GROUND WATER -- Simulation of contaminant movement

                        GEOLOGICAL SURVEY
                        RESTON VIRGINIA  22092

                                                  Code 4351 5016

                                             February 8, 1978


SUBJECT:  GROUND WATER -- Simulation of contaminant movement

Because the contamination of a ground-water resource is a serious
problem that may have long-term economic, social, and physical
consequences, methods are needed to predict the effects of man's
activities on ground-water quality.  Reliable predictions of
contaminant movement can only be made if we understand the
processes controlling the convective transport, hydrodynamic
dispersion, and chemical reactions affecting the concentration of
dissolved chemicals in ground water, and if we can quantitatively
represent them in a systematic model.  Aquifers generally have
heterogeneous properties and irregular boundary conditions;
therefore, the solution of the mathematical equations that
describe the transport processes generally requires the use of
deterministic, distributed parameter, digital simulation models.

The enclosed report, "Computer model of two-dimensional solute
transport and dispersion in ground water," by L. F. Konikow and
J.D. Bredehoeft, is a comprehensive documentation of one such model.
The model represents a valuable tool that can be used in the
analysis of ground-water quality changes.  Its capability for
computing the movement of dissolved chemicals in flowing ground
water can help in (1) understanding the causes of observed
concentration patterns, (2) estimating future changes in chemical
concentration with time and space, (3) planning and designing
projects to minimize ground-water contamination, (4) estimating
the time of travel between a source of contamination and a ground-
water discharge or observation point, such as a stream, spring, or
well, (5) designing an effective and efficient monitoring system,
and (6) evaluating the physical and economic feasibility of
alternative reclamation plans for removing contaminants from an
aquifer or preventing contaminants from spreading.

The report was released as Techniques of Water-Resources
Investigations, Book 7, Chapter C2.  The program is general and
flexible in that it can be readily and directly applied to a wide
variety of field problems.  However, in some cases it may have to
be modified by the user for efficient application to his specific
field problem.  The numerical procedure uses a finite-difference
approximation to solve the ground-water flow equation and the
method of characteristics to solve the solute-transport equation.
The model assumes that the solute is nonreactive and that
differences in fluid density, viscosity, and temperature do not
affect fluid velocity.

The program is written in FORTRAN IV, and the report includes a
program listing.  The source deck and compiled program are
available on the IBM and Honeywell MULTICS (Reston and Denver)
systems.  On the IBM, a load module (program number K590) is
available using SYS1.LOADLIB on either RE1 or RE2.  Following is a
sample JCL sequence to execute this program:

//         JOB (...)

On the Honeywell, segments moc.fortran, which is the source code,
and moc, which is the object code, are accessible in directory
>udd>Transport>LKonikow.  Additional instructions for retrieval or
use can be obtained from the Ground Water Branch.  The data
requirements, input format specifications, program options, and
output formats are all structured in a general manner that should
be readily adaptable to many field problems.  The report includes
input and output examples from a sample problem.

                              (s) Leonard F. Konikow
                              (for) Chief, Ground Water Branch


WRD Distribution: A, B, S, FO