Recently published satellite data reveal rapid subsidence (i.e. sinking) of land in California’s Central Valley that spans more than 1,200 square miles, says E&E Publishing, which covers environmental policy and markets. The culprit is the pumping of groundwater for agricultural and urban uses, which occurred amid persistent drought and surface-water restrictions. In places, subsidence occurred at a rate of nearly 1' per year during 2008 to 2010, the period covered in the U.S. Geological Survey report. Canal flows have been reduced, and structural damages have cost millions.
To measure elevation change in California’s Central Valley, researchers used a satellite-based system that measures ground-surface deformation.