Mary C. Hill

USGS-WRD

P.O. Box 25046, M.S. 413

Lakewood, CO 80225

Phone:

Fax : (303)236-5034

email: mchill@brrcrmail.cr.usgs.gov

R. Steven Regan

U.S. Geological Survey USGS-WRD

Hydrologic Analysis Software Support Tea

437 National Center

Reston, VA 20192

Phone:

Fax :

email: h2osoft@usgs.gov

This program is a new version of the U.S. Geological Survey modular, three-dimensional, finite-difference, ground-water flow model ( MODFLOW ), which, with the new Parameter-Estimation Package, can be used to estimate parameters by nonlinear regression. Parameters used to compute the following MODFLOW model inputs can be estimated: layer transmissivity, storage, coefficient of storage, hydraulic conductivity, and specific yield; vertical leakance; horizontal and vertical anisotropy; hydraulic conductance of the River, Streamflow- Routing, General-Head Boundary, and Drain Packages; areal recharge; maximum evapotranspiration; pumpage; and the hydraulic head at constant-head boundaries. Nearly any spatial variation in parameters can be defined by the user. Data used to estimate parameters can include existing independent estimates of parameter values, observed hydraulic heads or temporal changes in hydraulic heads, and observed gains and losses along head-dependent boundaries (such as streams). Model output includes statistics for analyzing the parameter estimates and the model; these statistics can be used to quantify the reliability of the resulting model, to suggest changes in model construction, and to compare results of models constructed in different ways.

**METHOD:**
Parameters are estimated by minimizing a weighted least-squares
objective function by the modified Gauss-Newton method or by a
conjugate-direction method.

**Hill, M.C., 1992,**A computer program (MODFLOWP) for estimating parameters of a transient, three-dimensional, ground-water flow model using nonlinear regression: U.S. Geological Survey Open-File Report 91-484, 358 p.**Hill, M.C., 1994,**Five computer programs for testing weighted residuals and calculating linear confidence and prediction intervals on results from the ground-water parameter-estimation program MODFLOWP: U.S. Geological Survey Open-File Report 93-481, 81 p.- readme.doc
- (Europe: readme.doc )

- USGS: Modflowp

- More information about groundwater modelling: R.B. Winston homepage

(Here you find also a version compiled for DOS-Computers)

Last review of this document by: 26.June 1997

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