USGS Groundwater Information
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
A summary list of computer models that simulate ground-water flow and quality is presented. The list contains a brief description of each model program, its numerical features, a qualitative expression of the number of past applications, the reference for the report documenting the program, and where to obtain a copy. Reports included in the list have been published or developed by the U.S. Geological Survey, and contain listings of the computer programs, although in a few cases, the program is so long that a listing was not included in the report, but a copy of the program is available on request.
Numerical models provide a powerful aid in understanding and assessing ground-water systems. The U.S. Geological Survey (USGS) has contributed significantly to the development and use of models for the analysis of ground-water problems. Two reports had previously documented the status of ground-water modeling in the USGS, Appel and Bredehoeft (1976) and Appel and Reilly (1988). Because developments in the field have taken place since that time, additional computer programs have been published. This report gives information on selected computer programs published or developed by the USGS or by the USGS in cooperation with Federal, State, and local agencies for modeling flow, quality, and solute or heat transport in ground-water systems. The information for each program includes the reference, a brief description of the field conditions that the program can simulate, the numerical approximation procedures used, an indication of the extent of past field appl ications of the program by USGS personnel, and where to obtain copies of the report and, in some cases, the computer code.
The list of programs is organized by general modeling category. Information on each program is separated by one solid horizontal line. In many cases a program is based on or related to another program. The parent program is listed first and followed by the related programs. Three solid lines mark the end of the list of those programs related to a parent computer program. In a few cases, however, a program listed under one category was derived from a program in another category; for example, some of the programs listed in the "Freshwater-Saltwater" category are modifications to ground-water flow programs described in the category "Flow-Saturated." Also, some programs could be included under other categories; for example, the programs by Grove and Stollenwerk (1984) and Lewis, Voss, and Rubin (1986) are models for the transport of fluids that are affected by physical and chemical processes. Both of those programs could have been include d in the "Chemical Mass Transfer" category instead of the category of "Solute Transport" in which they are contained in this report. Although several flow models that account for surface-water interaction are listed as having been derived from some parent flow model, we have listed the coupled ground- and surface-water flow model of Swain and Wexler (1993) separately even through it represents a coupling of the ground-water flow model of McDonald and Harbaugh (1988) and a surface-water flow model of Schaffranek, Baltzer, and Goldberg (1981). This choice was made to bring attention to the fact that it is the only case in which the surface-water formulation is based on a comprehensive set of unsteady flow equations, which are subject only to the limitations inherent in a one-dimensional formulation of streamflow. The intent of these examples is to indicate that a potential user should thoroughly evaluate the programs in all related categories to choose the most ap propriate numerical tool. The category titles are generalized and are not intended to be all-inclusive.
Depending on the nature of the problem, more than one computer program may apply. In some cases, the choice of program may reflect more the individual's familiarity with a particular approach than the superiority of the approach. In other cases, the choice of program may definitely reflect the level of approximation required; for example, if field data indicate a thick zone of brackish water that separates strictly fresh water from strictly salt water, then the choice of a program that assumes the zone is an interface may result in a lesser level of approximation than would a solute-transport program that includes consideration of the density variations in the zone.
Many computer programs for the simulation of ground-water flow and quality are listed herein. Some of these programs are listed for historical reasons or because they represent specialized aspects of either physics or chemistry. Additionally, many areas of ground-water flow and chemistry are the subjects of multiple investigations, in which related programs are developed in an attempt to refine and (or) perfect the methods currently available; therefore, some aspects of ground water can be simulated by more than one model listed in this report. Although the reports that document the programs have been reviewed and approved, not all parts of every program have necessarily been thoroughly tested, and a user bears the ultimate responsibility for assuring that a program does, in fact, what is claimed. Confidence in a program increases with good agreement between program results and known solutions to problems closely related to those for which the program is intended to solve.
As an indication of models that are currently "popular," a poll was made in late 1992 of model usage in the U.S. Geological Survey's operational program. The models being used at that time are listed in table1. This listing provides general information on usage. However, new codes or specialty codes may not be included (or may be under represented) in this table simply because of the available utility of the codes at the start of these projects and the scope of the current projects being undertaken. Associated with many of the computer programs discussed in this report are acronyms. Appendix 1 gives a list of those acronyms and the full name of the corresponding program and the appropriate reference(s).
This report makes available a moderately comprehensive list of computer programs that have been produced by the U.S. Geological Survey for simulation of ground-water flow and quality. The main criterion used in compiling the list is that the program must be documented in a published report that includes a listing of the computer program, although in a few cases, the program is so long that a listing was not included in the report, but a copy of the program is available on request.
For those reports not available from a cooperating State agency, an indication is given from which of the following Federal sources the report and computer program can be obtained:
U.S. Geological Survey
NTIS, U.S. Department of Commerce
U.S. Geological Survey Open-File Reports and Water-Resources Investigations Reports, can be purchased from:
U.S. Geological Survey Water-Supply Papers, Professional Papers, Bulletins, Circulars, and Techniques of Water-Resources Investigations, can be purchased from:
USGS Map Distribution