GGSD Program Details for INVFD

INVFD

Category	Parameter estimation
Platform	DOS
Status	Public domain
Description	INVFD is a two-dimensional, steady-state ground-water flow model, which can be used to estimate parameters by nonlinear regression. The model simulates (leaky) confined flow in a heterogeneous aquifer. External boundary conditions include specified specific discharge normal to the boundary and specified hydraulic head. The model supports node-specific sources or sinks. Parameters are estimated by minimizing a weighted least-squares objective function by the modified Gauss-Newton method. The inverse model can estimate one or more of the following zoned parameters: transmissivity in X- and Y-direction (i.e., anisotropy), vertical leakance, and distributed recharge. The model requires independent information for the head distribution. The model uses an irregular rectangular grid of maximal 30 * 30 nodes. 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