New & Noteworthy

 Ground-Water Availability in the United States (Circular 1323)

 CFP: Conduit Flow Process for MODFLOW-2005

 GSFLOW: A New Model for Simulation of Ground-Water and Surface-Water Interaction

 SEAWAT v4: Simulation of 3D Variable-Density Ground-Water Flow and Transport

USGS in Your State

USGS Water Science Centers are located in each state.

Land Subsidence

Some of the most spectacular examples of subsidence-related earth fissures occur in south-central Arizona. Photo from USGS Fact Sheet-165-00.

Land subsidence is a gradual settling or sudden sinking of the Earth's surface owing to subsurface movement of earth materials. Subsidence is a global problem and, in the United States, more than 17,000 square miles in 45 States, an area roughly the size of New Hampshire and Vermont combined, have been directly affected by subsidence.

The principal causes are aquifer-system compaction, drainage of organic soils, underground mining, hydrocompaction, natural compaction, sinkholes, and thawing permafrost. More than 80 percent of the identified subsidence in the Nation is a consequence of our exploitation of underground water, and the increasing development of land and water resources threatens to exacerbate existing land-subsidence problems and initiate new ones. In many areas of the arid Southwest, and in more humid areas underlain by soluble rocks such as limestone, gypsum, or salt, land subsidence is an often- overlooked environmental consequence of our land- and water- use practices.

Resources and Information on Subsidence:

• Land Subsidence in the United States (Fact Sheet 165-00) *
• Land Subsidence in the United States (circular 1182)
• Measuring Land Subsidence from Space (Fact Sheet-051-00)
• CIMDAS - Center For InSAR Monitoring
• Land Subsidence in California (web site)
• Land Subsidence From Ground-Water Pumping (web site)
• Estimates of hydraulic properties from a one-dimensional numerical model of vertical aquifer-system deformation, Lorenzi site, Las Vegas, Nevada (WRIR 03-4083)
• Detection and Measurement of Land Subsidence Using Global Positioning System and Interferometric Synthetic Aperture Radar, Coachella Valley, California, 1996-98 (WRIR 01-4193)
• Aquifer - System Compaction and Land Subsidence: Measurements, Analyses, and Simulations - the Holly Site, Edwards Air Force Base, Antelope Valley, California (WRIR 00-4015)
• USGS Subsidence Interest Group Conference Proceedings (1992, 1995, 2001)
  • Edwards Air Force Base, Antelope Valley, California, November 18-19, 1992: USGS OFR 94-532
  • Las Vegas, Nevada, February 14-16, 1995: USGS OFR 97-47
  • Galveston, Texas, November 27-29, 2001: USGS OFR 03-308
• Journal articles
  • The application of satellite differential SAR interferometry-derived ground displacements in hydrogeology: Hydrogeology Journal, v. 15, no. 1, pp. 133-154, (Galloway, D.L. and Hoffmann, J., 2007)
  • Seasonal subsidence and rebound in Las Vegas Valley, Nevada, observed by synthetic aperture radar interferometry: Water Resources Research, v. 37, no. 6, pp. 1551-1566, (Hoffmann, J., Zebker, H.A., Galloway, D.L., and Amelung, F., 2001)
• International Survey On Land Subsidence

* This report was initially printed with the report number "FS-087-00". The correct and current number for this report is "FS-165-00".