Skip to main content
USGS - science for a changing world

USGS Land Subsidence Studies in California

Approximate location of maximum subsidence in the United States identified by research efforts of Dr. Joseph F. Poland (USGS; pictured). Signs on pole show approximate altitude of land surface in 1925, 1955, and 1977. The site is in the San Joaquin Valley southwest of Mendota, California.

Approximate location of maximum subsidence in the U.S., identified by research efforts of Dr. Joseph F. Poland (USGS; pictured). Signs on pole show approximate altitude of land surface in 1925, 1955, and 1977. The site is in the San Joaquin Valley southwest of Mendota, CA.

The USGS has conducted subsidence studies in California since the 1950s. Today, subsidence studies carried out by the USGS California Water Science Center integrate a suite of space-based (for example, InSAR, GPS) and ground-based (for example, extensometers) high-frequency measurements by using statistical and simulation modeling techniques. This produces high-quality scientific information about subsidence status and trends. Results of USGS Land Subsidence Studies help California water managers assess and track the state of water resources in their area and across the State. It also helps them assess the effectiveness of management strategies aimed at achieving sustainable groundwater and surface-water management goals.

San Joaquin Valley

Subsidence has been a major concern in the Central Valley since the 1950s. With agriculture and growing populations putting increased demands on the Valley's groundwater supply, subsidence must be monitored closely.

Coachella Valley

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.

Mojave Desert

Land subsidence has been ongoing in the dry lake beds throughout the Mojave and Morongo groundwater basins since the 1960s. In a study conducted from 2004 - 2009, continuous GPS stations were added to interferometric synthetic aperture radar (InSAR) methods to measure changes in land surface altitude.

Sacramento-San Joaquin Delta

Once covered by vast wetlands, the Delta is now a highly productive agricultural region and the hub of California's freshwater-delivery system. But draining of the historical wetlands exposed their thick peat soils to air. This caused the peat to decompose. Land surfaces across much of the Delta have subsided below sea level as a result, leaving them highly vulnerable to flooding and associated flood damages due to levee failure. Delta flooding can also interfere with freshwater deliveries to the southern part of the State.

Santa Clara Valley

The northern Santa Clara Valley was the first area in the United States where land subsidence due to groundwater overdraft was recognized and described. It is also the first area where remedial action effectively halted the subsidence.