NAME
moc3d - Three-dimensional method-of-characteristics ground-water
flow and transport model
ABSTRACT
This model simulates three-dimensional solute transport in flowing
ground water. The model computes changes in concentration of a
single dissolved chemical constituent over time that are caused by
advective transport, hydrodynamic dispersion (including both
mechanical dispersion and diffusion), mixing (or dilution) from
fluid sources, and mathematically simple chemical reactions
(including linear sorption, which is represented by a retardation
factor, and decay). The model can also simulate ground-water age
transport and the effects of double porosity and zero-order
growth/loss.
METHOD
The transport model is integrated with MODFLOW, a three-dimensional
ground-water flow model that uses implicit finite-difference methods
to solve the transient flow equation. MOC3D uses the method-of-
characteristics to solve the transport equation on the basis of the
hydraulic gradients computed with MODFLOW for a given time step.
Particle tracking is used to represent advective transport and
explicit finite-difference methods are used to calculate the effects
of other processes.
HISTORY
Version 3.01 1999/07/08 - Bug fixed in double porosity routine.
Version 3.0 1999/03/24 - Added capabilities to simulate age
transport, double porosity exchange, and simple reactions. The
simple reactions include cell-by-cell terms for decay and zero-
order growth/loss. Decay and growth coefficients can change in
time at the beginning of each flow model stress period.
Version 2.02 1999/03/08 - Added the elapsed transport time to the
header information for particle output files.
Version 2.01 1999/01/25 - Altered the replacement scheme for
particles entering the subgrid to fix distribution problems for
weakly divergent flow fields near subgrid boundaries.
Version 2.0 1998/11/16 - Added implicit dispersive transport
algorithm, rearranged main.f file to call a MOC3D control module
(moc_main.f), added new output option for printing concentrations
in "table" style, FHB package added, added printing of time step
and stress period in MOC3D output file, fixed velocity
calculation bug (KSTP>1, ISS=0), corrected calculation of subgrid
face counter, fixed bug in mass balance calculation for decay,
fixed sign in saturated thickness calculation, corrected check
for porosity vs. storage terms, typographical errors fixed.
Version 1.2 1998/05/01 - Output control for particles (NPNTPL)
fixed; automatic initialization for retardation factor (RF)
fixed, bug in crch5.f fixed, single header line for CNCA and VELA
files, test for rounding error in move.f fixed, HFB1 and DE45
packages added, mass balance loop error fixed, some output
formats changed.
Version 1.1 1997/05/14 - Minor bug fixes affecting a format
statement and output of initial condition data to observation
well file.
Version 1.0 1996/11/08 - Initial release
DATA REQUIREMENTS
Initial conditions, boundary conditions, aquifer properties at every
node, and grid descriptors.
OUTPUT OPTIONS
See documentation.
SYSTEM REQUIREMENTS
MOC3D is written in Fortran 77 with the following extensions: use
of variable names longer than 6 characters, use of more than 19
continuation lines, and a common block with character and
noncharacter variables. By default, the software is dimensioned for
use with models having up to 20,000 cells and 200,000 particles.
MOC3D requires that file names required for the simulation be
defined prior to execution. Two Name Files (MODFLOW and MOC3D) must
be used for this purpose. The format of these is described in the
documentation. Generally, the program is easily installed on most
computer systems. The code has been used on UNIX-based computers
and DOS-based 386 or greater computers having a math coprocessor.
DOCUMENTATION
Goode, D.J., 1999, Age, double porosity, and simple reaction
modifications for the MOC3D ground-water transport model: U.S.
Geological Survey Water-Resources Investigations Report 99-4041,
34 p.
Kipp, K.L., Jr., Konikow, L.F., and Hornberger, G.Z., 1998, An
implicit dispersive transport algorithm for the U.S. Geological
Survey MOC3D solute-transport model: U.S. Geological Survey
Water-Resources Investigations Report 98-4234, 54 p.
Konikow, L.F., Goode, D.J., and Hornberger, G.Z., 1996, A three-
dimensional method-of-characteristics solute-transport model
(MOC3D): U.S. Geological Survey Water-Resources Investigations
Report 96-4267, 87 p.
The basic MODFLOW documentation is contained in the following three
reports:
McDonald, M.G., and Harbaugh, A.W., 1988, A modular three-
dimensional finite-difference ground-water flow model: U.S.
Geological Survey Techniques of Water-Resources Investigations,
book 6, chap. A1, 586 p.
Harbaugh, A.W., and McDonald, M.G., 1996, User's documentation for
MODFLOW-96, an update to the U.S. Geological Survey modular
finite-difference ground-water flow model: U.S. Geological Survey
Open-File Report 96-485, 56 p.
Harbaugh, A.W., and McDonald, M.G., 1996, Programmer's documentation
for MODFLOW-96, an update to the U.S. Geological Survey modular
finite-difference ground-water flow model: U.S. Geological Survey
Open-File Report 96-486, 220 p.
RELATED DOCUMENTATION
Konikow, L.F., Granato, G.E., and Hornberger, G.Z., 1994, User's
guide to revised method-of-characteristics solute-transport model
(MOC--Version 3.1): U.S. Geological Survey Water-Resources
Investigations Report 94-4115, 63 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.
Konikow, L.F., and Bredehoeft, J.D., 1978, Computer model of two-
dimensional solute transport and dispersion in ground water:
U.S. Geological Survey Techniques of Water-Resources
Investigations, book 7, chap. C2, 90 p.
TRAINING
Modeling Transport of Ground-Water Solutes (GW2080TC), offered
annually at the USGS National Training Center.
CONTACTS
Operation and Distribution:
U.S. Geological Survey
Hydrologic Analysis Software Support Program
437 National Center
Reston, VA 20192
h2osoft@usgs.gov
Official versions of U.S. Geological Survey water-resources analysis
software are available for electronic retrieval via the World Wide
Web (WWW) at:
http://water.usgs.gov/software/
and via anonymous File Transfer Protocol (FTP) from:
water.usgs.gov (path: /pub/software).
The WWW page and anonymous FTP directory from which the MOC3D
software can be retrieved are, respectively:
http://water.usgs.gov/software/moc3d.html
--and--
/pub/software/ground_water/moc3d
See http://water.usgs.gov/software/ordering_documentation.html for
information on ordering printed copies of USGS publications.
SEE ALSO
mfi(1) - A preprocessor for MODFLOW
moc(1) - Two-dimensional method-of-characteristics ground-water
flow and transport model
modflw96(1) - Modular three-dimensional finite-difference ground-
water flow model
modflow-gui(1) - Preprocessor and postprocessor graphical-user
interfaces for preparing MODFLOW-96 and MOC3D
input data and viewing model output for use within
Argus Open Numerical Environments (Argus ONE)
Modflowp(1) - Parameter-estimation version of the modular model
sutra(1) - Saturated and (or) unsaturated, constant or
variable-density fluid flow, and solute or energy
transport (2-dimensional finite-element code)
vs2di(1) - A graphical software package for simulating fluid flow
and solute or energy transport in variably saturated
porous media