Land Subsidence in the Coachella Valley

Science Center Objects

Groundwater is an important water-supply source in the Coachella Valley. The demand for water has exceeded the deliveries of imported surface water, and groundwater levels have been declining as a result of increased pumping. A network of GPS stations has been set up in the valley to monitor subsidence resulting from declining groundwater levels.

The Coachella Valley is about 65 miles long with an area of about 400 mi2 and includes the cities and communities of Palm Springs, Palm Desert, Indio, and Coachella. In the lower valley, groundwater has been an important source of agricultural, municipal, and domestic water supplies since the early 1920's. Pumping of groundwater resulted in water-level declines of as much as 50 ft between the early 1920's and the late 1940's before the importation of Colorado River water in 1949. As a result of the availability of this surface-water supply, pumping of groundwater was reduced, and water levels recovered throughout most of the valley during the 1950's through the 1970's. Since the 1970's, however, the demand for water has exceeded the deliveries of imported surface water, and groundwater levels have been declining again as a result of increased pumping.

The Coachella Valley Water District (CVWD) is responsible for effectively managing the water supply for a large part of the Coachella Valley. A successful management strategy involves reducing groundwater overdraft and related land subsidence while maintaining a reliable water supply to meet the growing demands of both agricultural and urban water users. As part of the overall water-management strategy, changes in land-surface elevation need to be monitored on a regular basis to assess whether and where land subsidence may be occurring. Continued monitoring has become even more important as allocations of Colorado River water change, complex water transfers are implemented, tiered rate structures are applied, and managed aquifer recharge measures are implemented.

In cooperation with the Coachella Valley Water District, the U.S. Geological Survey has established a program for monitoring land subsidence in the lower Coachella Valley. Data from the InSAR component of the monitoring program has been used with the data from the GPS surveys of the geodetic network, groundwater-level measurements, and groundwater production records, to map land-surface and groundwater-level changes and determine a possible relation between aquifer-system deformation and groundwater levels and(or) pumping. The InSAR data has also been used to expand the geodetic network into previously unmapped areas of deformation.

Map of the Coachella Valley shaded by the amount of subsidence as measured by InSAR.  GPS stations are included.

Areas of subsidence, consolidated rock, Global Positioning System (GPS) stations, and two Continuous GPS (CGPS) stations in the Coachella Valley, California, for June 27, 1995–September 19, 2010 (excludes November 8, 2000–November 30, 2003), as shown on a stacked and kriged interferogram. Three areas with larger magnitudes of subsidence are outlined. The Coachella Branch of the All-American Canal, which brings in water from the Colorado River, runs through an area of subsidence. (Public domain.)