Scientists Map Subsidence Levels in California
February 23, 2017
Using satellites, aircraft, and a complex tool known as interferometric synthetic aperture radar (InSAR), scientists have created a map of subsidence in California and released the results in a new report available via the Department of Water Resources. Subsidence is defined by the U.S. Geological Survey as a gradual settling or sudden sinking of the Earth’s surface owing to subsurface movement of earth materials. In California;s Central Valley, subsidence has been blamed on over-pumping from ground water aquifers.
The authors note that subsidence is a significant issue because “if water levels are drawn too low an irreversible compaction … occurs… The water cannot recharge the layers, causing permanent subsidence and loss of some groundwater storage capacity.” Thus, it is important to understand subsidence and its potential impacts on groundwater.
The report details the process of measurement and the results of the study. The research illustrates two “main subsidence bowls in the San Joaquin Valley” as well as some key pockets of intense subsidence that were newly detected. However, the authors do not identify methods to ameliorate the problem. Groundwater is a hot topic as the June 30 deadline to establish Groundwater Sustainability Agencies looms large.