Summary of selected computer programs produced by the U.S. Geological Survey for simulation of ground-water flow and quality - 1994

U.S. Geological Survey Circular 1104

by C.A. Appel and T.E. Reilly

SUMMARY AND CLOSING REMARKS

The computer programs listed in this report have been published or developed by the U.S. Geological Survey and solve problems that concern the physics and chemistry of ground water. Some programs are included for either historical purposes or documentation of a specific method. Thus, not all programs are being widely used. Some programs have been released so recently that the statements on past applications cannot indicate the potential usefulness of these programs. A few programs have been or are being used in many studies and have been so noted.

REFERENCES CITED

Appel, C.A., and Bredehoeft, J.D., 1976, Status of ground-water modeling in the U.S. Geological Survey: U.S. Geological Survey Circular 737, 9 p.

Appel, C.A., and Reilly, T.E., 1988, Selected reports that include computer programs produced by the U.S. Geological Survey for simulation of ground-water flow and quality: U.S. Geological Survey Water-Resources Investigations Report 87-4271, 64 p.

Ball, J.W., Jenne, E.A., and Cantrell, M.W., 1981, WATEQ3--A geochemical model with uranium added: U.S. Geological Survey Open-File Report 81-1183, 81 p.

Ball, J.W., Jenne, E.A., and Nordstrom, Darrell K., 1979, WATEQ2--A computerized chemical model for trace and major element speciation and mineral equilibrium of natural waters, in Jenne, E. A., ed., Chemical modeling in aqueous systems: American Chemical Society Symposium Series 93, p. 815-836.

Ball, J.W., and Nordstrom, D.K., 1991, User's manual for WATEQ4F, with revised thermodynamic data bases and test cases for calculating speciation of major, trace, and redox elements in natural waters: U.S. Geological Survey Open-File Report 91-183, 189p., with diskette in pocket.

Ball, J.W., Nordstrom, D.K., and Jenne, E.A., 1980, Additional and revised thermochemical data and computer code for WATEQ2--A computerized chemical model for trace and major element speciation and mineral equilibria of natural waters: U.S. Geological Survey Water-Resources Investigations Report 78-116, 109 p. (Second printing, 1981.)

Ball, J.W., Nordstrom, D.K., and Zachmann, D.W., 1987, WATEQ4F--A personal computer FORTRAN translation of the geochemical model WATEQ2 with revised data base: U.S. Geological Survey Open-File Report 87-50, 108 p.

Barnes, I., and Clarke, F.E., 1969, Chemical properties of ground water and their encrustation effects on wells: U.S. Geological Survey Professional Paper 498-D, 58 p.

Bodine, M.W., Jr., and Jones, B.F., 1986, THE SALT NORM--A quantitative chemical-mineralogical characterization of natural waters: U.S. Geological Survey Water-Resources Investigations Report 86-4086, 130 p.

_____, 1990, normative analysis of ground waters from the Rustler Formation associated with the Waste Isolation Pilot Plant (WIPP), southeastern New Mexico, in Spencer, R.J., and Chou, I-Ming, eds., Fluid-mineral interactions--A tribute to H.P. Eugster: The Geochemical Society Special Publication 2, p. 213-269.

Bredehoeft, J.D., 1992, Microcomputer codes for simulating transient ground-water flow--In two and three space dimensions: U.S. Geological Survey Open-File Report 90-559, 73 p., computer diskette in pocket.

Bredehoeft, J.D., and Pinder, G.F., 1970, Digital analysis of areal flow in multiaquifer ground-water systems--A quasi three-dimensional model: Water Resources Research, v. 6, no. 3, p. 883-888.

Cooley, R.L., 1992, Derivation of finite-element equations and comparisons with analytical solutions: Part 2 of a MODular Finite-Element model (MODFE) for areal and axisymmetric ground-water-flow problems: U.S. Geological Survey Techniques of Water-Resources Investigations, book 6, chap. A4, 108 p.

_____, 1993, Supplement 1 -- Modifications to the computer code for nonlinear regression solution of steady-state ground-water flow problems; Supplement 1 of Regression modeling of ground-water flow: Techniques of Water-Resources Investigations of the U.S. Geological Survey, Book 3, Chapter B4, Supplement 1, 8 p.

Cooley, R.L., and Naff, R.L., l990, Regression modeling of ground-water flow: Techniques of Water Resources Investigations of the U.S. Geological Survey, book 3, chap. B4, 232 p., with diskette in pocket.

DaCosta, J.A., and Bennett, R.R., 1960, The pattern of flow in the vicinity of a recharging and discharging pair of wells in an aquifer having areal parallel flow: International Association of Scientific Hydrology Publication 52, p. 524-536.

Darcy, Henry, 1856, Les Fontaines publiques de la ville de Dijon: Paris, Victor Dalmont, 647 p.

DeBraal, J.D., and Kharaka, Y.K., 1989, SOLINPUT--A computer code to create and modify input for the geochemical program SOLMINEQ.88: U.S. Geological Survey Open-File Report 89-616, 140 p.

Dunlap, L.E., Lindgren, R.J., and Carr, J.E., l984, Projected effects of ground-water withdrawals in the Arkansas River Valley, l980-99, Hamilton and Kearny Counties--southwestern Kansas: U.S. Geological Survey Water-Resources Investigations Report 84-4082, l68 p.

Durbin, T.J., 1978, Calibration of a mathematical model of the Antelope Valley ground-water basin, California: U.S. Geological Survey Water-Supply Paper 2046, 51 p.

Engesgaard, Peter, and Kipp, K.L., 1992, A geochemical transport model for redox-controlled movement of mineral fronts in groundwater flow systems:--A case of nitrate removal by oxidation of pyrite: Water Resources Research, v. 28, no. 10, p. 2829-2843.

Essaid, H.I., 1990, SHARP--A quasi-three-dimensional finite-difference simulation model for freshwater and saltwater flow in layered coastal aquifer systems: U.S. Geological Survey Water-Resources Investigations Report 90-4130, 181 p.

Faust, C.R., and Mercer, J.W., l977, A finite-difference model of two-dimensional, single- and two-phase heat transport in a porous medium: version I--U.S. Geological Survey Open-File Report 77-234, 47 p.

Fleming, G.W., and Plummer, L.N., 1983, PHRQINPT--An interactive computer program for constructing input data sets to the geochemical simulation program PHREEQE: U.S. Geological Survey Water-Resources Investigations Report 83-4236, 108 p.

Garabedian, S.P., 1986, Application of a parameter-estimation technique to modeling the regional aquifer underlying the eastern Snake River Plain, Idaho: U.S. Geological Survey Water-Supply Paper 2278, 60 p.

Garabedian, S.P., and Konikow, L.F., l983, Front-tracking model for convective transport in flowing ground water: U.S. Geological Survey Water-Resources Investigations Report 83-4034, 55 p.

Glover, K.C., 1987, A dual-porosity model for simulating solute transport in oil shale: U.S. Geological Survey Water-Resources Investigations Report 86-4047, 88 p.

_____, 1988, A finite-element model for simulating hydraulic interchange of surface and ground water: U.S. Geological Survey Water-Resources Investigations Report 86-4319, 90 p.

Glynn, P.D., 1991a, MBSSAS--A code for the computation of Margules parameters and equilibrium relations in binary solid-solution aqueous-solution systems: Computers and Geoscience, v. 17, no. 7, p. 907-966.

_____, 1991b, Effect of impurities in gypsum on contaminant transport at Pinal Creek, Arizona, in Mallard, G. E., and Aronson, D.A., eds., U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the technical meeting, Monterey, California, March 11-15, 1991: U.S. Geological Survey Water-Resources Investigations Report 91-4034, p. 466-474.

Glynn, P.D., Engesgaard, Peter, and Kipp, K.L., 1991, Use and limitations of two computer codes for simulating geochemical mass transport at the Pinal Creek Toxic-Waste Site, in Mallard, G. E., and Aronson, D.A., eds., U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the technical meeting, Monterey, California, March 11-15, 1991: U.S. Geological Survey Water-Resources Investigations Report 91-4034, p. 454-460.

Goode, D.J., and Appel, C.A., 1992, Finite-difference interblock transmissivity for unconfined aquifers and for aquifers having smoothly varying transmissivity: U.S. Geological Survey Water-Resources Investigations Report 92-4124, 79 p.

Goode, D.J., and Konikow, L.F., 1989, Modification of a method-of-characteristics solute-transport model to incorporate decay and equilibrium-controlled sorption or ion exchange: U.S. Geological Survey Water-Resources Investigations Report 89-4030, 65 p.

Grove, D.B., and Stollenwerk, K.G., l984, Computer model of one-dimensional equilibrium-controlled sorption processes: U.S. Geological Survey Water-Resources Investigations Report 84-4059, 58 p.

Guswa, J.H., and LeBlanc, D.R., l985, Digital models of ground-water flow in the Cape Cod aquifer system, Massachusetts: U.S. Geological Survey Water-Supply Paper 2209, 112 p.

Hansen, A.J., Jr., 1993, Modifications to the modular three-dimensional finite-difference ground-water flow model used for the Columbia Plateau regional aquifer-system analysis, Washington, Oregon, and Idaho: U.S. Geological Survey Open-File Report 91-532, 162 p.

Harbaugh, A.W., 1990a, A simple contouring program for gridded data: U.S. Geological Survey Open-File Report 90-144, 37 p.

_____, 1990b, A computer program for calculating subregional water budgets using results from the U.S. Geological Survey modular three-dimensional finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 90-392, 46 p.

_____, 1992, A generalized finite-difference formulation for the U.S. Geological Survey modular three-dimensional finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 91-494, 60 p.

Hayba, D.O., and Ingebritsen, S.E., in press, The computer model HYDROTHERM, A three-dimensional finite-difference model to simulate ground-water flow and heat transport in the temperature range of 0 to 1,200 oC: U.S. Geological Survey Water-Resources Investigations Report 94-4045.

Healy, R.W., 1987, Simulation of trickle irrigation, an extension to the U.S. Geological Survey's computer program VS2D: U.S. Geological Survey Water-Resources Investigations Report 87-4086, 61 p.

_____, 1990, Simulation of solute transport in variably saturated porous media with supplemental information on modification to the U.S. Geological Survey's computer program VS2D: U.S. Geological Survey Water-Resources Investigations Report 90-4025, 125 p.

Hearne, G.A., l982, Supplement to the New Mexico three-dimensional model: U.S. Geological Survey Open-File Report 82-857, 90 p.

Helgesen, J.O., Larson, S.P., and Razem, A.C., l982, Model modifications for simulation of flow through stratified rocks in eastern Ohio: U.S. Geological Survey Water-Resources Investigations Report 82-40l9, l09 p.

Hill, M.C., 1990, Preconditioned Conjugate-Gradient 2 (PCG2) -- A computer program for solving ground-water flow equations: U.S. Geological Survey Water-Resources Investigations Report 90-4048, 43 p.

_____, 1992, A computer program (MODFLOWP) for estimating parameters of a transient, three-dimensional, ground-water flow model using nonlinear regression: U.S. Geological Survey Open-File Report 91-484, 358 p.

_____, 1994, Five computer programs for testing weighted residuals and calculating linear confidence and prediction intervals on results from the ground-water parameter-estimation computer program MODFLOWP: U.S. Geological Survey Open-File Report 93-481, 81 p.

Hsieh, P.A., and Freckleton, J.R., 1993, Documentation of a computer program to simulate horizontal-flow barriers using the U.S. Geological Survey modular three-dimensional finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 92-477, 32 p.

Hutchinson, C.B., Johnson, D.M., and Gerhart, J.M., l98l, Hydrogeology of well-field areas near Tampa, Florida, Phase 1--Development and documentation of a two-dimensional finite-difference model for simulation of steady-state ground-water flow: U.S. Geological Survey Open-File Report 8l-630, l29 p.

INTERA Environmental Consultants, Inc., l979, Revision of the documentation for a model calculating effects of liquid waste disposal in deep saline aquifers: U.S. Geological Survey Water-Resources Investigations Report 79-96, 79 p.

INTERCOMP Resource Development and Engineering, Inc., l976, A model for calculating effects of liquid waste disposal in deep saline aquifers: U.S. Geological Survey Water-Resources Investigations Report 76-6l, 263 p.

Ishii, A.L., Healy, R.W., and Striegl, R.G., 1989, A numerical solution for the diffusion equation in hydrogeologic systems: U.S. Geological Survey Water-Resources Investigations Report 89-4027, 86 p.

Jones, B.F., and Llamas, M.R., 1989, Normative analysis of ground waters from the Madrid Basin, Spain, in Miles, Douglas L., ed., Water-rock interaction (WRI-6)--Proceedings of the 6th International Symposium on Water-Rock Interactions, August 3-8, 1989, Malvern, England: Rotterdam, Balkema, p. 341-347.

Kharaka, Y.K., and Barnes, Ivan, 1973, SOLMNEQ--Solution-mineral equilibrium computations: U.S. Geological Survey Computer Contribution, National Technical Information Service PB-215 899, 81 p.

Kharaka, Y.K., Gunter, W.D., Aggarwal, P.K., Perkins, E.H., and DeBraal, J.D., 1988, SOLMINEQ.88--A computer program for geochemical modeling of water-rock interactions: U.S. Geological Survey Water-Resources Investigations Report 88-4227, 420 p.

Kipp, K.L., Jr., 1987, HST3D--A computer code for simulation of heat and solute transport in three-dimensional ground-water flow systems: U.S. Geological Survey Water-Resources Investigations Report 86-4095, 5l7 p.

Konikow, L.F., and Bredehoeft, J.D., l978, Computer model of two-dimensional solute transport and dispersion in ground water: Techniques of Water-Resources Investigations of the United States Geological Survey, book 7, chap. C2, 90 p.

Kontis, A.L., and Mandle, R.J., 1988, Modification of a three-dimensional ground-water flow model to account for variable water density and effects of multiaquifer wells: U.S. Geological Survey Water-Resources Investigations Report 87-4265, 78 p.

Kuiper, L.K., 1983, A numerical procedure for the solution of the steady state variable density groundwater flow equation: Water Resources Research, v. 19, no. 1, p. 234-240.

_____, l985, Documentation of a numerical code for the simulation of variable density ground-water flow in three dimensions: U.S. Geological Survey Water-Resources Investigations Report 84-4302, 80 p.

_____, 1987, Computer program for solving ground-water flow equations by the preconditioned conjugate gradient method: U.S. Geological Survey Water-Resources Investigations Report 87-4091, 34 p.

Kuniansky, E.L., 1990, A finite-element model for simulation of two-dimensional steady-state ground-water flow in confined aquifers: U.S. Geological Survey Open-File Report 90-187, 77 p.

Lappala, E.G., Healy, R.W., and Weeks, E.P., 1987, Documentation of computer program VS2D to solve the equations of fluid flow in variably saturated porous media: U.S. Geological Survey Water-Resources Investigations Report 83-4099, 184 p.

Larson, S.P., l978, Direct solution algorithm for the two-dimensional ground-water flow model: U.S. Geological Survey Open-File Report 79-202, 22 p.

Leahy, P.P., l982, A three-dimensional ground-water flow model modified to reduce computer-memory requirements and better simulate confining-bed and aquifer pinchouts: U.S. Geological Survey Water-Resources Investigations 82-4023, 59 p.

Leake, S.A., Leahy, P., and Navoy, A.S., in press, Documentation of a computer program to simulate transient leakage from confining units using the modular finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 94-59.

Leake, S.A., and Prudic, D.E., 1991, Documentation of a computer program to simulate aquifer-system compaction using the modular finite-difference ground-water flow model: Techniques of Water-Resources Investigations of the United States Geological Survey, book 6, chap. A2, 68 p.

Lefkoff, L.J., and Gorelick, S.M., 1987, AQMAN--Linear and quadratic programming matrix generator using two-dimensional ground-water flow simulation for aquifer management modeling: U.S. Geological Survey Water-Resources Investigations Report 87-4061, 164 p.

Lewis, F.M., Voss, C.I., and Rubin, Jacob, l986, Numerical simulation of advective-dispersive multisolute transport with sorption, ion exchange and equilibrium chemistry: U.S. Geological Survey Water-Resources Investigations Report 86-4022, l65 p.

Mallory, M.J., l979, Documentation of a finite-element two-layer model for simulation of ground-water flow: U.S. Geological Survey Water-Resources Investigations Report 79-l8, 347 p.

Manteuffel, T.A., Grove, D.B., and Konikow, L.F., l983, Application of the conjugate-gradient method to ground-water models: U.S. Geological Survey Water-Resources Investigations Report 83-4009, 24 p.

McDonald, M.G., and Harbaugh, A.W., l988, A modular three-dimensional finite-difference ground-water flow model: Techniques of Water-Resources Investigations of the United States Geological Survey, book 6, chap. A1, 586 p.

McDonald, M.G., Harbaugh, A.W., Orr, B.R., and Ackerman, D.J., 1992, A method of converting no-flow cells to variable-head cells for the U.S. Geological Survey modular finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 91-536, 99 p.

Mercer, J.W., Larson, S.P., and Faust, C.R., l980, Finite-difference model to simulate the areal flow of saltwater and freshwater separated by an interface: U.S. Geological Survey Open-File Report 80-407, 88 p.

Mercer, J.W., and Pinder, G.F., l975, A finite-element model of a two-dimensional, single-phase heat transport in a porous medium: U.S. Geological Survey Open-File Report 75-574, ll5 p.

Meyer, W.R., and Carr, J.E., l979, A digital model for simulation of ground-water hydrology in the Houston area, Texas: Texas Department of Water Resources Report LP-l03, 27 p. (Appendix, l07 p.)

Miller, R.S., 1988, User's guide for RIV2--A package for routing and accounting of river discharge for a modular, three-dimensional, finite-difference, ground-water flow model: U.S. Geological Survey Open-File Report 88-345, 33 p.

Nordstrom, D.K., Plummer, L.N., Langmuir, D., Busenberg, Eurybiades, May, H.M.,

Jones, B.F., and Parkhurst, D.L., 1990, Revised chemical equilibrium data for major water-mineral reactions and their limitations, in Melchior, D. C., and Bassett, R. L., eds., Chemical modeling of aqueous systems II: American Chemical Society Symposium Series 416, p. 398-413.

Nordstrom, D.K., Plummer, L. N., Wigley, T.M.L., Wolery, T.J., Ball, J.W., Jenne, E.A., Bassett, R.L., Crerar, D.A., Florence, T.M., Fritz, B., Hoffman, M., Holdren, G.R., Jr., Lafon, G.M., Mattigod, S.V., McDuff, R.E., Morel, F., Reddy, M.M., Sposito, G., and Thrailkill, J., 1979, A comparison of computerized chemical models for equilibrium calculations in aqueous systems: American Chemical Society Symposium Series 93, p. 857-892.

Nordstrom, D.K., Valentine, S.D., Ball, J.W., Plummer, L.N., and Jones, B.F., 1984, Partial compilation and revision of basic data in the WATEQ programs: U.S. Geological Survey Water-Resources Investigations Report 84-4186, 40 p.

Orzol, L.L., and McGrath, T.S., 1992, Modifications of the U.S. Geological Survey modular, finite-difference, ground-water flow model to read and write geographical information system files: U.S. Geological Survey Open-File Report 92-50, 202 p.

Ozbilgin, M.M., and Dickerman, D.C., l984, A modification of the finite-difference model for simulation of two-dimensional ground-water flow to include surface-ground water relationships: U.S. Geological Survey Water-Resources Investigations Report 83-425l, 98 p.

Parkhurst, D.L., Plummer, L. N., and Thorstenson, D.C., 1982, BALANCE--A computer program for calculating mass transfer for geochemical reactions in ground water: U.S. Geological Survey Water-Resources Investigations Report 82-14, 29 p.

Parkhurst, D.L., Thorstenson, D.C., and Plummer, L.N., 1980, PHREEQE--A computer program for geochemical calculations: U.S. Geological Survey Water-Resources Investigations Report 80-96, 195 p. (Revised 1990.)

Pinder, G.F., and Voss, C.I., 1979, AQUIFEM--A finite-element model for aquifer evaluation (Documentation): Department of Water Resources Engineering, Royal Institute of Technology, Stockholm, Sweden, Report 7911, TRITA-VAT-3806, 107 p.

Plummer, L.N., Jones, B.F., and Truesdell, A.H., 1976, WATEQF-A FORTRAN IV version of WATEQ--A computer program for calculating chemical equilibrium of natural waters: U.S. Geological Survey Water-Resources Investigations Report 76-13, 70 p. (Revised 1984.)

Plummer, L.N., Parkhurst, D.L., Fleming, G.W., and Dunkel, S.A., 1988, A computer program incorporating Pitzer's equations for calculation of geochemical reactions in brines: U.S. Geological Survey Water-Resources Investigations Report 88-4153, 310 p., and two diskettes in pocket.

Plummer, L.N., Parkhurst, D.L., and Kosiur, D.R., 1976, MIX2--A computer program for modeling chemical reactions in natural waters: U.S. Geological Survey Water-Resources Investigations Report 75-6l, National Technical Information Service Report PB-251 668, 73 p.

Plummer, L.N., Parkhurst, D.L., and Thorstenson, D.C., 1983, Development of reaction models for ground-water systems: Geochimica et Cosmochimica Acta, v. 47, p. 665-686.

Plummer, L.N., Prestemon, E.C., and Parkhurst, D.L., 1991, An interactive code (NETPATH) for modeling net geochemical reactions along a flow path: U.S. Geological Survey Water-Resources Investigations Report 91-4078, 227 p., with diskette in pocket.

Pollock, D.W., 1989, Documentation of computer programs to compute and display pathlines using results from the U.S. Geological Survey modular three-dimensional finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 89-381, 188 p.

_____, 1990, A Graphical Kernel System (GKS) version of computer program MODPATH-PLOT for displaying path lines generated from the U.S. Geological Survey three-dimensional ground-water flow model: U.S. Geological Survey Open-File Report 89-622, 49 p.

Posson, D.R., Hearne, G.A., Tracy, J.V., and Frenzel, P.F., l980, A computer program for simulating geohydrologic systems in three dimensions: U.S. Geological Survey Open-File Report 80-42l, 795 p.

Prudic, D.W., 1989, Documentation of a computer program to simulate stream-aquifer relations using a modular, finite-difference, ground-water flow model: U.S. Geological Survey Open-File Report 88-729, 113 p.

Pucci, A.A., Jr., and Pope, D.A., 1987, Preprocessor and postprocessor computer programs for a radial-flow, finite-element model: U.S. Geological Survey Open-File Report 87-680, 69 p.

Puig, J.C., and Rolon-Collazo, L.I., in press, User's manual for AQMAN3D--A mathematical programming system dataset generator for aquifer management using the U.S. Geological Survey modular three-dimensional finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 92-481.

Reed, J.E., l985, Digital model for simulating steady-state ground-water and heat flow: U.S. Geological Survey Water-Resources Investigations Report 85-4248, l34 p.

Reed, J.E., Bedinger, M.S., and Terry, J.E., l976, Simulation procedure for modeling transient water-table and artesian stress and response: U.S. Geological Survey Open-File Report 76-792, l73 p.

Reilly, T.E., l984, A Galerkin finite-element flow model to predict the transient response of a radially symmetric aquifer: U.S. Geological Survey Water-Supply Paper 2l98, 33 p.

Reilly, T.E., and Harbaugh, A.W., 1993a, Simulation of cylindrical flow to a well using the U.S. Geological Survey Modular Finite-Difference Ground-Water Flow Model: Ground Water, v. 31, no. 3, p. 489-494.

_____, 1993b, Source code for the computer program and sample data set for the simulation of cylindrical flow to a well using the U.S. Geological Survey modular finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 92-659, 7 p., with diskette in pocket.

Rutledge, A.T., 1991, An axisymmetric finite-difference flow model to simulate drawdown in and around a pumped well: U.S. Geological Survey Water-Resources Investigations Report 90-4098, 33 p.

Sanford, W.E., and Konikow, L.F., l985, A two-constituent solute-transport model for ground water having variable density: U.S. Geological Survey Water-Resources Investigations Report 85-4279, 88 p.

_____, 1989, Simulation of calcite dissolution and porosity changes in saltwater mixing zones in coastal aquifers: Water Resources Research, v. 25, no. 4, p. 655-667.

Sapik, D.B., 1988, Documentation of a steady-state saltwater-intrusion model for three-dimensional ground-water flow, and user's guide: U.S. Geological Survey Open-File Report 87-526, 174 p.

Sato, M., 1960, Oxidation of sulfide ore bodies: Econ Geology, v. 55, p. 928-961, 1202-1231.

Schaffranek, R.W., Baltzer, R.A., and Goldberg, D. E., 1981, A model for simulation of flow in singular and interconnected channels: U.S. Geological Survey Techniques of Water-Resources Investigations, book 7, chap. C3, 110 p.

Scott, J.C., 1990, A statistical processor for analyzing simulations made using the modular finite-difference ground-water flow model: U.S. Geological Survey Water-Resources Investigations Report 89-4159, 218 p.

Souza, W.R., 1987, Documentation of a graphical display program for SUTRA finite-element simulation model: U.S. Geological Survey Water-Resources Investigations Report 87-4245, 122 p.

Swain, E.D., 1993, Documentation of a computer program (Streamlink) to represent direct-flow connections in a coupled ground-water and surface-water model: U.S. Geological Survey Water-Resources Investigations Report 93-4011, 62 p.

Swain, E.D., and Wexler, E.J., 1993, A coupled surface-water and ground-water flow model for simulation of stream-aquifer interaction: U.S. Geological Survey Open-File Report 92-138, 162 p.

Torak, L.J., l982, Modifications and corrections to the finite-difference model for simulation of three-dimensional ground-water flow: U.S. Geological Survey Water-Resources Investigations Report 82-4025, 30 p.

Torak, L.J, 1993a, Model description and user's manual, Part 1 of A MODular Finite-Element model (MODFE) for areal and axisymmetric ground-water-flow problems: U.S. Geological Survey Techniques of Water-Resources Investigations, book 6, chap. A3, 136 p.

_____, 1993b, Design philosophy and programming details, Part 3 of A MODular Finite-Element model (MODFE) for areal and axisymmetric ground-water-flow problems, part 3: U.S. Geological Survey Techniques of Water-Resources Investigations, book 6, chap. A5, 243 p.

Torak, L.J., and Whiteman, C.D., Jr., l982, Applications of digital modeling for evaluating the ground-water resources of the "2,000-foot" sand of the Baton Rouge area, Louisiana: Louisiana Department of Transportation and Development, Office of Public Works, Water Resources Technical Report 27, 87 p.

Trescott, P.C., l975, Documentation of finite-difference model for simulation of three-dimensional ground-water flow: U.S. Geological Survey Open-File Report 75-438, 32 p.

Trescott, P.C., and Larson, S.P., l976, Supplement to Open-File Report 75-438--Documentation of finite-difference model for simulation of three-dimensional ground-water flow: U.S. Geological Survey Open-File Report 76-59l, 17 p.

Trescott, P.C., Pinder, G.F., and Larson, S.P., l976, Finite-difference model for aquifer simulation in two dimensions with results of numerical experiments: Techniques of Water-Resources Investigations of the United States Geological Survey, book 7, chap. C1, 116 p.

Truesdell, A.H., and Jones, B.F., 1973, WATEQ--A computer program for calculating chemical equilibrium of natural waters: National Technical Information Service PB-220 464, 77 p.

____, 1974, WATEQ--A computer program for calculating chemical equilibrium of natural waters: U.S. Geological Survey, Journal of Research, v. 2, no. 2, p. 233-248.

Voss, C.I., l984a, A finite-element simulation model for saturated-unsaturated, fluid-density-dependent ground-water flow with energy transport or chemically-reactive single-species solute transport: U.S. Geological Survey Water-Resources Investigations Report 84-4369, 409 p.

_____, 1984b, AQUIFEM-SALT--A finite element model for aquifers containing a seawater interface: U.S. Geological Survey Water-Resources Investigations Report 84-4263, 37 p.

Weeks, J.B., l978, Digital model of ground-water flow in the Piceance Basin, Rio Blanco and Garfield Counties, Colorado: U.S. Geological Survey Water-Resources Investigations 78-46, 108 p.

Weiss, Emanuel, l982, A model for the simulation of flow of variable-density ground water in three dimensions under steady-state conditions: U.S. Geological Survey Open-File Report 82-352, 59 p.