MODFLOW Model
GMS includes a comprehensive graphical interface to the groundwater model MODFLOW 2000. MODFLOW is a 3D, cell-centered, finite difference, saturated flow model developed by the United States Geological Survey (McDonald & Harbaugh, 1988). MODFLOW can perform both steady state and transient analysis 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. The input for each package is generally contained in a separate file. Un updated list of the MODFLOW packages supported by GMS can be found at the GMS wiki.

To learn more about the MODFLOW model visit the following sites:
water.usgs.gov/...modflow
water.usgs.gov/...modflow2
For more detailed information on the MODFLOW model in GMS visit the GMS wiki at:
www.xmswiki.com/...MODFLOW