click on the East Texas conceptual model and select the New Coverage command from the pop up menu Change the Coverage name to Boundary Change the Default elevation to 700 Change the Default layer range to go from 1 to 2 Click OK 4 7 2 Create the Arc 1 2 4 Select the Create Arc tool Begin the arc by clicking once on the left west side of the model at the location shown in Figure 4 2 Create the arc by proceeding around the boundary of the site in a counter clockwise direction and clicking on a sequence of points around the boundary Don t worry about the spacing or the exact location of the points just use enough points to define the approximate location of the boundary The boundary on the south and east sides of the model should coincide with the rivers The boundary along the top should coincide to the limestone outcropping as shown in Figure 4 2 To end the arc double click on the point where you began Note As you are clicking on the points if you make a mistake and wish to back up a point or two press the Backspace key If you wish to abort the arc and start over press the ESC key 4 6 GMS Tutorials Volume 70 Click points along limestone outcropping 2 5 Double click Click points along this river Figure 4 2 Creating the Boundary Arc 4 8 Building the Local Sourc
135. low boundary along the top and the other two arcs will define the two rivers An arc is split by selecting one or more vertices on the arc and converting the vertices to nodes 1 Select the Select Vertices tool 2 Select the two vertices shown in Figure 4 3 Vertex 1 is located at the junction of the two rivers Vertex 2 is located at the top of the river on the east side of the model To select both vertices at once select the first vertex and then hold down the Shift key while selecting the other vertex 3 Select the Feature Objects Vertices lt gt Nodes command Figure 43 Convert Vertices to Nodes Now that we have defined the three arcs we will specify the two arcs on the rivers as specified head arcs 1 Select the Select Arcs tool 4 8 GMS Tutorials Volume 4 8 2 5 6 Select the arcs on the south and east and right and bottom sides of the model by selecting one arc and holding down the Shift key while selecting the other arc Select Properties button eS Find the spreadsheet cell corresponding to the Al row and the column In this cell select the spec head type This will change the types for both arcs Select the OK button Click anywhere on the model other than on the arcs to unselect them Note that the color of the arcs has changed indicating the type of the arc The next step is to define the head at the nodes at the ends of the arcs The head along a specified
136. n 1 Select the File Save As command 2 Enter run2 gpr for the file name 3 Select the Save button 7 22 Running MT3DMS To run MT3DMS 1 Select the MT3D Run MT3DMS command 2 When the simulation is finished close the window and return to GMS The solution is imported automatically 7 17 GMS Tutorials Volume 7 23 Viewing the Solution After the simulation finishes and the solution is read 1 In the Time Step list below the Data Tree select the last time step Notice that at the end of the simulation the plume is smaller and less advanced than in the first simulation 7 24 Generating a Time History Plot A useful way to compare two transient solutions is to create an observation point and generate a time history plot The fastest way to do this is to create an Active Data Set Time Series plot 7 24 1 Creating a Time Series Plot 1 Select the Plot Wizard button 2 Select the Active Data Set Time Series option for the plot type 3 Select the Finish button 4 Select a cell in the grid near the landfill Notice that the plot shows the concentration v time 5 Select a different cell and notice that the plot updates If no cell is selected then the plot will not show any data If you want to take the plot data and put it into Excel you can right click on the plot and select the view values option This brings up a spreadsheet that you can copy and then paste into Excel 7 25 Conclusion
137. n data in the Chemical Reactions Package dialog 1 2 Select the MT3D Chemical Reaction Package command In the Sorption section select the Linear isotherm option In the Kinetic rate reaction section select the First order irreversible kinetic reaction option In the lower part of the dialog enter the following values Bulk density 104 1st sorption constant 0 003 Rate constant dissolved phase 0 0001 Rate constant sorbed phase 0 0001 Switch the layer to layer 2 and enter the following values MT3DMS Conceptual Model Approach 7 11 Bulk density 100 1st sorption constant 0 003 0 00005 Rate constant dissolved phase Rate constant sorbed phase 0 00005 6 Select the OK button to exit the dialog 7 20 Run Options We are about ready to save the project under a new file name However we will face the same problem we did earlier with the hff file That is MT3D will look for a hff file with the same name as the we are about to use to save the project That file doesn t exist We could rerun MODFLOW to create it but there s another way 1 Select the MT3D Run Options command 2 Select the Single run with selected MODFLOW solution option Make sure that ruant MODFLOW is the selected solution 3 Select OK With this option GMS tells MT3D to use the hff file we generated previously 7 21 Saving the Simulation We are now ready to save the new simulatio
138. n your own with the trial and error calibration process using the steps outlined above You may wish to change both the recharge and the hydraulic conductivity values Before you edit the 8 12 GMS Tutorials Volume recharge values be sure to make the coverage visible by selecting it in the Data Tree 8 14 1 Changing Values vs Changing Zones For this tutorial you should be able to get a good match between the computed and observed values simply by changing the hydraulic conductivity and recharge values assigned to the polygonal zones In a real application however you may also need to change the size and distribution of the zones in addition to the values assigned to the zones 8 14 2 Viewing the Answer If you wish to view the answer a map file can be imported which contains a set of parameter values which result in a solution that satisfies the calibration target for each of the ten observation wells Before reading in the new conceptual model you must first delete each of the three MODFLOW coverages 1 Switch to the Map module 2 In the Data Tree highlight and delete each of the three MODFLOW coverages Sources amp Sinks Recharge and Hydraulic Conductivity To read in the new conceptual model 1 Select the Open button gt 2 Select No at the prompt to confirm we don t want to save our changes if it appears 3 Select the file titled answer map 4 Select the Open button You can now convert t
139. nd select OK at the prompt 7 10 Layer Thicknesses To define the aquifer geometry MT3DMS requires an HTOP array defining the top elevations of the uppermost aquifer A thickness array must then be entered for each layer Since we defined the layer geometry in the MODFLOW model no further input is necessary MT3DMS Conceptual Model Approach 7 7 7 11 The Advection Package Before running MT3D there are a few more options to enter First we need to select a solver for the Advection package We want to use the Third Order TVD scheme ULTIMATE solution scheme This is the default so we don t need to do anything 7 12 The Dispersion Package Next we will enter the data for the Dispersion package 1 2 Switch to the 3D Grid module 8 Select MT3D Dispersion Package command The longitudinal dispersivity values were automatically assigned from the conceptual model All we need to do is specify the remaining three parameters 2 Enter a value of 0 2 for the Ratio of transverse dispersivity to longitudinal dispersivity parameter Enter a value of 0 2 for the Ratio of vertical dispersivity to longitudinal dispersivity parameter Ensure that the value of the Effective molecular diff coefficient is 0 Change the Layer to 2 Once again enter 0 2 for both dispersivity ratios Select the OK button to exit the Dispersion Package dialog 7 13 The Source Sink Mixing Package Dialog Finally we must define t
140. nd water flow is from left to right We will use specified head boundaries at the left and right edges of the model at 180 ft and 170 ft respectively H 170 ft Regional Ground Water Flow Direction Extraction Well H 180 ft Boundary of Local Scale Model Figure 13 1 Conceptual Representation of Site to be Modeled Once the model is set up we will run MODFLOW in stochastic mode to generate 30 solutions We will then run the Risk Analysis Wizard to generate a data set representing probability of capture by the extraction well We will contour this data set to illustrate capture zone boundaries for different probabilities of capture 13 2 Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state Stochastic Modeling Indicator Simulations 13 3 13 3 Required Modules Interfaces You will need the following components enabled to complete this tutorial Grid Map MODFLOW Stochastic Modeling You can see if these components are enabled by selecting the File Register command 13 4 Reading in the Project First we will read in a project containing the MODFLOW model and the material sets generated by T PROGS 1 Select the Open button gt 2 Locate and open the tutfiles stochastic2 directory 3 Select the file entitled Ihaap gpr 4 Sele
141. ne code option in the Capture Zones section 3 Turn on the Poly fill option 4 Select the OK button You should now see the capture zone for the landfill pathlines Notice that the capture zone includes areas where there are no pathlines To fix this 1 Select the Display Options command 2 Change the Thin triangle ratio to 0 85 and select the OK button Notice how the boundary of the capture zone has been sucked in so that it corresponds more closely to the pathlines This is what the Thin triangle ratio does If you decrease it too much the capture zone will begin to look bad The default was appropriate for the well capture zone we saw earlier but not for the landfill capture zone You will sometimes have to adjust this value to get a good looking capture zone 5 13 Conclusion This concludes the MODPATH tutorial Here are the things that you should have learned in this tutorial e MODPATH is available whenever a MODFLOW model is in memory MODPATH requires a flow solution before pathlines can be computed e Unlike most models in GMS MODPATH is much more automated and GMS runs MODPATH behind the scene as soon as starting locations are created e You can create particle starting locations in two ways using either the Generate Particles at Wells or Generate Particles at Selected Cells commands e Particles are grouped into particle sets You use particle sets to control the tracking direction the durat
142. ng the Recharge Zones 4 9 1 4 9 2 The next step in constructing the conceptual model is to construct the coverage which defines the recharge zones We will assume that the recharge over the area being modeled is uniform except for the landfill The recharge in the area of the landfill will be reduced due to the landfill liner system Copying the Boundary We ll create our recharge coverage by copying the boundary 1 Right click on the Boundary coverage and select the Duplicate command from the pop up menu Change the name of the new coverage to Recharge 2 Right click on the Recharge coverage and select the Coverage Setup command 3 In the Areal Properties list turn on the Recharge rate property 4 Select the OK button Creating the Landfill Boundary Next we will create the arc delineating the boundary of the landfill To do this we will first create a closed loop in the form of a rectangle at the approximate location of the landfill We will then edit the nodes and vertices so that the arc coincides precisely with the boundary of the landfill 1 Select the Create Arc tool L 2 Create a rectangular polygon representing the landfill as shown in Figure 4 6 Don t worry about getting the exact coordinates at this point Now that the arc is created in the approximate location we will edit the coordinates of the vertices and nodes to define the precise coordinates 3 Select the Select Vertices tool MODF
143. nhanced for use with GMS This chapter introduces MODAEM to the new user and illustrates the use of GMS for analytic element modeling 3 1 A Short Introduction to the Analytic Element Method This section introduces new modelers to the analytic element method AEM The AEM allows modelers to rapidly model groundwater flow problems using a conceptual modeling toolkit like GMS MODAEM and GMS provide an efficient facility for a variety of modeling situations for example e Simple site scale problems using uniform flow and a few wells e Regional modeling problems that cover very large regions e Screening models that test conceptual models as a preparatory step in the development of more complex numerical models Although MODAEM is currently limited to steady state models of a single aquifer it provides many powerful facilities for regional and local scale modeling This introduction is intended for users who are new to the AEM For a more detailed introduction to the AEM see Analytic Element Modeling of Groundwater Flow Haitjema 1995 for a detailed explanation of the mathematics of the AEM see Groundwater Mechanics Strack 1989 A note to experienced AEM users MODAEM in GMS differs from most analytic element codes e g SLAEM WhAEM for DOS Windows GFLOW TimSL TimML in that the data input 3 2 GMS Tutorials Volume is consistent with MODFLOW This allows the GMS map coverages to be compatible with both
144. ntains an initial estimate of hydraulic conductivities and recharge solution computed with this initial model will then be imported and the error in the initial solution will be analyzed New values for hydraulic conductivity and or recharge will then be entered a new solution will be generated and a new error estimate will be computed These steps will be repeated until the error is reasonably small Model Calibration 8 3 Recharge Zones Hydraulic Conductivity Zones Figure 8 2 Recharge and Hydraulic Conductivity Zones 8 2 Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state 8 3 Required Modules Interfaces You will need the following components enabled to complete this tutorial e e Map e MODFLOW You can see if these components are enabled by selecting the File Register command 8 4 Reading in the Model First we will read in the model 1 Select the Open button ar 2 Locate and open the tutfiles calib directory 3 Select the file entitled bigval gpr 8 4 GMS Tutorials Volume 4 Select the Open button You should see both a grid and a conceptual model appear The conceptual model consists of three coverages The currently active coverage contains the model boundary the specified head boundary the stream and the wells There is also
145. o save your work periodically anyway so let s do so now 1 Select the File Save As command 2 Enter brazil as the name of the project 3 Select the Save button Now you can hit the save button periodically as you develop your model 3 12 Running MODAEM We are now ready to run MODAEM This can be done by selecting the menu command MODAEM Solve or by hitting the F5 key Once this command is executed a dialog will appear showing the output from the MODAEM model 1 2 MODAEM _ 3 15 Hit the F5 key When MODAEM is finished select the Close button Head contours should now appear inside our boundary coverage 3 4 5 9 Select the Display Options button a Select the tab Click on the Options button next to the Contours toggle Change the Contour method to Linear and Color Fill Under the Line options section change the Line style so that the line color is black Under the Fill options section of the dialog change the Transparency value to 0 4 Select the Color Ramp button 10 Under the Palette Method section of the dialog turn on Legend 11 Select OK repeatedly to close all of the dialogs 3 13 Creating the River Now we will add the river to our model 1 Right click on Indiana in the Data Tree and select the New Coverage option Change the name of the coverage to River Under the Source Sink BCs section toggle on the River option Select OK to exit the d
146. odel we will be using in this tutorial is the same model used in the Model Calibration tutorial We will use the computed heads from the steady state calibrated flow model as the starting heads for our transient simulation Transient recharge and pumping conditions will be modeled The recharge rates will be manually entered but the pumping rates will be imported from a text file We will also import a set of transient field observed heads from observation wells 11 2 GMS Tutorials Volume II 11 2 Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state 11 3 Required Modules Interfaces You will need the following components enabled to complete this tutorial e e Map e MODFLOW You can see if these components are enabled by selecting the File Register command 11 4 Reading in the Project First we will read in the project 1 Select the Open button gt 2 Locate and open tutfiles trans directory 3 Select the file entitled start gpr 4 Select the Open button You should see a MODFLOW model with a solution and a set of GIS coverages Two of the coverages are the source sink and hydraulic conductivity coverages used to define the conceptual model The active coverage is the recharge coverage 11 5 Transient Data Strategy When entering the time values as
147. of answers Some of the solutions may indicate flooded cells This means that the computed water table elevation is above the ground surface Note that once an individual solution folder is selected in the Data Tree you can use the up and down arrows on your keyboard to cycle through the solutions 12 12 MT3DMS Now we will run an MT3DMS model using the results from each MODFLOW solution generated by the stochastic flow simulation The MT3DMS model consists of one species leachate from the landfill entering the model from mass flux in the recharge and traveling toward the river and nearby well We will assign a concentration to the recharge coming from the landfill polygon Because the recharge for the landfill area in the MODFLOW model was varied Stochastic Modeling Parameter Randomization 12 9 as a parameter the mass flux recharge rate X concentration of contaminant leaving the landfill will vary for each model run We will then read in the computed transport solutions and perform probabilistic threshold concentration analysis 12 13 Reading in the MT3DMS Project First we will read in the MT3DMS project 1 Select the File Save command This will save the project in its current state including the stochastic solutions 2 Select the Open button a 3 Locate and open the tutfiles stochastic1 directory 4 Change the Files of type to Model Super Files 5 Select the file entitled leachate mts 6 Select the Open
148. ol Next we will specify the output options 1 Select the Output Control button 2 Select the Print or save at specified interval option 3 Change the specified interval to 10 This will output a solution at every tenth transport step 4 Select the OK button to exit the Output Control dialog ICBUND Array The ICBUND array is similar to the IBOUND array MODFLOW ICBUND array is used to designate active transport cells ICBUND gt 0 inactive transport cells ICBUND 0 and constant concentration cells ICBUND lt 0 In most problems ICBUND will be similar to IBOUND but it will differ Typically the cells which are constant head cells in the flow solution are not constant concentration cells in the transport solution For our problem all of the cells are active therefore no changes are necessary Starting Concentration Array The starting concentration array defines the initial condition for the contaminant concentration In our problem the starting concentrations are all zero and the default is adequate HTOP and Thickness Arrays MT3DMS uses the HTOP array and a thickness array to determine the layer geometry However the values for these arrays are determined by GMS automatically from the MODFLOW layer data and no input is necessary Porosity Array Finally we will define the porosity for the cells Our problem has a constant porosity of 0 3 This is the default value in GMS so no changes need to be made
149. olor Fill 3 Select the Color Ramp button to bring up the Color Ramp Options dialog 4 Make sure the Legend box is checked 5 Select OK on both dialogs to exit You should now see a probability plume extending from the landfill You can cycle through the time steps in the Time Step window below the Tree Window to see the probabilities at the different times 12 17 GMS Tutorials Volume 12 19 Conclusion This concludes the Stochastic Modeling Parameter Randomization tutorial Here are the things that you should have learned in this tutorial GMS supports two types of stochastic approaches parameter randomization and indicator simulations With parameter randomization you can do random sampling latin hypercube sampling or user defined sampling You can run an MT3DMS model against all the stochastic MODFLOW solutions but currently GMS does not support running MT3DMS _ stochastically itself randomizing the MT3DMS parameters You can run the Risk Analysis Wizard on any folder of solutions One of the options in the Risk Analysis Wizard is a threshold analysis CHAPTER 13 Stochastic Modeling Indicator Simulations GMS supports two methods for performing stochastic simulations parameter randomization and indicator simulations The previous tutorial illustrated the parameter randomization approach The indicator simulation approach is described in this tutorial With the indicator simulation approach mult
150. on The model included a proposed landfill For this tutorial we will be performing two transport simulations to analyze the long term potential for migration of leachate from the landfill In the first simulation we will be modeling transport due to advection and dispersion only In the second simulation we will include sorption and decay in addition to advection 7 2 Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state 7 2 GMS Tutorials Volume 7 3 Required Modules Interfaces You will need the following components enabled to complete this tutorial Grid Map MODFLOW MT3DMS You can see if these components are enabled by selecting the File Register command 7 4 Importing the Project The first step is to import the East Texas project This will read in the MODFLOW model and solution and all other files associated with the model To import the project 1 Select the Open button a 2 Locate and open the directory entitled tutfiles modfmap sample 3 Select the file entitled sample gpr 4 Choose the Open button 7 5 Defining the Units First we will define the units We will not change the length and time units these must be consistent with the flow model However we need to define units for mass and concentration 1 Select the Edit Units command 2 S
151. on due to the source of the points Ground surface points are often digitized from a map while layer elevations typically come from borehole data Layer interpolation is covered in depth in the Jnterpolating Layer Data tutorial 4 15 1 Importing the Ground Surface Scatter Points The scatter points have already been read in because they were included in the project file that we read in the beginning These points came from importing a text file as described in the 2D Geostatistics tutorial The scatter sets are hidden so we will unhide them so you can see them 1 Switch to the 2D Scatter Point module 4 18 GMS Tutorials Volume 2 In the Data Tree check the boxes next to the two scatter point sets named terrain and elevs 3 Make the terrain scatter point set the active one by selecting it in the Data Tree A set of scatter point symbols should appear on the model 4 15 2 Interpolating the Heads and Elevations Next we will interpolate the ground surface elevations and starting heads to the MODFLOW grid 1 Select the Interpolation Interpolate gt MODFLOW Layers command in This is the dialog that allows you to tell GMS which data sets you want to interpolate to which MODFLOW arrays The dialog is explained fully in the Interpolating Layer Data tutorial 2 Check to make sure that the ground_elev data set and the Starting Heads array are highlighted and click the Map button 3 Check to make sure that the gr
152. ons tool double click on the polygon 4 Change the Horizonal K to 16 5 Change the Vertical anis to 4 6 Select the OK button 4 10 3 Bottom Layer For the bottom layer 1 Select the Layer 2 coverage in the Data Tree 2 Select the Feature Objects Build Polygons command 3 Double click on the polygon 4 Change the Horizonal K to 32 5 Change the Vertical anis to 4 6 Select the OK button This completes the definition of the coverages in the conceptual model Before continuing to create the grid we will make the sources sinks coverage the active coverage 7 Select the Sources Sinks coverage in the Data Tree 4 11 Locating the Grid Frame Now that the coverages are complete we are ready to create the grid The first step in creating the grid is to define the location and orientation of the grid using the Grid Frame The Grid Frame represents the outline of the It can be positioned on top of our site map graphically 1 Select the Feature Objects New Grid Frame command 4 16 GMS Tutorials Volume 2 Switch to the Select Grid Frame tool and double click on the grid frame 3 For the Z coordinate change the Origin to 550 and the Dimension to 200 This provides a set of initial values for the MODFLOW layer elevation arrays Later we will interpolate the layer elevations 4 Select the OK button to exit the Grid Frame dialog 4 12 Creating the Grid Now that the coverages and the G
153. opriate GMS selects the cells or layers associated with the problem 3 Select the Done button to exit the Model Checker 2 13 Saving the Simulation Now we are ready to save the simulation and run MODFLOW 1 Select the File Save As command 2 Move to the directory titled tutfiles modfgrid 3 Change the file name to gridmod gpr 4 Select the Save button 2 14 Running MODFLOW We are now ready to run MODFLOW 1 Select the VODFLOW Run MODFLOW command MODFLOW Grid Approach 2 15 At this point MODFLOW is launched in a new window The super file name is passed to MODFLOW as a command line argument MODFLOW opens the file and begins the simulation As the simulation proceeds you should see some text output in the window reporting the solution progress 2 When MODFLOW finishes select the Close button 2 15 Viewing the Solution GMS reads the solution in automatically when you close the MODFLOW window At this point you should see a set of head contours for the top layer You may also see some cells containing a blue triangle symbol These cells are flooded meaning the computed water table is above the top of the cell 2 15 1 Changing Layers To view the solution on the middle layer 1 Select the Decrement button in the Mini Grid Plot To view the solution on the bottom layer 2 Select the Decrement button To return to the top layer 3 Select the Increment button twice 2 15 2 Color Fill Contours
154. orials Volume 2 Enter mfsto gpr for the filename 3 Select the Save button 4 Select the MODFLOW Run MODFLOW command MODFLOW is now running in Stochastic mode The spreadsheet at the top shows the set of parameter values associated with each model run The first column indicated whether or not each model run has converged Some combinations of parameter values result in unstable models The lower window shows the text output from MODFLOW Note If you have room on your screen you may wish to resize the output window by dragging the handle in the lower right corner of the window 12 11 Reading in and Viewing the MODFLOW Solutions Once all the MODFLOW runs are completed you can read in the solutions 1 Make sure the Read solution on exit toggle is checked and select the Close button When the MODFLOW dialog closes another dialog appears that lists each MODFLOW solution and whether it converged You now have the option of choosing which of the solutions you want to read in but all converged model solutions are checked by default 2 Select OK to exit the dialog You should see a new folder named mfsto MODFLOW STO appear in the Data Tree You can expand this folder to see the results of the stochastic simulation Clicking on individual solutions within the folder updates the contours on the MODFLOW grid to reflect the solution results You may wish to click on several of the solutions to view the variety in the range
155. orizontal K input field 12 7 3 Mapping the Key Values to the Grid Cells Once the key values are assigned to the polygons they must be mapped to the cells in the MODFLOW grid 1 Select the Feature Objects Map gt MODFLOW MODPATH command 2 Select OK at the prompt 12 8 Selecting the Stochastic Option Before we edit the parameter data we will turn on the Stochastic option This option is located in the Global Options dialog 1 Switch to the 3D Grid module amp 2 Select the VODFLOW Global Options command 3 In the Run options section of the dialog select the Stochastic Simulation option 4 Choose OK to exit the dialog 12 9 Editing the Parameter Data Two options are available when running a stochastic simulation using parameter zones Random Sampling and Latin Hypercube With Random Sampling the total number of runs is specified directly in the Parameters dialog With the Latin Hypercube method the total number of MODFLOW runs is calculated from the number of segments specified for each parameter We are going to use the Latin Hypercube method and we will use three parameters and give each parameter three segments for a total of 27 3 3 3 MODFLOW runs Stochastic Modeling Parameter Randomization 12 7 Now we will create a list of parameters and enter a mean and standard deviation for each parameter that defines a normal probability distribution curve for the parameter value We will also define b
156. ound_elev data set and the Top Elevations Layer 1 array are highlighted and click the Map button 4 Select the OK button to perform the interpolation 4 15 3 Interpolating the Layer Elevations To interpolate the layer elevations 1 Select the elevs scatter point set to make it the active one in the Data Tree 2 Select the Interpolation Interpolate gt MODFLOW Layers command GMS automatically mapped the Bottom Elevations Layer 1 and Bottom Elevations Layer 2 arrays to the appropriate data sets based on the data set name 3 Select the OK button 4 15 4 Adjusting the Display Now that we are finished with the interpolation we can hide the scatter point sets MODFLOW Conceptual Model Approach 4 19 1 Uncheck the scatter point sets in the Data Tree We will also turn off the grid frame 2 Switch to the Map module 3 Select the Display Options button a 4 Turn off the Grid frame option 5 Select the OK button 4 15 5 Viewing the Model Cross Sections To check the interpolation we will view a cross section 1 Switch to the 3D Grid module 2 Select cell somewhere near the center of the model 3 Select the View J Axis button To get a better view of the cross section we will increase the z magnification 1 Select the Display Settings command 2 Enter a value of 5 for the Z magnification factor 3 Select the OK button You may wish to use the arrow buttons in the Tool Palette to vi
157. ounds for the parameters to keep the values within an acceptable range 1 Select the VODFLOW Parameters command This dialog is used to manage the list of parameters and it is explained in detail in the Automated Parameter Estimation tutorial 2 Select the Initialize From Model button Note that all three parameters were automatically found Also note that the parameters have been given a default name The next step is to enter a starting mean minimum and maximum value for each parameter You should notice that the usage fields have been set to stochastic GMS will only perturb the parameters that are labeled as stochastic regardless of the values in the other fields 3 Enter the following data into the parameters spreadsheet Name Mean Value Min Value Max Value HK_300 16 1 100 RCH_200 0 0288 0 01 0 05 RCH_100 0 0003 0 0001 0 0005 4 For the hydraulic conductivity parameter turn on the Log transform option 5 Enter the following values for the standard deviation and number of segments Name Std Deviation Num Segments HK_300 0 5 3 RCH_200 0 01 3 RCH_100 0 001 3 6 Click on the Repopulate Runs button Scroll down in the spread sheet and notice that the parameter values for each run are displayed 7 Select OK to exit the dialog 12 10 Saving the Project and Running MODFLOW We are now ready to save the project and run MODFLOW in Stochastic mode 1 Select the File Save As command 12 8 GMS Tut
158. profile Use the left and right arrow buttons in the mini grid display to move back and forth through the grid You should see a cone of depression at the well When finished 4 Select the View K Axis button 4 22 Viewing the Flow Budget The MODFLOW solution consists of both a head file and a cell by cell flow CCF file GMS can use the CCF file to display flow budget values For example we may want to know if any water exited from the drains This can be accomplished simply by clicking on a drain arc 1 Switch to the Map module 2 Choose the Select Arcs tool I 3 Click on the rightmost drain arc Notice that the total flow through the arc is displayed in the strip at the bottom of the window Next we will view the flow to the river 1 Click on one of the specified head arcs at the bottom and view the flow 2 Hold down the Shift key and select each of the specified head arcs MODFLOW Conceptual Model Approach 4 23 Notice that the total flow is shown for all selected arcs These same steps can be used to display flow through polygons such as recharge polygons Flow for a set of selected cells can be displayed as follows 1 Switch to the 3D Grid module 8 2 Select group of cells by dragging box around the cells 3 Select the Data Flow Budget command This dialog shows a comprehensive flow budget for the selected cells 1 Select Done to exit the dialog 2 Click anywhere outside the
159. project and run MODFLOW in stochastic mode 1 Select the File Save As command 2 Enter matsto gpr for the filename 3 Select the Save button 4 Select the MODFLOW Run MODFLOW command MODFLOW is now running in stochastic mode As each model run finishes the spreadsheet at the top will indicate whether or not the run converged 13 8 Reading in and Viewing the MODFLOW Solutions Once all the MODFLOW runs are completed you can read in the solutions 1 Make sure the Read solution on exit toggle is checked and select the Close button 2 Select OK at the prompt to read in all converged solutions You should see a new folder named matsto MODFLOW STO appear in the Data Tree You may wish to expand this folder and view the individual solutions You will notice that the contours vary greatly depending on the distribution of materials The head loss occurs primarily in the clay zones As you view a particular solution you may wish to select the material set in the Data Tree associated with that solution 13 9 Displaying Pathlines Before performing the probabilistic capture zone analysis we will first view the capture zones corresponding to individual solutions 1 Select the Generate Particles at Wells command 2 Select the OK button to accept the default options You should see a set of pathlines appear As you click on different MODFLOW solutions in the Data Tree the pathlines will be automatically 13
160. re rapidly with an inverse model GMS contains an interface to three inverse models MODFLOW 2000 PES process PEST and UCODE An inverse model is an internal process MODFLOW 2000 PES process or an external utility PEST UCODE that automates the parameter estimation process The inverse model systematically adjusts a user defined set of input parameters until the difference between the computed and observed values is minimized This tutorial illustrates how to calibrate a MODFLOW model using the MODFLOW 2000 PES process and PEST Since this tutorial assumes you understand how to enter field observed values you should complete the previous tutorial Model Calibration prior to beginning this tutorial 9 1 Description of Problem The model we will be calibrating in this tutorial is the same model featured in the Model Calibration tutorial The model includes observed flow data for the stream and observed heads at a set of scattered observation wells The conceptual model for the site consists of a set of recharge and hydraulic conductivity zones These zones will be marked as parameters and an inverse model will be used to find a set of recharge and hydraulic conductivity values 9 2 GMS Tutorials Volume II that minimize the calibration error We will first use the MODFLOW 2000 PES Process and then PEST We will utilize two methods for model parameterization polygonal zones and pilot point interpolation 9 2 Getting Started If you hav
161. rid Frame are created we are now ready to create the grid 1 Select the Feature Objects Map gt 3D Grid command Notice that the grid is dimensioned using the data from the Grid Frame If a Grid Frame does not exist the grid is defaulted to surround the model with approximately 5 overlap on the sides Also note that the number of cells in the x and y dimensions cannot be altered This is because the number of rows and columns and the locations of the cell boundaries will be controlled by the refine point data entered at the wells 2 In the Z Dimension change Number cells to 2 3 Select the OK button 4 13 Defining the Active Inactive Zones Now that the grid is created the next step is to define the active and inactive zones of the model This is accomplished automatically using the information in the local sources sinks coverage 1 Select one of the polygons 2 Select Properties button 3 Confirm that the layer assignment is to 2 and click OK 4 Select the Feature Objects Activate Cells in Coverage s command Each of the cells in the interior of any polygon in the local sources sinks coverage is designated as active and each cell which is outside of all of the polygons is designated as inactive Notice that the cells on the boundary are activated such that the no flow boundary at the top of the model approximately coincides with the outer cell edges of the cells on the perimeter while the MODFLOW Conceptual
162. rid cells and use the MODPATH Porosity command to edit the porosity of the selected cells 5 6 Defining the Starting Locations Now we need to specify the starting locations for the particles We want to create a set of particle starting locations surrounding the cell containing the well on the east right side of the model To generate the starting locations 1 Switch to the 3D Grid module 8 2 Select Generate Particles at Wells command 3 Make sure the number of particles is set to 20 and the Extraction wells option is selected 4 Select the OK button A number of things happen now GMS creates particles at every cell that contains a well It then saves a set of MODPATH input files to a temporary folder and automatically runs MODPATH in the background When MODPATH is done running GMS reads in the pathlines that MODPATH computes This all takes place very quickly usually in a second or two You should now see a set of pathlines that converge on the east well Notice that the pathlines intersect the area covered by the proposed landfill indicating a potential for leachate from the landfill to appear in the water pumped from the well We are not interested in the well on the west left side of the model so we will delete the particles and pathlines for that well 1 Select the Select Starting Locations tool 2 Drag box surrounding the well the west left side of the model 3 Hit
163. rors 4 Select the Done button to exit the Model Checker 4 18 Saving the Project Now we are ready to save the project and run MODFLOW 1 Select the Save button 8 Note Saving the project not only saves the MODFLOW files but it saves all data associated with the project including the feature objects and scatter points 4 19 Running MODFLOW We now ready to MODFLOW 1 Select the MODFLOW Run MODFLOW command At this point MODFLOW is launched and the Model Wrapper appears 2 When the solution is finished select the Close button 4 20 Viewing the Head Contours A set of contours should appear To get better contrast between the contours and the background image we will change the contour color to blue 1 Select the Data Contour Options command 2 Click on the down arrow on the contour Line style button 3 Select a dark blue color 4 Select the OK button to exit the dialog 4 22 GMS Tutorials Volume view the contours for the second layer 1 Select the down arrow in the mini grid display 2 After viewing the contours return to the top layer by selecting the up arrow f 4 21 Viewing the Water Table in Side View Another interesting way to view a solution is in side view 1 Select the Select Cell tool 2 Select a cell somewhere near the well on the right side of the model 3 Select the View J Axis button Notice that the computed head values are used to plot a water table
164. s defines the active region of the grid In most cases all of the polygons will be variable head polygons the default However other polygons may be used For example to model a lake a general head polygon can be used The simplest way to define the polygons is to first create all of the arcs used in the coverage and then select the Build Polygons command This command searches through the arcs and creates a polygon for each of the closed loops defined by the arcs These polygons are variable head by default but may be converted to other types by selecting the polygons and using the Properties command Now that all of the arcs in the coverage have been created we are ready to construct the polygons All of our polygons will be variable head polygons 4 8 4 MODFLOW Conceptual Model Approach 4 11 1 Select the Feature Objects Build Polygons command Even though the polygons are created there is no visible difference in the display You can view the polygons if you wish by selecting the Display Display Options command and turning on the Polygons Fill option Creating the Wells The final step in creating the local sources sinks coverage is to define the wells Wells are defined as point type objects Two wells will be created 1 Select the Create Point tool 2 Move the cursor to the approximate location of Well 1 shown in Figure 4 1 and click once with the mouse to create the point 3 While the new point is selecte
165. selected pathlines 1 Switch to the Select Starting Locations tool 2 Click on one of pathlines that goes from the landfill to the well In the status bar at the bottom of the GMS window you should see some statistics for the selected pathline One of the items is the time We want to know the minimum time We could click on different pathlines one at a time and compare their times but there s an easier way 3 Select all the pathlines that go from the landfill to the well by dragging a box around their starting locations you may need to zoom in to do this In the status bar at the bottom of the GMS window you should see the maximum and minimum lengths and times for all the selected pathlines 5 12 Capture Zones by Zone Code Notice that there is no closed boundary surrounding the pathlines originating from the landfill By default GMS only identifies capture zones for particles originating from wells However capture zones can be associated with particles originating from all cells with the same zone code This feature can be used to group several wells together in the same capture zone For example if there were several wells located close together in a well field you might want to know what the combined capture zone is for all the wells We can also use this feature to show the capture zone for the landfill 1 Select the Display Options command MODPATH 5 9 2 Select the Delineate by zo
166. side the grid Now that all of the wells have been defined we can go back to the top layer 2 Select the Increment button twice in the Mini Grid Plot 2 14 GMS Tutorials Volume 2 12 Checking the Simulation At this point we have completely defined the MODFLOW data and we are ready to run the simulation However before saving the simulation and running MODFLOW we should run the MODFLOW Model Checker and check for errors Because of the significant amount of data required for a MODFLOW simulation it is often easy to omit some of the required data or to define inconsistent or incompatible options and parameters Such errors will either cause MODFLOW to crash or to generate an erroneous solution The purpose of the Model Checker is to analyze the input data currently defined for a MODFLOW simulation and report any obvious errors or potential problems Running the Model Checker successfully does not guarantee that a solution will be correct It simply serves as an initial check on the input data and can save a considerable amount of time that would otherwise be lost tracking down input errors To run the Model Checker 1 Select the VODFLOW Check Simulation command 2 Select the Run Check button A list of messages are shown for each of the MODFLOW input packages If you have done everything correctly there should be no errors for any of the packages When there is an error if you select or highlight the error when appr
167. sink coverage 6 7 Regional to Local Model Conversion 10 5 Expand the Local Model item in the Data Tree by clicking on the plus symbol next to the item Right click on the Copy of ss coverage and select the Delete command from the menu Right click on Local Model item in the Data Tree and select the New Coverage command Change the name of the coverage to local ss In the Sources Sinks BCs spread sheet toggle on Specified Head Change the Default layer range to be 1 to 2 Select the OK button Note that we did not delete the recharge and hydraulic conductivity coverages We will use these coverages to construct our local model The boundaries of the coverages are larger than they need to be but that does not matter 10 7 2 Creating the Boundary Arcs Next we will create the boundary arcs First we need to zoom in on the local site model 1 Select the Zoom tool 2 Drag around the local site boundary the red rectangle Select the local ss coverage in the Data Tree to make it the active coverage Create the boundaries as follows Select the Create Arc tool Create four arcs two parallel to the contours and two perpendicular to the contours as shown in Figure 10 2 Double click on the corners to end each arc 10 6 GMS Tutorials Volume Figure 10 2 Arcs to be Created on Boundary of Local Model 10 7 3 Bui
168. sociated with transient data MODFLOW requires that the time be entered as scalar time values relative to a time value of zero at the beginning of the simulation Furthermore the times must be compatible with the time unit selected for the model This approach can be time consuming since transient data must be converted from a date time format to relative time format The strategy used in GMS for managing transient data makes it possible to enter all time values using a simple date time format Transient data are entered in the conceptual model using date time values The time at the beginning of the first MODFLOW stress period is the reference time This represents the date time corresponding to t 0 in the simulation Managing Transient Data 11 3 When the model is converted from the conceptual model to the grid model the time values in the conceptual model are automatically mapped to the appropriate time values corresponding to the MODFLOW stress periods When the MODFLOW model is saved to disk the date time values are converted to the appropriate relative time values In addition to ease of use another advantage of the transient data strategy used in GMS is that both the spatial and temporal components of the conceptual model are defined independently of the discretization used in both the grid spacing and the stress period size The user can change the stress period spacing and regenerate the model from the conceptual model in seconds 11 6
169. splayed in the cells we edited indicating that the cells are constant head cells Checking the Values To ensure that the IBOUND values were entered correctly 1 Select the MODFLOW Global Options command 2 Select the ROUND button 3 Choose the up arrow to the right of the layer field in the upper left corner of the dialog to cycle through the layers Notice that the leftmost column of cells in the top two layers all have a value of 1 Most of the MODFLOW input data can be edited in GMS using either a spreadsheet like dialog such as this or by selecting a set of cells and entering a value directly whichever is most convenient 4 Select the OK button to exit the JBOUND Array dialog 5 Select the OK button to exit the MODFLOW Global Package dialog 2 8 The LPF Package The next step in setting up the model is to enter the data for the Layer Property Flow LPF package The LPF package computes the conductances between each of the grid cells and sets up the finite difference equations for the cell to cell flow To enter the LPF data 2 8 GMS Tutorials Volume 2 8 1 2 8 2 2 8 3 2 8 4 1 Select the VODFLOW LPF Package command Layer Types The options in the Layer Data section of the dialog are used to define the layer type and hydraulic conductivity data for each layer For our problem we have three layers The top layer is unconfined and the bottom two layers are confined The default layer t
170. stem These could be added at a later time 10 9 Interpolating the Layer Data The final step in the conversion process is to interpolate the regional data from the scatter points to the MODFLOW layer arrays 1 Switch to the 2D Scatter Point module 2 Select the Interpolation to MODFLOW Layers command 3 Select the OK button Now that we re done using the scatter points lets turn them off to make it easier to see the grid 4 Uncheck the box in the Data Tree next to the 2D Scatter Data folder Regional to Local Model Conversion 10 9 10 10 Saving and Running the Local Model We are now ready to save the MODFLOW model and run the simulation 1 Switch to the 3D Grid module 2 Select the File Save As command 3 Change the filename to locmod gpr 4 Select the Save button To run MODFLOW 1 Select the VODFLOW Run MODFLOW command 2 Select OK at the prompt 3 When the simulation is finished select the Close button You should see a set of head contours that closely resemble the head contours from the regional model At this point the local flow model is complete and the injection and extraction wells could be added for the pump and treat simulations 10 11 Conclusion This concludes the Regional to Local Model Conversion tutorial Here are the things that you should have learned in this tutorial e The Grid MODFLOW Layers gt 2D Scatter Points command converts your MODFLOW elevation data into scatter points
171. the window and return to GMS The contours should change Use the Time Steps window to cycle through the different time steps of the solution to see how the pumping schedules of the wells affect the computed heads 11 10 GMS Tutorials Volume 11 11 Transient Observation Data Next we will input transient observation data for this simulation Transient observation well data are also entered using the date time format The data can be entered either manually or by importing a text file containing the transient measurements We will use the text file option We will import the observation point locations from a map file and then import the transient observations from a text file 11 11 1 Importing Transient Observation Data First we need to read in the Map file containing the observation wells 1 Select the Open button gt 2 In the Open dialog change the Files of type selection to Map Files map 3 Select the file named obswells map 4 Select the Open button You should see several observation points appear 11 11 2 Transient Observation Data File Now we will import the transient observation data associated with the observation wells The transient observation data file format is almost identical to the pumping ratehas the following format name date time head OBS 05 12 3 1999 18 00 00 238 OBS 05 1 30 2000 7 38 25 834 OBS 06 3 27 2000 18 00 00 878 OBS 06 12 3 1999 18 00 00 OBS 06 12 5 19
172. the error at the point by selecting the point 1 Switch to the Map module 2 Select the Select Points Nodes tool fe 3 Click on the observation point Notice that a set of statistics related to the point is displayed in the Help Bar at the bottom of the GMS screen Model Calibration 8 7 8 7 Reading a Set of Observation Points 8 7 1 8 7 2 Using the steps defined above we could proceed to enter the remaining nine observation points However in the interest of time we will simply read in a previously prepared map file containing all ten points Deleting the Current Coverage Before reading in the observation points we will first delete the current coverage 1 Select Observation Wells coverage in the Data Tree and select the Delete key 2 Select the Delete command Reading in the Points We will now read in a file containing several observation points 1 Select the Open button a 2 Change the Files of Type to map 3 Select the file entitled obswells map 4 Select the Open button 8 8 Entering the Observed Stream Flow Now that the observation points are defined we will enter the observed flow in the stream Observed flows are assigned directly to arcs and polygons in the local source sink coverage of the conceptual model We will assign an observed flow to the river arcs MODFLOW determines the computed flow from the aquifer to the stream This flow value will be compared to the observed flow GM
173. tioned above the IBOUND values can be entered through the IBOUND 2 7 1 2 7 2 Array dialog In some cases it is easier to assign values directly to cells This can be accomplished using the Cell Properties command Before using the command we must first select the cells in the leftmost column of the top two layers Viewing the Left Column To simplify the selection of the cells we will change the display so that we are viewing the leftmost layer 1 Choose the View the J Axis button The grid appears very thin To make things easier we will increase 2 magnification so that the grid appears stretched in the vertical direction 2 Select the Display Settings command 3 Change the Z magnification to 15 4 Select the OK button Selecting the Cells To select the cells 1 Choose the Select Cells tool A 2 Change the column to 1 in the Mini Grid Display and hit the TAB key Notice that we are now viewing column number one the leftmost column MODFLOW Grid Approach 2 7 3 Drag box around all of the cells in the top two layers of the grid 2 7 3 Changing the IBOUND Value 2 7 4 edit the IBOUND value 1 Select the MODFLOW Cell Properties command 2 Change the ROUND option to Spec head 3 Select the OK button to exit the Cell Properties dialog 4 unselect the selected cells click anywhere outside the grid 5 Select the View the K Axis button Notice that a symbol is di
174. toggle is checked and select the Close button The contours currently shown on the 3D grid are the heads from the MODFLOW with the optimum parameter values We will now look at the observation targets in the map module and the error associated with this model run 2 Switch to the Map module 3 Select the Observation Wells coverage Notice that the residual error has been greatly reduced for all monitoring wells 4 Select the Sources amp Sinks coverage from the Data Tree Notice that the observation target located near the top of the stream shows very little residual error 5 Select the Select Arc Group tool 6 Select the arc group by clicking a river arc Notice the edit strip at the bottom of the graphics window the computed and observed flow is reported Next we will look at some global error norms 7 Switch back to the 3D Grid module 8 Right click on the mfpes solution in the Data Tree and select the Properties command This command brings up a spreadsheet showing the residual error computed observed from this model run The spreadsheet shows the error from the head observations the flow observations and the combined weighted observations You may wish to compare the values from this run to the bigval MODFLOW solution Automated Parameter Estimation 9 9 9 Select the Done button to exit the dialog To see more information concerning the model run you can look in the glo file
175. tual model Select OK at the prompt 9 17 2 Editing the Parameters Now we will edit the parameters that we currently have defined for MODFLOW 1 Switch to the 3D Grid module amp 2 Select the MODFLOW Parameters command 3 Select the HK_200 parameter by clicking on the column labeled 200 4 Select the Delete button 5 Repeat this process for the HK_300 and HK_400 parameters 6 Turn on the Pilot Points option for parameter 100 Click on the Options button in the Pilot Point Options column This brings up the interpolation options dialog Here you can select the scatter point set and data set used with your parameter as well as the interpolation scheme 7 The defaults are appropriate in this case so we won t change anything Select the OK button twice to exit the dialogs 9 17 3 Limiting the Number of Parameter Estimation Runs In the interest of time we will limit the number of iterations that PEST does for our problem 1 Select MODFLOW Parameter Estimation command 2 Change the Max of iterations to 10 3 Select OK to exit the dialog 9 14 GMS Tutorials Volume 9 18 Saving the Project and Running PEST We are now ready to save and run PEST 1 Select the File Save As command 2 Enter pest gpr for the file name 3 Select the Save button 4 From MODFLOW Run MODFLOW command PEST is now running This dialog is similar to the one used when MODFLOW is running
176. und elevation is roughly 600 ft 182 9 m and the aquifer is roughly 60 ft 18 3 m thick 3 8 3 3 3 4 GMS Tutorials Volume Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state Required Modules Interfaces 3 5 You will need the following components enabled to complete this tutorial e Map e MODAEM You can see if these components are enabled by selecting the File Register command Feature Objects We are now ready to begin constructing the conceptual model Conceptual models are constructed using feature objects in the Map module Feature objects in GMS have been patterned after Geographic Information Systems GIS objects and include points nodes arcs and polygons Figure 3 5 Points are xy locations that are not attached to an arc Points have unique ids and can be assigned properties Points are typically used to represent wells Arcs are sequences of line segments or edges which are grouped together as a single polyline entity Arcs have unique ids and can be assigned properties Arcs are grouped together to form polygons or are used independently to represent linear features such as rivers The two end points of an arc are called nodes and the intermediate points are called vertices Nodes have unique ids and can be assigned properties
177. vation 4 19 4 16 CONVERTING THE CONCEPTUAL MODEL ccccccesssscecesssececesseececseceecesaececesssececseseeesesaeeecsesaeeseneaaess 4 20 4 17 Mee 4 21 45185 ST Aa ee 4 21 4 19 R NNINGMODFLOW 4 21 4 20 VIEWING THE HEAD CONTOURS 2 102240000 020 4 21 4 21 VIEWING THE WATER TABLE IN SIDE 222 4 420 0000400040 000000000000 4 22 4 22 VIEWING THE FLOW BUDGET i 4 22 4 23 CONCLUSION eee eR ee oe ee ee es 4 23 5 MODPATH suc ccecsciswcsspnescetessenecsnvesescceacesdevsvncessssseostevensdseedseseteceseesshessbase snsecsutedchassuusesdeobcssveoskessescersiesee 5 1 5 1 DESCRIPTION OF PROBLEM E E E S 5 1 5 2 GETTING STARTED tid ac he die ee ee SRA en ed eee 5 2 5 3 REQUIRED MODULES INTERFACES ccssccssscesssecssscesseecseceseecsseceseecsaeceseeecsaeceseeecsaeceseesesaeceeesesaecenees 5 2 5 4 IMPORTING THE PROJECT E EE E A E E TE 5 2 5 5 8
178. viation maximum and minimum GMS supports both normal and uniform distributions The more simulations generated the greater the confidence that all options have been explored The Latin Hypercube method is an attractive alternative to the Monte Carlo method since it allows for a greater degree of confidence with fewer model runs This can be especially useful for complex models that require large amounts of computational time As with the Random Sampling method the user specifies the mean standard deviation minimum and maximum for each parameter For each parameter the user also specifies a number of segments The probability distribution curve for each parameter is then divided up into n Stochastic Modeling Parameter Randomization 12 3 segments of equal probability Figure 12 1 shows a normal distribution for a parameter that has six segments Note that each segment has an equal area not an equal distance between values Frequency Value Figure 12 1 Latin Hypercube Segmentation for a Parameter with a Normal Distribution and Six Segments The idea behind the Latin Hypercube approach is that the parameter space all possible combinations of parameter values should be sampled as completely as possible with a limited number of model runs Once the segments are defined each parameter is then randomized until a value is found that lies within each probability segment The random numbers for each parameter are combined
179. ygon The key value should be a value that is not expected to occur elsewhere in the MODLOW input file A negative value typically works well We will use seven parameter zones consisting of four hydraulic conductivity zones and three recharge zones The number of observations is eleven consisting of ten observation wells and one stream flow value Note that the number of parameters being estimated should always be less than the number of observations Setting up the Hydraulic Conductivity Zones First we will set up the hydraulic conductivity zones The hydraulic conductivity polygons are shown in Figure 9 1 The five polygons will be used to define four parameter zones The key values associated with each of the four zones are shown on the polygons in the figure 9 4 GMS Tutorials Volume Hydraulic Conductivity Zones Figure 9 1 Hydraulic Conductivity Zones and Parameter Key Values To assign the key values to the polygons 1 Ifnecessary switch to the Map module 2 Expand the Flow Model conceptual model by clicking the plus symbol next to it in the Data Tree 3 Switch to the Hydraulic Conductivity coverage by selecting it from the Data Tree 4 Select the Select Polygons tool 5 Double click on each of the polygons shown in Figure 9 1 and assign the appropriate key value to the Horizontal K input field 9 6 2 Setting up the Recharge Zones Next we will set up the recharge zones The recharge polygons are
180. ype in GMS is convertible which means the layer can be confined or unconfined Thus we don t need to change the layer types Layer Parameters The buttons in the Layer Data section of the dialog are for entering the parameters necessary for computing the cell to cell conductances MODFLOW requires a set of parameters for each layer depending on the layer type Top Layer First we will enter the data for the top layer 1 Select the Horizontal Hydraulic Conductivity button 2 Select the Constant PLayer button 3 Enter a value of 50 4 Select the OK button 5 Select the OK button to exit the Horizontal Hydraulic Conductivity dialog 6 Repeat this process to enter a value of 10 for the vertical anisotropy Middle Layer Next we will enter the data for the middle layer 1 Select the up arrow to the right of the layer edit field in the Layer Data section to switch to layer 2 Enter the following values for layer 2 MODFLOW Grid Approach 2 9 Parameter Value Horizontal Hydraulic Conductivity 3 ft d Vertical Anisotropy 5 2 8 5 Bottom Layer Switch to layer 3 and enter the following values Parameter Value Horizontal Hydraulic Conductivity 7 ft d Vertical Anisotropy 5 This completes the data entry for this dialog 1 Select the OK button to exit the MODFLOW LPF Package dialog 2 9 Recharge Package Next we will enter the data for the Recharge pac
181. yze a number of injection extraction well placement scenarios The wells are part of a treatment system that is being designed Fixed _ Oe Head Boundary Fixed Head Boundary Local Site Boundary Figure 10 1 Regional Model The basic goal of the regional to local model conversion process is to create a 2D scatter point set containing the heads and layer data arrays from the regional model create the local model and interpolate the heads and layer data to the local model A 2D scatter point set is used since the MODFLOW arrays should be interpolated on a layer by layer basis using 2D interpolation GMS provides a set of tools that greatly simplify this process The basic steps are as follows 1 Generate the regional model and compute a solution 2 Use the MODFLOW Layers gt 2D Scatter Points command to create the scatter point set with the layer and head data from the regional model 3 Create the 3D grid for the local scale model 4 Interpolate the heads and layer data values from the scatter points to the MODFLOW layer arrays for the local scale model Regional to Local Model Conversion 10 3 Each of these steps will be described in more detail below 10 2 Getting Started If you have not yet done so launch GMS If you have already been using GMS you may wish to select the File New command to ensure the program settings are restored to the default state 10 3 Required Modules Interfaces You

TUTORIALS Volume II GMS version 5.0

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