U.S. Geological Survey modflow(1)
NAME
modflow - Modular three-dimensional finite-difference
ground-water model
ABSTRACT
MODFLOW is a three-dimensional finite-difference ground-
water model that was first published in 1984. It has a modular
structure that allows it to be easily modified to adapt the
code for a particular application. Many new capabilities have
been added to the original model. OFR 00-92 (complete reference
below) documents a general update to MODFLOW, which is called
MODFLOW-2000 in order to distinguish it from earlier versions.
MODFLOW-2000 simulates steady and nonsteady flow in an
irregularly shaped flow system in which aquifer layers can
be confined, unconfined, or a combination of confined and
unconfined. Flow from external stresses, such as flow to
wells, areal recharge, evapotranspiration, flow to drains,
and flow through river beds, can be simulated. Hydraulic
conductivities or transmissivities for any layer may differ
spatially and be anisotropic (restricted to having the
principal directions aligned with the grid axes), and the
storage coefficient may be heterogeneous. Specified head
and specified flux boundaries can be simulated as can a head
dependent flux across the model's outer boundary that allows
water to be supplied to a boundary block in the modeled area
at a rate proportional to the current head difference
between a "source" of water outside the modeled area and the
boundary block. MODFLOW is currently the most used
numerical model in the U.S. Geological Survey for ground-
water flow problems.
In addition to simulating ground-water flow, the scope of
MODFLOW-2000 has been expanded to incorporate related
capabilities such as solute transport and parameter estimation.
METHOD
The ground-water flow equation is solved using the finite-
difference approximation. The flow region is subdivided
into blocks in which the medium properties are assumed
to be uniform. In plan view the blocks are made from
a grid of mutually perpendicular lines that may be
variably spaced. Model layers can have varying thickness.
A flow equation is written for each block, called a cell.
Several solvers are provided for solving the resulting matrix
problem; the user can choose the best solver for the particular
problem. Flow-rate and cumulative-volume balances from each
type of inflow and outflow are computed for each time step.
HISTORY
MODFLOW-2000 Version 1.18.00 2007/08/23 - Added the SWT Package to
support simulation of subsidence in water-table aquifers. It also
includes bug fixes.
MODFLOW-2000 Version 1.17.04 2007/08/03 - This release includes bug
fixes and minor changes. Bug fixes and other changes are described
in release.txt.
MODFLOW-2000 Version 1.17.02 2007/02/14 - This release includes bug
fixes and minor changes. Bug fixes and other changes are described
in release.txt.
MODFLOW-2000 Version 1.17.01 2006/09/22 - This is a bug-fix release.
Bug fixes are described in release.txt.
MODFLOW-2000 Version 1.17.00 2006/07/25 - The LAK3, SFR2, and GAG5
Packages have been updated to support simulation of new
capabilities. The GMG Package has been updated to support a new
adaptive-damping option. This version also includes a change in the
SUB Package and fixes for bugs in the ADV, MNW, and DRT Packages.
Please see release.txt and files referenced therein for details on
the new options and changes.
MODFLOW-2000 Version 1.16.00 2006/03/28 - The SFR2 Package replaces
the SFR1 Package of version 1.14.00, adding support for simulation
of unsaturated flow beneath streams. The ADV2 Package has been
made more compatible with MODPATH. Other changes and bug fixes
are described in release.txt.
MODFLOW-2000 Version 1.15.01 2005/04/05 - This is a bug-fix release.
Bug fixes are described in release.txt.
MODFLOW-2000 Version 1.15.00 2004/08/06 - Added the GMG Solver Package.
Modifications were made to the SFR Package.
MODFLOW-2000 Version 1.14.00 2004/07/01 - Added the SFR Package to
allow enhanced capabilities for simulation of streams. The maximum
number of layers is increased from 200 to 999.
MODFLOW-2000 Version 1.13.00 2004/01/22 - Includes revisions to the
LAK3 Package and bug fixes for the DRT, SUB, HUF2, and PCG2
Packages.
MODFLOW-2000 Version 1.12.01 2003/10/03 - This is a bug-fix release.
Bug fixes are described in release.txt.
MODFLOW-2000 Version 1.12 2003/09/08 - Added the SUB Package to allow
simulation of subsidence and aquifer-system compaction. The HUF
Package was upgraded from version 1 to version 2, providing support
for the new Layer Variable-Direction Horizontal Anisotropy (LVDA)
capability, an alternative specification of storage properties for
the uppermost active cells, calculation of flow in hydrogeologic
units, and the new Hydraulic-Conductivity Depth-Decay (KDEP)
capability. The ADV Package was updated from version 2.3 to version
2.4, which includes support for porosity parameters. Additional
enhancements and bug fixes are described in release.txt.
MODFLOW-2000 Version 1.11 2003/04/10 - Added the DAF Package to allow
coupling of MODFLOW with the Diffusion Analogy Surface-Water Flow
Model, and the MNW Package to allow simulation of well completed in
intervals represented by multiple model cells. New options for
showing progress of the simulation and controlling the calculation
of drawdowns have been added. Modifications to the PCG2 Package
affect the way DAMP works. Please see release.txt for information
on using these new packages, new options, and DAMP. This version
also includes a number of bug fixes and minor output changes, also
described in release.txt.
MODFLOW-2000 Version 1.10 2002/07/26 - Fixes bugs encountered when
compiling the source code distributed with version 1.9 and a
problem in a seldom-used part of the LMG Package.
MODFLOW-2000 Version 1.9 2002/07/15 - Updates were made to the LAK3,
GAGE5, and HUF1 Packages: (1) The LAK Package was modified to add
compatibility with the LPF and HUF packages and MODPATH, to clarify
output, and report cumulative lake budget; (2) Modifications to the
GAGE Package allow optional additional output related to lake gages;
and (3) A problem related to the calculation of horizontal-
conductance sensitivities was fixed in the HUF Package. Some
problems related to omission of observations (from the sum of
squared, weighted residuals objective function and other statistics
and the underscore ("_") output files) were corrected. Please see
the Release Notes in the file release.txt for more information
related to these issues.
MODFLOW-2000 Version 1.8 2002/05/01 - Added support for an option
that can be used to suppress printing of cell lists in any or all
of the RIV, GHB, DRN, DRT, HFB, WEL, and CHD Packages. This
version also includes fixes to (1) problems in the ADV Package
related to stagnant particles and incorrect sensitivities for
observation locations in confining units; (2) a bug that caused an
invalid value to be put into a hydraulic-property array when the
OBS Process was active and the PES Process was inactive; (3)
problems in LPF and HUF related to the sensitivity of vertical
conductance to head in the calculation of sensitivities for
unconfined cells; (4) a problem in HUF related to the rewetting
capability; (5) a problem in LMT related to use of the STR Package
and and the Extended-header option of LMT; and (6) problems in in
the RESAN2K post-processing program that affected ordering of
observation names and plot symbols.
MODFLOW-2000 Version 1.7 2001/12/04 - Added support for time-varying
parameters. Time-varying parameters are useful when the user
desires to estimate one parameter but vary properties included in
the parameter definition from one stress period to another.
Please see files Time-varying-parameters.pdf and str6.pdf in the
doc directory for details.
MODFLOW-2000 Version 1.6 2001/10/19 - Fixed two problems. The first
caused simulation time to be truncated, for runs that involve
calculation of sensitivities, to a simulation period one time step
too short when the last flow observation in a transient simulation
falls in a later time step than the final head observation. The
second problem caused observation sensitivities for constant-head
flow observations to be incorrect for log-transformed parameters.
In addition, support for new options for the name file was added to
allow users to designate files of type DATA, DATA(BINARY), DATAGLO,
or DATAGLO(BINARY) as either input or output files. Please see the
Release Notes in the file release.txt for a description of these
options.
MODFLOW-2000 Version 1.5 2001/08/16 - Added the LMT Package to
support generation of the link file required by the contaminant-
transport program MT3DMS.
MODFLOW-2000 Version 1.4 2001/07/10 - Added the LMG Package for
solving matrix equations using an algebraic multigrid solver.
MODFLOW-2000 Version 1.3 2001/06/11 - Fixed problem in LPF where if
a lower cell goes dry while the cell above is still wet, there
is a non-zero vertical conductance to a dry cell, causing
calculated heads and flows to be in error.
MODFLOW-2000 Version 1.2 2001/04/12 - Added support for using
vendor-specific options for opening unformatted (binary)
files. On personal computers, this can make it possible
for programs compiled by different compilers to write files
that have the same structure. The formula used to calculate
dimensionless, scaled sensitivities of simulated equivalents
to observations for log-transformed parameters is changed.
Other changes include bug fixes and clarification of output.
The MODFLOW-2000 distribution now includes Release Notes in
the file release.txt in the doc directory -- this file
describes in detail changes to MODFLOW-2000 for each version.
MODFLOW-2000 Version 1.1 2001/01/17 - Added IBS, HUF, LAK, ETS,
and DRT Packages. Added HYDMOD option. The EVT Package was
modified as described in the LAK documentation to include
the option (NEVTOP=3) to apply ET to the uppermost wet cell
in a vertical column of cells as done in the RCH Package.
MODFLOW-2000 Version 1.0 2000/07/20 - Enhanced modular structure
that facilitates the addition of broader capabilities such as
parameter estimation and solute transport. New data input
methods are included to support parameter estimation.
Vertical cell dimensions are specified in a separate
discretization file. A new package called the LPF Package
has been added as an alternative to the BCF Package.
The MODFLOW-2000 documentation report (OFR 00-92) does not
include the STR Package; however, this code has been upgraded
to use parameters and is included in this version of
MODFLOW-2000. Revised STR input instructions can be found
in file str6.pdf, which is included in the doc directory that
is part of the distribution for MODFLOW-2000.
The ADV Package has been modified for use with MODFLOW-2000.
Changes in input instructions are contained in file adv.txt,
which is also in the doc distribution directory.
The RES and FHB Packages are included in MODFLOW-2000 without
modification. These will work as before, but they do not
incorporate parameters or observations.
The IBS, TLK, and GFD Packages are not included in this
release. They require modification in order to work within
MODFLOW-2000.
Note that MODFLOW-2000 sends some messages to the computer
display. Some Fortran compilers make use of a reserved file
unit, for example unit 6, for output to the display. If such
compilers are used, it is important to avoid using a reserved
unit for any files in the MODFLOW name file.
MODFLOW-96 Version 3.3 2000/05/02 - Error fixed in IBS code that
caused incorrect values for critical head to be written when
the option is invoked to save these values in an external
file (variable IHCSV>0). The error did not affect the
actual interbed storage calculations, and none of the
other model results, such as computed head and budget
flows, are affected by the correction. There are no
changes to any other packages.
MODFLOW-96 Version 3.2 1998/01/09 - The Flow and Head Boundary Package,
Version 1, (FHB1) has been added. This package allows for
assignment of transient specified-flow and specified-head
boundaries in applications of MODFLOW-96. The FHB1
package is documented in U.S. Geological Survey Open-File
Report 97-571.
MODFLOW-96 Version 3.1 1997/03/11 - Calls to the Horizontal Flow
Barrier (HFB) Package have been corrected in the main
program. The main program for Version 3.0 incorrectly
calls the HFB1RP module where it should call the HFB1FM
module.
MODFLOW-96 Version 3.0 1996/12/03 - Updated version of overall model,
which is called MODFLOW-96. A number of changes were
made to make MODFLOW easier to use and easier to enhance.
MODFLOW-96 can use existing input data sets, and has the
same computational methods. Any package added to the
original model (now referred to as MODFLOW-88) will also
work with MODFLOW-96.
The Preconditioned Conjugate Gradient Package, Version 2
(PCG2) has been updated. This requires a minor change in
input data compared to the documentation in U.S.
Geological Survey Water-Resources Investigations Report
(WRIR) 90-4048 (full reference below). WRIR 90-4048
specifies two lines of input data. All of the data are
the same except the seventh value on the 2nd line. This
value is named IPCGCD in WRIR-4048, but it has been
replaced by a value named DAMP. That is, IPCGCD is no
longer part of the input data. DAMP can be used to
reduce oscillation when the solver is having difficulty
converging due to excessive oscillation. The value of
DAMP is multiplied times the head change calculated each
iteration at all cells. Thus, if DAMP is 0.5, the head
change is cut in half. If DAMP is 1.0, then PCG2 behaves
as it did prior to the addition of this capability. DAMP
should be set equal to 1.0 except when there is
indication of excessive oscillation. If the value of
DAMP is specified as 0.0 or less, it is automatically
changed to 1.0.
Also the sign of the C.B. STORAGE cell-by-cell budget
data in the TLK1 Package was changed to match the
standard sign convention in MODFLOW. The change to TLK1
does not impact computed heads or the overall volumetric
budget; it only affects data written to a cell-by-cell
budget file.
MODFLOW-88 Version 2.6 1996/09/20 - Added Reservoir package (RES1) as
documented in U.S. Geological Survey Open-File Report
96-364. Problem fixed for IBS package. Although
subsidence is only meant to be active for layers in which
IBQ>0, sometimes MODFLOW performed subsidence
calculations when IBQ<0. Note that this was a problem
only if negative IBQ values were specified. That is, the
code has always worked correctly for IBQ=0 and IBQ>0.
MODFLOW-88 Version 2.5 1995/06/23 - Added direct solution package
(DE45).
MODFLOW-88 Version 2.4 1995/06/15 - Added transient leakage package
(TLK1).
MODFLOW-88 Version 93/08/30 - Release with PCG2, BCF3, STR1, HFB1,
ISB1, CHD1, and GFD1 additions.
MODFLOW-88 Version 87/07/24 - Fortran 77 version published in U.S.
Geological Survey Techniques of Water-Resources
Investigations 6-A1.
MODFLOW Version 83/12/28 - Fortran 66 version published in U.S.
Geological Survey Open-File Report 83-875.
DATA REQUIREMENTS
In order to use MODFLOW, initial conditions, hydraulic
properties, and stresses must be specified for every model
cell in the finite-difference grid.
OUTPUT OPTIONS
Primary output is head, which can be written to the listing
file or into a separate file. Other output includes the
complete listing of all input data, drawdown, and budget
data. Budget data are printed as a summary in the listing
file, and detailed budget data for all model cells can be
written into a separate file.
SYSTEM REQUIREMENTS
MODFLOW-2000 generally is written in Fortran 77 with the
following extensions: use of variable names longer than 6
characters, Fortran 90 statements for dynamic memory
allocation, a call to SUBROUTINE GETARG to retrieve command-
line arguments, and two calls to DATE_AND_TIME, which is a
Fortran 90 intrinsic subroutine. 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 and 4 mb of
memory.
Starting with version 1.12, a Fortran-90 or later compiler
is required to compile one or more of the source-code files,
including gwf1sub1.f.
PROCESSES
This version of MODFLOW includes the following processes:
GWF1 -- Ground-Water Flow Process
SEN1 -- Sensitivity Process
OBS1 -- Observation Process
PES1 -- Parameter-Estimation Process
PACKAGES
This version of MODFLOW includes the following packages:
BAS6 -- Basic Package
BCF6 -- Block-Centered Flow Package
LPF1 -- Layer-Property Flow Package
RIV6 -- River Package
DRN6 -- Drain Package
WEL6 -- Well Package
GHB6 -- General Head Boundary Package
RCH6 -- Recharge Package
EVT6 -- Evapotranspiration Package
CHD6 -- Time-Variant Specified-Head Package
HFB6 -- Horizontal Flow Barrier Package
SIP5 -- Strongly Implicit Procedure Package
SOR5 -- Slice Successive Over-Relaxation Package
PCG2 -- Version 2 of Preconditioned Conjugate Gradient
Package
DE45 -- Direct solver
LMG1 -- Multigrid solver (for USGS use only)
STR6 -- Streamflow-Routing Package
ADV2 -- Advective-Transport Observation Package
RES1 -- Reservoir Package (RES is the file type in the
MODFLOW name file)
FHB1 -- Flow and Head Boundary Package (FHB is the file
type in the MODFLOW name file)
IBS6 -- Interbed Storage (subsidence) Package (IBS is the
file type in the name file)
HUF2 -- Hydrogeologic-Unit Flow Package
LAK3 -- Lake Package
ETS1 -- Evapotranspiration with a Segmented Function Package
DRT1 -- Drains with Return Flow Package
LMT6 -- Link to MT3DMS contaminant-transport model
MNW1 -- Multi-Node Well Package
DAF1 -- Diffusion Analogy Surface-Water Flow Package
SUB1 -- Subsidence and Aquifer-System Compaction Package
SFR2 -- Stream-Flow Routing Package, version 2
GMG1 -- Geometric MultiGrid Solver Package
SWT1 -- Subsidence and Aquifer-System Compaction Package
for Water-Table Aquifers
ADDITIONAL CAPABILITIES:
HYDMOD -- Hydrograph option
GAGE -- Hydrograph option for lakes (LAK3 Package) and streams
(SFR Package)
DOCUMENTATION
The basic documentation is contained in the following five
reports:
Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000,
MODFLOW-2000, the U.S. Geological Survey modular ground-water model --
User guide to modularization concepts and the Ground-Water Flow
Process: U.S. Geological Survey Open-File Report 00-92, 121 p.
Hill, M.C., Banta, E.R., Harbaugh, A.W., and Anderman, E.R., 2000,
MODFLOW-2000, the U.S. Geological Survey modular ground-water model --
User guide to the Observation, Sensitivity, and Parameter-Estimation
Processes and three post-processing programs: U.S. Geological Survey
Open-File Report 00-184, 210 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.
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.
The BCF6 code is documented in several places. It includes
the capabilities of BCF1, BCF2, and BCF3 Packages. The
primary documentation is in the basic model documentation
(TWRI 6-A1, OFR 96-485, and OFR 96-486).
BCF2 documentation describes the addition of the capability
to convert dry cells to wet:
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.
BCF3 documentation describes the addition of alternate
interblock transmissivities.
Goode, D.J., and Appel, C.E., 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.
Version 2 of Preconditioned Conjugate Gradient Package is
documented in:
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.
The Streamflow-Routing (STR) Package is documented in:
Prudic, D.E., 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.
The Time-Variant Specified-Head Package is documented in:
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: U.S. Geological Survey Techniques of Water-
Resources Investigations, book 6, chap. A2, 68 p.
The Horizontal-Flow Barrier Package is documented in:
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.
The DE45 Package is documented in:
Harbaugh, A.W., 1995, Direct solution package based on
alternating diagonal ordering for the U.S. Geological
Survey modular finite-difference ground-water flow model:
U.S. Geological Survey Open-File Report 95-288, 46 p.
The RES1 Package is documented in:
Fenske, J.P., Leake, S.A., and Prudic, D.E., 1996,
Documentation of a computer program (RES1) to simulate
leakage from reservoirs using the modular finite-
difference ground-water flow model (MODFLOW): U.S.
Geological Survey Open-File Report 96-364, 51 p.
The FHB1 Package is documented in:
Leake, S.A., and Lilly, M.R., 1997, Documentation of a
computer program (FHB1) for assignment of transient
specified-flow and specified-head boundaries in
applications of the modular finite- difference ground-
water flow model (MODFLOW): U.S. Geological Survey Open-
File Report 97-571, 50 p.
The ADV Package is documented in:
Anderman, E.R. and Hill, M.C., 1997, Advective-transport
observation (ADV) package, a computer program for adding
advective-transport observations of steady-state flow
fields to the three-dimensional ground-water flow
parameter-estimation model MODFLOWP: U.S. Geological
Survey Open-File Report 97-14, 67 p.
Anderman, E.R. and Hill, M.C., 2001, MODFLOW-2000, the U.S.
Geological Survey modular ground-water model -- Documentation
of the Advective-Transport Observation (ADV2) Package,
version 2: U.S. Geological Survey Open-File Report 01-54,
69 p.
File MODPATH-ADV_compatibility_3-2006.pdf, which is included
in the doc directory of the MODFLOW-2000 distribution.
HYDMOD is documented in:
Hanson, R.T. and Leake, S.A., 1999, Documentation of HYDMOD,
a program for extracting and processing time-series data
from the U.S. Geological Survey's modular three-dimensional
finite-difference ground-water flow model: U.S. Geological
Survey Open-File Report 98-564, 57 p.
The IBS Package is documented in:
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: U.S.
Geological Survey Techniques of Water-Resources
Investigations, Book 6, Chapter A2, 68 p.
The HUF Package is documented in:
Anderman, E.R., and Hill, M.C., 2000, MODFLOW-2000, the U.S.
Geological Survey modular ground-water model -- Documentation
of the Hydrogeologic-Unit Flow (HUF) Package: U.S. Geological
Survey Open-File Report 00-342, 89 p.
Anderman, E.R., Kipp, K.L., Hill, M.C., Valstar, Johan, and
Neupauer, R.M., 2002, MODFLOW-2000, the U.S. Geological Survey
modular ground-water model -- Documentation of the Model-Layer
Variable-Direction Horizontal Anisotropy (LVDA) capability of
the Hydrogeologic-Unit Flow (HUF) Package: U.S. Geological
Survey Open-File Report 02-409, 60 p.
Anderman, E.R., and Hill, M.C., 2003, MODFLOW-2000, the U.S.
Geological Survey modular ground-water model -- Three additions
to the Hydrogeologic-Unit Flow (HUF) Package: Alternative storage
for the uppermost active cells, Flows in hydrogeologic units, and
the Hydraulic-coductivity depth-dependence (KDEP) capability:
U.S. Geological Survey Open-File Report 03-347, 36 p.
The LAK Package is documented in:
Merritt, L.M. and Konikow, L.F., 2000, Documentation of a
computer program to simulate lake-aquifer interaction using
the MODFLOW ground-water flow model and the MOC3D
solute-transport model: U.S. Geological Survey Water-Resources
Investigations Report 00-4167, 146 p.
The ETS and DRT Packages are documented in:
Banta, E.R., 2000, MODFLOW-2000, the U.S. Geological Survey
modular ground-water model -- Documentation of packages for
simulating evapotranspiration with a segmented function (ETS1)
and drains with return flow (DRT1): U.S. Geological Survey
Open-File Report 00-466, 127 p.
The LMG Package is documented in:
Mehl, S.E. and Hill, M.C., MODFLOW-2000, the U.S. Geological
Survey modular ground-water model -- User guide to the LINK-AMG
(LMG) Package for solving matrix equations using an algebraic
multigrid solver: U.S. Geological Survey Open-File Report 01-177,
33 p.
The LMT Package is documented in:
Zheng, Chunmiao, Hill, M.C., and Hsieh, P.A., 2001, MODFLOW-2000,
the U.S. Geological Survey modular ground-water model - User
guide to the LMT6 package, the linkage with MT3DMS for multi-
species mass transport modeling: U.S. Geological Survey Open-File
Report 01-82, 43 p.
The MNW Package is documented in:
Halford, K.J. and Hanson, R.T., 2002, User guide for the drawdown-
limited, multi-node well (MNW) package for the U.S. Geological
Survey's modular three-dimensional finite-difference ground-water
flow model, versions MODFLOW-96 and MODFLOW-2000: U.S. Geological
Survey Open-File Report 02-293, 33 p.
The DAF Package is documented in:
Jobson, H.E. and Harbaugh, A.W., 1999, Modifications to the
diffusion analogy surface-water flow model (DAFLOW) for coupling
to the moddular finite-difference ground-water flow model (MODFLOW):
U.S. Geological Survey Open-File Report 99-217, 107 p.
The SUB Package is documented in:
Hoffmann, J., Leake, S.A., Galloway, D.L., and Wilson, A.M., 2003,
MODFLOW-2000 Ground-Water Model--User Guide to the Subsidence and
Aquifer-System Compaction (SUB) Package: U.S. Geological Survey
Open-File Report 03-233, 44 p.
The SFR Package is documented in:
Prudic, D.E., Konikow, L.F., and Banta, E.R., 2004, A new stream-
flow routing (SFR1) package to simulate stream-aquifer interaction
with MODFLOW-2000: U.S. Geological Survey Open-File Report
2004-1042, 95 p.
Niswonger, R.G. and Prudic, D.E., 2005, Documentation of the
Streamflow-Routing (SFR2) Package to include unsaturated flow
beneath streams--A modification to SFR1: U.S. Geological Survey
Techniques and Methods, Book 6, Chap. A13, 47 p.
The GMG Package is documented in:
Wilson, J.D. and Naff, R.L., 2004, The U.S. Geological Survey modular
ground-water model -- GMG linear equation solver package
documentation: U.S. Geological Survey Open-File Report 2004-1261,
47 p.
The SWT Package is documented in:
Leake, S.A., and Galloway, D.L., 2007, MODFLOW ground-water model --
User guide to the Subsidence and Aquifer-System Compaction Package
(SUB-WT) for Water-Table Aquifers: U.S. Geological Survey Techniques
and Methods, Book 6, Chap. A23, 42 p.
CONTACTS
Operation:
U.S. Geological Survey
Office of Ground Water
Arlen Harbaugh
411 National Center
Reston, VA 20192
harbaugh@usgs.gov
The USGS MODFLOW fact sheet (a short description of the MODFLOW
model) can be retrieved using the World-Wide Web at site:
http://water.usgs.gov/public/pubs/FS/FS-121-97/
See
http://water.usgs.gov/software/ordering_documentation.html
for information on ordering printed copies of USGS publications.
SEE ALSO
modpath(1) - Particle-tracking postprocessor program for the
modular three-dimensional finite-difference
ground-water flow model
zonebudget(1) -- Program for computing subregional water budgets
for MODFLOW ground-water flow models