MODFLOW-2000, The U.S. Geological Survey modular ground-water model: User guide to modularization concepts and the ground-water flow process

This report describes an enhanced version of the U.S. Geological Survey modular ground-water model, called MODFLOW-2000, for which the structure has been expanded to facilitate the solution of multiple related equations. The performance of the program has been tested in a variety of applications. Future applications, however, might reveal errors that were not detected in the test simulations. Users are requested to notify the U.S.