Techniques and Methods 6–A23
A new computer program was developed to simulate vertical compaction in models of regional ground-water flow. The program simulates ground-water storage changes and compaction in discontinuous interbeds or in extensive confining units, accounting for stress-dependent changes in storage properties. The new program is a package for MODFLOW, the U.S. Geological Survey modular finite-difference ground-water flow model. Several features of the program make it useful for application in shallow, unconfined flow systems. Geostatic stress can be treated as a function of water-table elevation, and compaction is a function of computed changes in effective stress at the bottom of a model layer. Thickness of compressible sediments in an unconfined model layer can vary in proportion to saturated thickness.
Posted August 2007
Leake, S.A., and Galloway, D.L., 2007, MODFLOW ground-water model—User guide to the Subsidence and Aquifer-System Compaction Package (SUB-WT) for water-table aquifers: U.S. Geological Survey, Techniques and Methods 6–A23, 42 p.