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Techniques and Methods 6–A23

A Product of the Ground-Water Resources Program
Prepared in Cooperation with the Central Arizona Water Conservation District

MODFLOW Ground-Water Model—User Guide to the Subsidence and Aquifer-System Compaction Package (SUB-WT) for Water-Table Aquifers

By S.A. Leake and D.L. Galloway

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T&M 6-A21
PDF (439 kB)


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.

Version 1.0

Posted August 2007

Suggested citation:

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.

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