AqModel, General Aquifer Modeling Program for
Contents
1. oooooccnnnnnoccccnnnooccncnnanacnnonnnarnncnnnnns 17 Example 2 Steady State 1 Recharge Well Abee 19 Example 3 Transient 1 Pumping Well 19 Example 4 Transient 1 Recharge Well 19 Example 5 Steady State 1 Pumping Well and 1 Recharge Well 19 TPS ease cede eect si ree A a eee ee a aun os 21 Acknowledgments oeae ce oaaasaaasanes a R E AT cece A A 21 TEE TE 22 FIGURES APPENDIX A AqModel Data APPENDIX B Modeling Approaches for Hydraulic Control of Groundwater Contamination WellWare AqModel for Windows User s Manual 2 AqModel Version 2 1 for Windows User s Manual DISCLAIMER WellWare and Gerald T O Neill make no representations or warranties with respect to the contents hereof and specifically disclaim any implied warranties of fitness for any particular purpose WellWare and Gerald T O Neill will not be liable for any damages losses or claims consequent to use of this software or the methods described herein Further WellWare and Gerald T O Neill reserve the right to revise this publication and software and to make changes from time to time in the content hereof without obligation to notify any person of such revisions or changes Models are useful tools and it is the responsibility of the user of a model to correctly apply it in a meaningful way Copyright 1990 1993 by Gerald T O Neill All Rights Reserved No part of this manual may be reproduced or transmitted i2. Number of Pumping and or Recharge Wells Storage Coefficient Input 6 for Steady State Number of Observation Wells Direction of Regional Flow in degrees Hydraulic Gradient of Regional Flow We suggest that you first use PREAQM to create a data set for an AqModel simulation Then make edits to this data set using the Windows Notepad or another text editor as required The data file is simple to construct and edit see Figure 1 and APPENDIX A The input data must be in the units and order specified in APPENDIX A If you use a word processor remember to save the data file as TEXT ONLY because AqModel cannot understand word processing control characters It is important to enter data in the units specified by PREAQM because units are converted in the program A supplementary program call UNITS is provided for units conversions compliments of Milovan S Beljin of HydroLink Double click on the UNITS icon to start UNITS The program is user friendly and self explanatory WellWare AqModel for Windows User s Manual 12 Running AqModel Double click on the AqModel icon to run AqModel AqModel will execute and ask you to enter the name of the data file you created by using PREAQM or a word processing program AqModel displays the input data on the computer screen partly shown on the following figure before proceeding with the simulation You can terminate the program by pressing Ctrl C or by selecting Exit from the File menu On
3. 1000 2000 3090 4000 5000 5000 5000 aas amp 8 4000 J 4000 D f d A o 3000 q 3000 o Cc wen gt ea KC 2002 59 2000 e 4 1000 2000 3000 4000 5000 x in Ft Woods Circle WellWare CS CA 95616 916 758 0290 Effective Software for Groundwater Professionals IA UN Head AqModel User s Guide Figure 5 AqModel Examplel Equipotential Surface Plot Equ lpotential Surface Obs Well 2 Obs We a GE 3160 Woods Circle Davis CA 95616 WellWar ache Effective Software for Groundwater Professionals AqModel User s Guide Figure 6 AqModel Examplel Stream Function Contour Plot Contours of Stream Function in gpm 0 10909 2000 3000 4000 5000 50809 5009 4000 b 4000 q 3082 3080 c 2000 A 2000 gt 19000 1999 o Q Q 190909 20080 3000 4000 5000 x In ft 3160 Woods Circle WellWare Davis CA 95616 916 758 0290 Effective Software for Groundwater Professionals Le z 3 E o o gt VE 7 a S o 69 8 A E 0 H 1900 Li X 2 AgModel User s Guide Figure 7 AqModel Examplel Flow Net Flow Net 1000 2000 3000 4000 5000 5000 4000 3000 A 2000 1909 0 1000 2000 3000 4000 5000 x in Ft WellWare Davis CA 95616 916 758 0290 Effective Software for Groundwater Professionals AqModel User s Guide Figure 8 AqModel Examplel No Pumping Flow Net Reg tonal Flown Net 0 1
4. 1989 The same results were obtained for a problem common to AqModel RESSQ and PATH3D A good introductory note on modeling methods for hydraulic control of groundwater pollution is given by O Neill 1990 This paper presents examples from AqModel RessqM a modified version of RESSQ available from WellWare and PATH3D A copy of the paper is included in APPENDIX B AqModel is limited to determination of steady state capture zones in uniform flows To determine the extent of capture at a given time in steady uniform flows use RessqM by WellWare O Neill 1992 For unsteady flows in non homogeneous aquifers use a numerical groundwater flow modeling code eg MODFLOW and a particle tracking code that works in concert with the flow model e g PATH3D An application of numerical groundwater modeling and particle tracking to analyze remedial alternatives at a Superfund site is presented by Zheng et al 1991 WellWare AqModel for Windows User s Manual 10 Well Head Protection AqModel is useful for determining well head protection areas By using AqModel to determine streamlines and capture zones information is provided on critical areas of the aquifer to protect because eventually the well will discharge water from these areas Of course there is more to a well head protection program than determining groundwater flow paths and this manual does not intend to address well head protection strategies Well construction s
5. Line Help is available for the AqModel Windows interface Select Index from the Help menu for a hypertext list of menu commands and procedures for which help is available AQMODELW Unit File Edit View State Window Help laqhodel Version 2 11 for Windows TH Copyright C 1996 1993 by Gerald T O Neill WellWare 3717 Modoc PL Davis CA 95616 Aq odel calculates drawdown equipotentials and istream functions due to multiple pumping and recharge wells in an aquifer with uniform groundwater flow Please Enter Aqhodel Data File Name EXAMPLE1 DAT Aq odel Example 1 Steady State 1 Pumping Well STEADY STATE SIMULATION Aquifer Parameters Number of Wells Storage Coefficient Direction of Groundwater Flow Gradient of Groundwater Flow Aquifer Transmissivity Aquifer Thickness 1 600E 66 45 00 degrees 2666E 62 5666 66 t 2 day WellWare AqModel for Windows User s Manual 13 While AqModel is executing Running appears in the Status Bar When AqModel is completed Finished appears in the Status Bar Upon normal termination of AqModel the following message box appears AQMODELW O Program Terminated with exit code 0 Exit Window Choose Yes to return to the Program Manager Choose No to return to AqModel if you wish to browse the AqModel window display and or select and copy output to a word processing program Note that AqModel output is automatically saved to a file named AQMODEL TXT ea
6. that of the horizontal If the vertical and horizontal scales were equal the vertical axis would only be about 0 01 inches high Of course the vertical scale is self consistent so one can note the relative differences in head although it is difficult to judge actual elevations on this orthographic projection Figure 6 shows a contour plot of Stream Functions from Example 1 Contours of the stream function are called streamlines and they represent groundwater pathlines in steady state flows This plot shows the paths that groundwater will follow in this example The direction of flow is indicated by the arrows WellWare AqModel for Windows User s Manual 18 AqModel determines the stream function throughout the model area in units of discharge gallons per minute or gpm over the entire aquifer thickness The pumping well discharges at the rate of 200 gpm in this example so if one counts the number of streamlines intersecting the well and multiplies by the contour interval 20 gpm in this case one should get the discharge rate of the well Note that there are in fact 10 streamlines intersecting the well Similarly the discharge between adjacent streamlines along a so called streamtube is obtained by subtracting their values and equals the constant contour interval Note the thick line in the positive X direction at the well how could you miss it This line is the result of a bunching up of contour lines due to the disconti
7. 000 2000 3000 4000 5000 a 50008 4200 4000 30900 e 2000 2000 gt 1008 1000 0 7 Q 12000 2000 30900 4000 5000 x In Ft 3160 Woods Circle Wd sis Effective Software for Groundwater Professionals ft Ln y distance AqModel User s Guide Figure 9 AqModel ExampleS Drawdown Contour Plot Drawdown Contours in ft 6562 4562 2562 562 1438 3438 5438 5438 5438 3438 3438 1438 1438 562 562 2562 2562 4562 4562 6562 6562 6562 4562 2562 b62 1438 23438 5438 x dlstance in ft ER 3160 Woods Circle WellWar Davis CA 95616 916 758 0290 Effective Software for Groundwater Professionals Ft tn y distance AqModel User s Guide Figure 10 AqModel Example5 Equipotential Contour Plot Equtpotentteal Contours in ft 6562 4562 2562 562 1438 3438 5438 5438 3438 1438 562 2562 2562 z 4562 4562 D 6562 8 6562 4562 2562 562 1438 3438 5438 x distance In ft 6562 3160 Woods Circle WellWar 8 Geen CA 95616 916 758 0290 Effective Software for Groundwater Professionals in ft Head 112 AqModel User s Guide Figure 11 AqModel ExampleS Equipotential Surface Plot Equ ipotentlal Surface 3160 Woods Circle Davis CA 95616 WellWar E 916 758 0290 Effective Software for Groundwater Professionals ft tn y distance AgModel User s Guide Figure 12 AqModel Examp
8. 50 ft If we measure the distance from the well to the stagnation point in inches and multiply by 1250 we find the distance to be about 610 ft The width of the capture zone at the well measured along a line perpendicular to the gradient vector is about 1 54 inches or 1925 ft It is also determined by W Q 271 Far upstream from the well the capture zone will be about 3850 ft wide Javandel and Tsang 1986 present useful solutions for dividing streamlines in uniform flow where the wells are aligned perpendicular to the gradient vector Figure 7 shows the flow net from Example 1 obtained by combining the plots of Figures 4 and 6 by double clicking on the Flow Net icon as described in the section Flow Nets WellWare AqModel for Windows User s Manual 19 Figure 8 shows a flow net for Example 1 with no pumping wells The stream function is contoured from 183 65 to 183 65 gpm in 40 gpm intervals The total flow across the diagonal width of the modeled area is Q TiW Darcy s Law 367 3 gpm 183 65 2 Of course you don t need to draw a flow net to determine the discharge across a line perpendicular to the gradient in steady uniform flow But the plot makes it easy to depict the flow Example 2 Steady State 1 Recharge Well This is a steady state problem identical to Example 1 except that the well is now a recharge well AqModel output is listed in EXAMPLE2 TXT Users are encouraged to run the example problem and plot the res
9. AL REAL REAL INTEGER REAL REAL 3 REAL 1 CHARACTER REAL 2 REAL 1 CHARACTER 10 11 All coordinates are absolute in a Cartesian coordinate system with the origin point XMIN YMIN being the lower left corner of the calculation grid All well coordinates real and image must be within the calculation limits defined by XMIN YMIN and XMAX YMAX 1003 Prospect Hts Santa Cruz CA 95065 408 426 8260 WellWare Effective Software for Groundwater Prof VARIABLE TITLE NW IOBS ALPHA GRAD NX AqModel User s Guide Table 2 Description of AqModel Data Input Variables DESCRIPTION A title for the simulation May contain up to 80 alphanumeric characters Total number of pumping and recharge wells in simulation If NW 0 do not enter pumping or recharge well data SKIP LINE 12 A maximum of 501 total wells may be input Aquifer storage coefficient for transient simulations Set S O for steady state simulations If S 0 do not enter TIME SKIP LINE 12 NW Total number of observation wells at which to calculate drawdown Direction of uniform regional groundwater flow in degrees measured counterclockwise from the positive X axis being 0 degrees to a vector in the direction of groundwater flow as shown below 90 Qa 135 00 180 y O 360 270 If ALPHA is negative AqModel will add 360 to the number Therefore to specify flow in a clockwise direction from O degrees as sh
10. AqModel for Windows Version 2 1 User s Manual Drawdown Capture Zones Flow Nets Well Head Protection Well Field Simulation Se d W E d ENN TERS WAR WA E RAS NARS SORA e NY d 211 Uy m My Ki yl My We My S 1 M Y fi Vy Y Ye D Ge YG f Z M Y Z EZ d de Wome Zs d Fa Si 1003 Prospect Hts WellWare sena Cuz CA os Effective Software for Groundwater Prof AqModel for Windows User s Manual 1 AqModel Version 2 1 for Windows User s Manual Contents DISCLAIMER Ai 2 AqModel Requirements cuina dida dd dida 3 SottWware Installation g eegent 3 SURFER iia 3 AqModel Installation eiii ates deeded Glee ed es aires 4 DisK tt PS EE 5 COUNT CS CL Lar A AAA ee 6 Se 7 Drawdown and Potential Distribution ooonnnnnccccnnnooocnnnnnnonannnonanncnonnnnnncnnnnnos 7 Pumping Near Hydrogeologic Boundaries ccooooocccnnnononncnnnonancnnnanancncnnnannnnnnnnns 8 Streami ee a 8 Unconfined A QUISAS A Otel Ae ae 9 Capture Zone Models inn caida dt 9 IN EE 10 Data Mp as 11 Running AM A A A A A eee 12 R n Time Error Message diiniita 13 Model Output les is Zeie uedgetiesgd e pudiendo it rd 14 Mode rpm ll od 14 DEA o sd 14 EquipotentialS vi ici 14 Equipotential SU ACE initial jodas 15 ECO ee EE 15 e EE 15 Example Problems an enea Eed dee EE 17 Example 1 Steady State 1 Pumping Well
11. Model run TOPO is executed in Full Screen mode When the TOPO menu appears press the F2 key to view the graphics When finished press ESC and lt Enter to return to Windows Figure 4 shows an equipotential contour plot from Example 1 WellWare AqModel for Windows User s Manual 15 Equipotential Surface Double click on the icon labeled Equipotential Surface to create a surface plot of equipotentials from the most recent AqModel run SURF is executed in Full Screen mode When the SURF menu appears press the F2 key to view the graphics When finished press ESC and lt Enter to return to Windows Figure 5 shows an equipotential surface plot from Example 1 Stream Functions Double click on the icon labeled Stream Functions to create a contour plot of stream functions from the most recent AqModel run TOPO is executed in Full Screen mode When the TOPO menu appears press the F2 key to view the graphics When finished press ESC and lt Enter to return to Windows Figure 6 shows a stream function contour plot from Example 1 Flow Nets Double click on the icon labeled Flow Net to create a flow net plot from the most recent AqModel run You must first create plot files for Equipotentials EQUIPLOT PLT and Stream Functions STREAMEN PLT by double clicking on their respective icons as described above and by creating the PLT files from TOPO s Output menu Make sure this is done each time you want a flow net to ensure that old
12. OS is a registered trademark and Windows is a trademark of Microsoft Corporation PostScript is a registered trademark of Adobe Systems Incorporated SURFER is a registered trademark of Golden Software Inc Golden Colorado WellWare AqModel for Windows User s Manual 22 References Bear J 1979 Hydraulics of Groundwater McGraw Hill Inc New York NY 569p Freeze R A and J A Cherry 1979 Groundwater Prentice Hall Englewood Cliffs N J 604p Jacob C E 1950 Flow of Groundwater Engineering Hydraulics ed H Rouse John Wiley and Sons New York pp 321 386 Javandel I Doughty C and C F Tsang 1984 Groundwater Transport Handbook of Mathematical Models AGU Water Resources Monograph 10 Washington D C 228 p Javandel I and C F Tsang 1986 Capture Zone Type Curves A Tool for Aquifer Cleanup Ground Water Vol 24 No 5 pp 616 625 McWhorter D B and D K Sunada 1977 Ground Water Hydrology and Hydraulics Water Resources Publications Fort Collins CO 290p O Neill G T 1990 Modeling Approaches for Hydraulic Control of Groundwater Contamination Proc Hazardous Materials Control Research Institute s HMC Great Lakes 90 Conference Session on Contaminated Groundwater Control Sept 26 28 1990 Cleveland Ohio pp 112 116 O Neill G T 1992 RessqM User s Manual WellWare Zheng C 1989 PATH3D A Ground Water Path and Travel Time Simulator User s Manual S S P
13. PLT files are replaced with the most recent AqModel results Flow Net appends STREAMFN PLT to EQUIPLOT PLT to create a new file called FLOWNET PLT and then executes SURFER s VIEW in Full Screen mode VIEW automatically draws the flow net on the screen When finished press the ESC key select Quit from the menu and press lt Enter to return to Windows Note that VIEW is useful for viewing PLT files Figure 7 shows the flow net from Example 1 obtained by combining the plots of Figure 4 and Figure 6 AqModel can also create flow nets for the steady state case when there are no wells pumping Simply specify NW 0 or set Q 0 for each pumping or recharge well in an existing data set see APPENDIX A There will be no drawdown and the equipotentials and stream functions may be combined to create a flow net which shows the regional aquifer flow due to hydraulic gradient and transmissivity alone This type of plot as shown on Figure 8 from Example 1 may be useful to depict the amount of groundwater flow passing a given boundary drawn on a map that the flow net is superimposed on The flow across the boundary is obtained by simply counting the number of streamlines that cross the boundary and multiplying by the constant contour interval 1See Model Graphics WellWare AqModel for Windows User s Manual 16 The traditional graphical method of constructing flow nets emphasizes drawing curvilinear squares throughout the region Then the d
14. apadopulos amp Associates Inc 7944 Wisconsin Avenue Bethesda MD 20814 Zheng C G D Bennett and C B Andrews 1991 Analysis of Ground Water Remedial Alternatives at a Superfund Site Ground Water Vol 29 No 6 pp 838 848 WellWare AqModel for Windows User s Manual Figure 1 Using PREAQM to Create EXAMPLE1 DAT PREAOM Version 1 11 for Windows TM A Data Preprocessor for AqModel Version 2 11 Copyright C 1990 1993 by Gerald T O Neill WellWare Please Enter AgqModel Data File Name EXAMPLE1 DAT Please Enter Title for the Simulation in Single Quotes AqModel Example 1 Steady State 1 Pumping Well Number of Pumping and or Recharge Wells Storage Coefficient Input 0 for Steady State Number of Observation Wells Direction of Regional Flow in degrees Hydraulic Gradient of Regional Flow Aquifer Transmissivity in ft 2 day Aquifer Thickness in inimum X Coordinate of Model aximum X Coordinate of Model inimum Y Coordinate f Model aximum Y Coordinate of Model in Enter Pumping or Recharg Well Data Enter OX ft OY ft Q gpm 0 2500 200 Pump Well EL single quotes Enter Observation Well Data T Enter XO ft YO ft WLABEL in single quotes 0 1000 Obs Well 1 Enter Observation Well Data 2 Enter XO ft YO ft WLABEL in single quotes 4000 4000 Obs Well 2 Stop Program terminated Wel
15. ault value for hp 100 ft at the point x 0 y 0 Numerical values of steady state drawdown calculated by AqModel should be taken as approximate due to the difficulty in estimating a realistic value of R the distance beyond which drawdown is negligible AqModel uses a default value of R 20 000 ft If the distance between points XMIN YMIN and XMAX YMAX specified by the user is greater than 20 000 ft AqModel adds that distance to R In effect AqModel assumes the distance to negligible steady state drawdown is beyond the limits of the model area In WellWare AqModel for Windows User s Manual 8 the above equation R gt r and since R appears as log R even large errors in estimating R do not appreciably affect the resulting drawdown calculations Because steady flow cannot exist in an infinite aquifer the radius of influence is a problematic term The flow is unsteady where a transient state describes the temporal features of unsteady flow until a recharge source is intercepted by the expanding cone of depression It is perhaps more constructive to think of R as being the distance at which the aquifer head remains constant Although steady state and uniform flow conditions are not often met in the field analyses based on these assumptions are nevertheless practical and useful It remains the responsibility of the user of a model to correctly apply it in a meaningful way If a time dependent head distribution is desired the so
16. brary AqModel Program Manager group file ream Function Example gram indows nk WellWare AqModel for Windows User s Manual 6 Quick Start If you do not wish to read the manual at this time and have already installed SURFER and AqModel see Software Installation simply start Windows and then double click on the AqModel Program Group Icon in Program Manager to open the AqModel Group Then simply double click on the icon corresponding to the task you wish to perform wc Program Manager File Options Window Help PREAGM AgqModel UNITS Drawdown Equipotentials E quipotential Stream Flow Net Notepad d Surface Functions 233 i Microsoft Excel Word for hDC Power Accessories Visual Basic Windows 2 0 Launcher Desktop aaa aaa Age Age Programming Utilities Microsoft Tools Games WellWare AqModel for Windows User s Manual 7 AqModel AqModel Aquifer Model is a general aquifer modeling program for calculating drawdown potential distribution and stream functions Practical uses of the model include well field simulation flow net generation and determination of capture zones of single or multiple well recovery systems AqModel is also useful for determining well head protection areas AqModel is an analytical groundwater flow model which yields an exact solution to the problem of wells pumping in a confined aquifer under uniform flow conditions homogeneous and isotropic transmiss
17. ch time AqModel is run You can open and print this file from most any text or word processor including the Windows Notepad Run Time Error Message If you experience the following error message while running AqModel run time error M6202 MATH log SING error Edit LINE 9 in the AqModel data set with an editor or word processing program Change the values of NX and NY see APPENDIX A by successively increasing both numbers by 1 from 61 default to 62 63 and run AqModel again until you no longer get the error This error message occurs when a grid calculation point or node falls on a well location Changing the number of calculation points will also change their locations and therefore fix the error without causing a loss in accuracy of the solution WellWare AqModel for Windows User s Manual 14 Model Output Files AqModel creates four output files for each model run during steady state simulations The output files are deleted and replaced with new ones for each subsequent model run Therefore be sure to rename output files that you wish to save by using the File Manager The output files are described in the following DRAWDOWN GRD drawdown ft at each calculation node in the model area EQUIPLOT GRD hydraulic head ft at each calculation node STREAMFN GRD stream function gpm at each calculation node AQMODEL TXT listing of model data and drawdown at observation wells Note If a transi
18. e well that arrive at the pumping well Therefore about 90 gpm of recharged water is ultimately pumped back out Using RESSQ Javandel et al 1984 p 54 determined the approximate arrival times of water moving along the streamlines from the recharge well to the pumping well The range was from about 3 to 22 years WellWare AqModel for Windows User s Manual 20 RESSQ has been described as being user hostile O Neill 1990 1992 has modified RESSQ to include a data preprocessor and to interface with SURFER for custom graphics This useful code called RessqM is now available Contact WellWare for more information Figure 13 shows a flow net plot for Example 5 WellWare AqModel for Windows User s Manual 21 Tips COPY CENTERED SYM from C SURFER to C AQMODELW if you plan to use centered symbols to enhance your plots post data etc To create PLT files and print or plot graphics from SURFER go to TOPO s or SURF s Output menu and select Send plot to installed output device and press lt Enter SURFER s VIEW program is useful for viewing PLT files Acknowledgments Gerald T O Neill is grateful to Dr Chunmiao Zheng of S S Papadopulos amp Associates Inc for his assistance in writing the solution for handling the discontinuity in stream functions at a well Gerald T O Neill is grateful to Milovan S Beljin of HydroLink for the UNITS program DXF is a trademark of AutoDesk Inc MS D
19. easily provides solutions to each of these tasks The data set EXAMPLE1 DAT and the output shown on Figures 1 through 6 were generated by using PREAQM and AqModel as discussed previously AqModel output is listed on Figure 2 and in the diskette file EXAMPLE1 TXT Figure 3 shows a contour plot of Drawdown from Example 1 Drawdown is concentric around the pumping well located at the center of the plot The contour interval is 0 5 ft Note that the Observation Wells are located between the 2 5 and 3 ft contours the drawdown shown on Figure 2 is 2 75 ft Since both wells are equidistant from the pumping well they have the same drawdown Figure 4 shows a contour plot of Equipotentials from Example 1 AqModel assumes an initially planar water table or equipotential surface with an aquifer reference head of 100 ft at the point x 0 y 0 The direction of groundwater flow is 45 degrees measured counterclockwise from the positive X axis water level elevations decline in this direction according to the hydraulic gradient of 0 002 ft ft or about 10 ft mile The drawdown produced by the single pumping well is added to the water level decline by uniform groundwater flow to determine the head at each node Figure 5 shows a surface plot of Equipotentials from Example 1 This type of plot is useful for showing the features of the equipotential surface However note the illusion of the great pumping depression the vertical scale is about 300 times
20. ent simulation is requested S is not equal to zero then only the heads and drawdown are calculated and STREAMFN GRD is not obtained This is because stream functions are not defined in unsteady flows A listing of AQMODEL TXT for EXAMPLE1 DAT is shown on Figure 2 Model Graphics Each GRD file can be read directly by Golden Software s SURFER to contour the heads drawdown and stream functions Although WellWare assumes that users are familiar with SURFER preformatted SURFER command files CMD are provided with AqModel to make creating graphics an easy and effective process for the novice as well as the experienced SURFER user To create PLT files and print or plot graphics from SURFER go to TOPO s or SURF s Output menu and select Send plot to installed output device and press Enter Examples of AqModel graphics are shown on the Figures and are presented in the section Example Problems The various types of AqModel graphics are discussed below Drawdown Double click on the icon labeled Drawdown to create a contour plot of drawdown from the most recent AqModel run SURFER s TOPO program is executed in Full Screen mode When the TOPO menu appears press the F2 key to view the graphics When finished press ESC and lt Enter to return to Windows Figure 3 shows a drawdown contour plot from Example 1 Equipotentials Double click on the icon labeled Equipotentials to create a contour plot of equipotentials from the most recent Aq
21. ischarge through any part of the streamtube is calculated from the flow in one element By contouring the stream function at a constant interval the discharge through each streamtube is the same Obtaining perfect curvilinear squares is not essential to drawing flow nets with AqModel as long as a constant known contour interval is used to draw the streamlines Admittedly the flow net elements on Figures 7 and 8 are somewhat rectangular rather than perfectly square But this does not diminish the utility of these plots in the slightest However it is also true that square elements are more attractive The squareness can be improved by selecting appropriate contour intervals for both the equipotential and stream function plots WellWare AqModel for Windows User s Manual 17 Example Problems Data sets for the following example problems are provided on the accompanying disk These are intended as an introduction to using AqModel Example 1 and Example 5 will be presented in some detail in the following Users are encouraged to run these problems and experiment with the data sets Example 1 Steady State 1 Pumping Well This problem involves a single pumping well in uniform flow The problem is to determine the distribution of drawdown and water levels in the aquifer In addition we desire a plot of the groundwater pathlines and a flow net And we want to know the location of the capture zone As demonstrated in the following AqModel
22. ivity AqModel is applicable to two dimensional uniform groundwater flows with multiple pumping and or recharge wells Golden Software s SURFER is required for AqModel graphics on a PC AqModel generates GRD files in SURFER format and AqModel ships with preformatted command files for controlling various aspects of graphics creation using SURFER s TOPO contour maps and SURF 3D surface plots routines These files make it easy to run AqModel and create graphics with SURFER in the Windows environment SURFER supports a wide variety of graphics cards monitors printers including PostScript and plotters and graphics formats including AutoCAD DXF and HPGL Used in conjunction with SURFER AqModel is a powerful groundwater analytical and presentation tool Drawdown and Potential Distribution The head distribution for steady state conditions is determined by superposition of solutions for uniform flow and equilibrium drawdown Thiem by multiple wells N A 1 R hy y hp i xcosa ysina iat Qin j l where hx y is the head at any point x y in the aquifer hp is the initial head at a point in the aquifer 1 is the hydraulic gradient and o is the direction of uniform groundwater flow T is the aquifer transmissivity Qj is the discharge or recharge rate at well j N is the number of wells R is the radius of influence of the well and r is the radial distance from the well to the point x y AqModel assumes a def
23. lWare AqModel for Windows User s Manual Figure 2 Listing of AqModel Output File AQMODEL TXT From Example 1 AqModel Version 2 11 for Windows TM Copyright C 1990 1993 by Gerald T O Neill All Rights Reserved WellWare AqModel Example 1 Steady State 1 Pumping Well STEADY STATE SIMULATION Aquifer Parameters Number of Wells 1 Storage Coefficient 0000E 00 Direction of Groundwater Flow 45 00 degrees Gradient of Groundwater Flow 2000E 02 Aquifer Transmissivity 5000 00 ft 2 day Aquifer Thickness 100 00 ft Calculation Grid Xmin 00 ft Xmax 5000 00 Ymin 00 ft Ymax 5000 00 Number of Nodes in X direction 61 Number of Nodes in Y direction 61 Well Data X ft Y EE Flow gpm Well Label 2500 00 2500 00 200 00 Pump Well Total Pumping Rate 200 00 gpm Drawdown Results X ft Y ft Drawdown ft Well Label 1000 00 1000 00 2 75 Obs Well 1 4000 00 4000 00 2 75 Obs Well 2 WellWare AqModel User s Guide Figure 3 AqModel Examplel Drawdown Contour Plot Drawdown Contours in ft 0 1008 2008 3009 406068 5222 5000 5000 4000 4000 4 3200 30098 c 2000 2008 gt 1008 1900 0 lt 9 0 1008 2008 3000 4000 5220 x In Ft 3160 Woods Circle WellWare Davis CA 95616 916 758 0290 Effective Sofrware for Groundwater Professionals AqModel User s Guide Figure 4 AqModel Example1 Equipotential Contour Plot Equipotential Contours in ft e
24. leS Stream Function Contour Plot Contours of Stream Function tn gpm 6562 4562 2562 562 1438 3438 5438 gt PA 5438 3438 q 1438 562 2562 4562 562 e 6562 Sees 2562 562 1438 3438 5438 x distance In ft WellWar E Davs cA sscie 916 758 0290 Effective Software for Groundwater Professionals tn ft Y AqModel User s Guide Figure 13 AqModel Example5 Flow Net Fiow Net 6562 4562 2562 562 1438 3438 5438 TY 7 Y 5438 Ee 3438 1438 6562 d Zi 6562 4562 2562 5662 1438 3438 5438 Xx In TL 3160 Woods Circle WellWar Davis CA 95616 916 758 0290 Effective Software for Groundwater Professionals AqModel User s Guide APPENDIX A AqModel Data 1003 Prospect Hts Santa Cruz CA 95065 408 426 8260 WellWare Effective Software for Groundwater Prof AqModel User s Guide Table 1 AqModel Data File Format DATA FILE LINE LINE 1 LINE 2 LINE 3 LINE 4 LINE 5 LINE 6 LINE 7 LINE 8 LINE 9 LINE 10 LINE 11 LINE 12 Repeat NW LINE 12 NW LAST LINE Repeat IOBS Important Notes VARIABLE TITLE NW IOBS ALPHA GRAD T B NX NY XMIN XMAX YMIN YMAX OX QY O WLABEL TIME XO YO WLABEL Data variables are described in Table 2 Data variables may be separated by spaces a tab ora comma on LINE 9 12 andthe LAST LINE listed above DATA TYPE CHARACTER INTEGER REAL INTEGER REAL RE
25. lution is given by superposition of solutions for uniform flow and transient drawdown Theis by multiple wells N 1 hx y hp i xcosa ysina AnT YQW u j l where W u ody y and o 4Tt W u is the so called well function of u and is calculated for values of u from a polynomial approximation to the exponential integral written as an infinite series y is a dummy variable of integration S is the storage coefficient and t is time Pumping Near Hydrogeologic Boundaries The influence of hydrogeologic straight line boundaries can be approximately simulated with AqModel using the method of images A constant head boundary can be simulated by using a line of recharge wells and a no flow boundary can be simulated using a line of pumping wells Refer to texts on groundwater hydrology for an explanation of the method of images and its application e g Bear 1979 Freeze and Cherry 1979 Stream Functions Stream functions denoted by the symbol H are functions that are everywhere tangent to the specific discharge vector Contours of the stream function are called streamlines In steady state flow streamlines indicate the direction of flow at every point see WellWare AqModel for Windows User s Manual 9 APPENDIX B AqModel calculates stream functions for the model area by adding the stream functions for uniform and radial flow N Y Ki ycosa xsina n SQ tan 1 2 jel where K is the hydraulic conducti
26. n any form or by any means electronic or mechanical including photocopying scanning and recording for any purpose other than the purchaser s personal use without the written permission of WellWare and Gerald T O Neill The software programs on the accompanying disk may not be copied except to install on one computer hard disk and for backup purposes only by the original purchaser WellWare AqModel for Windows User s Manual 3 AqModel Requirements e IBM PC 386 SX or higher or 100 compatible microcomputer with hard disk drive MS DOS 5 0 or higher and Windows Version 3 1 or higher Windows must be run in 386 Enhanced Mode e Golden Software Inc SURFER version 4 or higher and SURFER compatible graphics adapter monitor and printer or plotter e A math coprocessor is used if present however it is not required Software Installation SURFER SURFER is required for AqModel graphics on a PC It is not included with AqModel and can be purchased from Golden Software Inc by calling 1 800 333 1021 or 1 303 279 1021 SURFER should be installed before using AqModel and must be available to AqModel through the DOS PATH command The following shows one way of correctly configuring SURFER for use with AqModel Install SURFER in a directory called C SURFER Add SURFER to the PATH command in the AUTOEXEC BAT file as follows PATH C C DOS C SURFER etc e Restart the computer e At the DOS prom
27. nuity in stream functions at the well This is a problem for us only because it blemishes an otherwise beautiful plot The simple solution is to ignore it if you can it is not an error in the model However the problem cannot be easily corrected because we re using a contouring program to draw streamlines The plot on the cover of the manual once looked like this but was then improved by a graphic artist who erased the thick line and connected the streamlines This is a good technique for final presentations Another suggestion is to increase the number of calculation points NX and NY which will result in a thinner line and also consume more disk space The capture zone of the single pumping well can be identified on this plot by contouring the stream function at a sufficiently small interval The capture zone in two dimensions is the area of aquifer which contributes flow to the well The capture zone can be defined by the dividing streamline that separates flow to the well from that which passes the well The stream function was contoured at a 5 gpm interval to produce Figure 6b Note the velocity stagnation point downstream of the well This point is located at the intersection of the dividing streamline and a line in the direction of flow at a distance from the well given by Q Xs 2mbq where q Ki is the specific discharge A quick hand calculation yields Xs 610 ft approximately The scale on Figure 6b is 1 inch 12
28. ource identification and contaminant properties should be considered as well as the overall management of the well field But groundwater flow path delineation is an important part and AqModel can provide some assistance where the flows do not depart significantly from the assumptions of uniform steady flow For more realistic modeling of groundwater flow paths in complex aquifers refer to Zheng 1989 WellWare AqModel for Windows User s Manual 11 Data Input Input to AqModel consists of one data set The data file may be created with conventional text editors or word processing programs or by using PREAQM the preprocessor provided with AqModel To run PREAQM simply double click on its icon Enter data by typing responses to PREAQM prompts and then by pressing the lt Enter key The following figure shows part of the interactive PREAQM screen display with data from EXAMPLE1 DAT On Line Help is available for the PREAQM Windows interface Select Index from the Help menu for a hypertext list of menu commands and procedures for which help is available PREAGMYW Unit File Edit View State Window Help PREAQH Version 1 11 for Windows TH A Data Preprocessor for Aqhodel Version 2 11 Copyright C 1996 1993 by Gerald T O Neill WellWare TH 3717 Modoc PL Davis CA 95616 Please Enter Aqhodel Data File Name EXAMPLEA1 DAT Please Enter Title for the Simulation in Single Quotes lAghodel Example 1 Steady State 1 Pumping Well
29. own above a negative number may be used e g 20 340 The gradient of uniform regional groundwater flow in ft ft dimensionless Aquifer transmissivity in ft2 day Aquifer thickness in ft Number of calculation nodes in X direction Default is NX 61 Maximum value of NX 101 1003 Prospect Hts Santa Cruz CA 95065 408 426 8260 WellWare Effective Software for Groundwater Prof NY XMIN XMAX YMIN YMAX QX QY Q WLABEL TIME XO YO WLABEL AqModel User s Guide Number of calculation nodes in Y direction Default is NY 61 Maximum value of NY 101 Minimum value of X coordinate of model area in ft Maximum value of X coordinate of model area in ft Minimum value of Y coordinate of model area in ft Maximum value of Y coordinate of model area in ft The X coordinate of a pumping or recharge well in ft The Y coordinate of a pumping or recharge well in ft The pumping or recharge rate of a well in gpm A label for each pumping or recharge well May contain up to 10 characters that must be enclosed in single quotes Time of transient simulation in days SKIP THIS LINE IF S 0 The X coordinate of an observation well in ft The Y coordinate of an observation well in ft A label for each observation well May contain up to 10 characters that must be enclosed in single quotes 1003 Prospect Hts Santa Cruz CA 95065 408 426 8260 WellWare Effective Soft
30. pt configure SURFER for your video hardware and output device by typing the following commands PLOT i lt Enter This command will configure your output device printer plotter graphics file format for use with SURFER VIEW i lt Enter This command will configure your video display for use with SURFER WellWare AqModel for Windows User s Manual 4 AqModel Installation 1 Start Microsoft Windows ze Insert the AqModel diskette into the appropriate drive A or B 3 Select Run from the Program Manager File menu and type A INSTALL or B INSTALL and then press lt Enter or choose the OK button 4 INSTALL will copy AqModel files to your C drive into a directory named CAAQMODELW 5 a Create a new group for AqModel in Program Manager From the File menu choose New The New Program Object dialog box appears New Program Object b Select the Program Group option and then choose the OK button The Program Group Properties dialog box appears Program Group Properties Description AqModel Group File c In the Description box type AqModel In the Group File box type C AQMODELW AQMODEL and then choose the OK button The AqModel Group appears the following view is maximized Paan E Gegen Die Sr ADC File Options Window Help El PREAGM AgqModel UNITS Drawdown Equipotentials i Equipotential Stream Flow Net Notepad Surface Functions 6 Installation is now complete We s
31. uggest that you review this User s Manual and the Example Problems before using AqModel WellWare Diskette Files AqModel for Windows User s Manual 5 The following files are found on the accompanying diskette INSTALL EQUIPLOT EQUISURF DRAWDOWN BAT BAT BAT BAT STREAMFN BA FLOWNET STR Kl D DRAWDOWN CMD EQUIPLOT EQUISURF FN BAT CMD EXAMPLE DA EXAMPLE TX AQMODELW E PREAOMW UNITS EXE AQMODE 1 IL AQMODEL GRP A batch file for installing AqModel A batch file for running TOPO to pl A batch file for running TOPO to pl A batch file for running SURF to pl surface A batch file for running TOPO to pl functions A batch file for creating and viewi A TOPO command file for creating Dr on a hard disk ot drawdown ot equipotentials ot equipotential ot stream ng flow nets awdown contours A TOPO command file for creating Equipotential contours A SURF command file for creating Equipotential surface POES A TOPO command file for creating St contours An AqModel example data set Corresponding model output file for AqModel for Windows application pro Data preprocessor for AqModel for W Units conversion program by HydroLi AqModel icon li
32. ults What does a negative value for drawdown mean How do the equipotential and streamline patterns differ from the case where the well is pumping What if the direction of flow were 225 degrees in this example Example 3 Transient 1 Pumping Well This is a transient problem similar to Example 1 AqModel output is listed in EXAMPLE3 TXT Note that stream functions are not computed Example 4 Transient 1 Recharge Well This is the equivalent of Example 3 where the well is now recharging AqModel output is listed in EXAMPLE4 TXT Example 5 Steady State 1 Pumping Well and 1 Recharge Well This is a steady state problem with 1 pumping well and 1 recharge well This problem is derived from Example 2 of Javandel et al 1984 p 48 for the RESSQ model AqModel output is listed in EXAMPLES TXT Figure 9 shows contours of drawdown around the pumping and recharge wells Note the zero drawdown contour between the wells Figure 10 shows the equipotential pattern developed in the vicinity of the wells Compare this plot with those from Examples 1 and 2 Note that the flow direction here is also 45 degrees Figure 11 depicts the natural gradient and the effects of the buildup of head due to the recharge well and the drawdown due to pumping Figure 12 shows the streamline pattern Observe that water flows from the recharge well to the pumping well The contour interval is approximately 10 gpm There are 9 streamlines leaving the recharg
33. vity and b is the aquifer thickness see e g McWhorter and Sunada 1977 Unconfined Aquifers AqModel can be applied to unconfined aquifers where the drawdown is small in comparison with the saturated aquifer thickness For flow in unconfined aquifers that satisfies this requirement use T Kb where b is the initial saturated aquifer thickness and replace S with Sy specific yield of unconfined aquifer in the AqModel data set see APPENDIX A This method makes use of the Dupuit assumptions and fails when vertical flow components are significant See Jacob 1950 for more information Capture Zone Models AqModel facilitates determination of capture zones by calculating stream functions which are then contoured using SURFER to show the streamlines or groundwater pathlines By definition no flow crosses a streamline The streamline that separates flow to the well from that which passes the well is called the dividing streamline Thus the dividing streamline outlines the capture zone It may be determined by calculating the stream function at sufficient density and shown by contouring the stream function at a sufficiently small contour interval An example of using AqModel to determine the capture zone of a single pumping well is presented in detail in the section Example Problems see Example 1 AqModel has been compared with other popular models for determining well capture zones including RESSQ Javandel et al 1984 and PATH3D Zheng
34. ware for Groundwater Prof AqModel User s Guide APPENDIX B Modeling Approaches for Hydraulic Control of Groundwater Contamination by Gerald T O Neill WellWare Note WellWare was formerly Software Solutions for Groundwater Hydrologists 1003 Prospect Hts Santa Cruz CA 95065 408 426 8260 WellWare Effective Software for Groundwater Prof AqModel User s Guide 1003 Prospect Hts Santa Cruz CA 95065 408 426 8260 WellWare Effective Software for Groundwater Prof
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