MODFLOWP
Category Parameter estimation
Platform DOS
Status Public domain
Description MODFLOWP is a parameter estimation package that can be used in conjunction with MODFLOW to improve model construction and calibration. It is an extension of the USGS modular three-dimensional, finite-difference ground-water flow model (MODFLOW), that includes the Parameter-Estimation Package using nonlinear regression. It functions nearly identically to MODFLOW when the Parameter-Estimation Package is not used. Parameters are estimated by minimizing a weighted least-squares objective function by the modified GaussNewton method or by a conjugate-direction method. Parameters used to calculate the following MODFLOW model inputs can be estimated: transmissivity and storage coefficient of confined layers; hydraulic conductivity and specific yield of unconfined layers; vertical leakance; vertical anisotropy (used to calculate vertical leakance); horizontal anisotropy; hydraulic conductance of the River, Streamflow-Routing, General Head Boundary, and Drain Packages; areal recharge rates; maximum evapotranspiration; pumping rates; and the hydraulic head at constant-head boundaries. 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 or 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.
Cost Free on www
Data formats supported None stated
Supplier in United States of America  International Ground Water Modeling Center 

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