
Scheda modello
MODFLOW: A Modular Three Dimensional FiniteDifference Ground
Water Flow Model
MODFLOW is a 3D, cellcentered, finite difference, saturated flow
model developed by the United States Geological Survey.
It can perform both steady state and transient
analyses and has a wide variety of boundary conditions and input
options.
MODFLOW is divided into a series of components called "packages."
Each package performs a specific task. Some of the packages are
always required for a simulation and some are optional. The input
for each package is contained in a separate text file.
The block centered flow package performs the cell by cell flow
calculations withthe capability to rewet dry cells. The river
package is used to simulate river type boundary conditions. The
recharge package simulates recharge to the groundwater from precipitation.
The well package is used to simulate well type boundary conditions,
the drain package to simulate drain type boundary conditions,
the evapotranspiration package to simulate the effect of evapotranspiration
in the vadose zone. The general head boundary package is used
to simulate head type boundary conditions where the value of the
boundary condition depends on the head in the cell and it is commonly
used to simulate lakes.
The packages used for the computation are: the Strongly Implicit
Procedure Package package, which is an iterative solver based
on the strongly implicit procedure, the Preconditioned Conjugate
Gradient Package package, an iterative solver based on the preconditioned
conjugate gradient technique, and the Slice Successive Overrelaxation
Package package, another iterative solver based on the slice successive
overrelaxation technique.
KEYWORDS
area: 
ground water

objectives: 
simulation

description: 
water flow, threedimensional domain, finite difference,
saturated media, stationary conditions, transient conditions

SOFTWARE AVAILABILITY
The program is available at:
IGWMC Europe
TNO Institute of Applied Geoscience
P.O. Box 012
2600 JA Delft, The Netherlands
Phone: +31.15.697215
FAX: +31.15.564800
Order Nø FOS 08 PC
or
Scientific Software Group
P.O. Box 23041
Washington D.C.
200263041
Phone: 703620.9214
Fax: 703620.6793
AUTHORS
M.G. Mc Donald and A.W. Harbaugh
U.S. Geological Survey
REFERENCES
 Michael G. McDonald and Arlen W. Harbaugh, A MODULAR THREE
DIMENSIONAL FINITEDIFFERENCE GROUNDWATER FLOW MODEL, Book 6
Chapter A1 of "Techniques of Water Resources" investigation
of the united States Geological Survey, U.S. Government Printing
Office, 1988.
 McDonald, M.G. and Harbaugh, A.W., 1988, A modular threedimensional
finitedifference groundwater flow model: U.S. Geological Survey
Techniques of WaterResources Investigations Book 6,Chapter A1,
586 p.
 Hill, M.C., 1990, Preconditioned conjugategradient 2 (PCG2),
a computer program for solving groundwater flow equations: U.S.
Geological Survey WaterResources Investigations Report 904048,
43 p.
 Prudic, D.E., 1989, Documentation of a computer program to
simulate streamaquifer relations using a modular, finitedifference,
groundwater flow model: U.S. Geological Survey OpenFile Report
88729, 113 p.
 Leake, S.A. and Prudic, D.E., 1988 Documentation of a computer
program to simulate aquifersystem compaction using the modular
finitedifference groundwater flow model: U.S. Geological Survey
OpenFile Report 88482, 80 p.
 Harbaugh, A.W., 1992, A generalized finitedifference formulation
for the U.S. Geological Survey modular threedimensional finitedifference
groundwater flow model: U.S. Geological Survey OpenFile Report
91494, 60 p.
 McDonald, M.G., Harbaugh, A.W., Orr, B.R., and Ackerman, D.J.,
1992, A method of converting noflow cells to variablehead cells
for the U.S. Geological Survey modular finitedifference groundwater
flow model: U.S. Geological Survey OpenFile Report 91536, 99
p.
 Goode, D.J. and Appel, C.A., 1992, Finitedifference interblock
transmissivity for unconfined aquifers and for aquifers having
smoothly varying transmissivity: U.S. Geological Survey Water
Resources Investigations Report 924124, 79 p.
 Hsieh, P.A. and Freckleton, J.R., 1993, Documentation of a
computer program to simulate horizontalflow barriers using the
U.S. Geological Survey modular threedimensional finitedifference
groundwater flow model: U.S. Geological Survey OpenFile Report
92477, 32 p.
 Leake, S.A., Leahy, P. Patrick, and Navoy, Anthony, S., 1994,
Documentation of a computer program to simulate transient leakage
from confining units using the modular finitedifference groundwater
flow model: U.S.Geological Survey OpenFile Report 9459, 70 p.
