February 28, 2003
The earth has subsided as much as 4 inches in parts of the Mojave Desert in southern California, according to U.S. Geological Survey scientists. Using the satellite mapping process known as interferometric synthetic aperture radar (InSAR), scientists have detected large earth surface depressions near the agricultural areas of Lucerne Valley, El Mirage, Lockhart and Newberry Springs in the southwestern portion of the Mojave Desert. The subsidence occurred between 1992 and 1999 and is linked to declining water levels.
“The magnitude of subsidence in some of the areas is significant,” said Michelle Sneed, USGS scientist. “The compaction of the aquifer systems in these areas may be permanent.”
A USGS study, conducted in cooperation with the Mojave Water Agency, found that land subsidence was linked to water-level declines of more than 100 feet between the 1950s and the 1990s. Land subsidence can disrupt surface drainage, reduce aquifer storage, cause earth fissures and damage wells, building, roads and utility infrastructure. “Earth fissures several feet wide and deep have been observed in Lucerne Valley,” Sneed said. The USGS reports that continued monitoring of some areas of the Mojave Desert is warranted because groundwater levels continue to decline, and pumping-induced land subsidence, documented by this study, likely will increase.
The USGS report, “Detection and Measurement of Land Subsidence Using Interferometric Synthetic Aperture Radar and Global Positioning System, San Bernardino County, Mojave Desert, California” may be found at http://water.usgs.gov/.