Groundwater Pumping Causing San Joaquin Valley to Sink Faster than Ever, NASA Says

posted: 08/20/15
by: Danny Clemens
land subsidence

Extensive groundwater pumping in California is causing land in the San Joaquin Valley to sink at record rates, according to a new report from NASA.

The report, commissioned by the California Department of Water Resources, reveals that some areas of the valley are sinking nearly 2 inches each month, a phenomenon known as land subsidence. According to the United States Geological Survey, land subsidence can have detrimental impacts over long periods of time.

"When the water is withdrawn, the rocks falls in on itself," the agency explains on its website. "Throughout Mexico City [...] long-term extraction of groundwater has caused significant land subsidence and associated aquifer-system compaction, which has damaged colonial-era buildings, buckled highways, and disrupted water supply and waste-water drainage. Some buildings have been deemed unsafe and have been closed and many others have needed repair to keep them intact."

In California's case, the excessive groundwater removal has been prompted by extreme drought conditions, which have been wreaking havoc on the region for five years.

"Groundwater acts as a savings account to provide supplies during drought, but the NASA report shows the consequences of excessive withdrawals as we head into the fifth year of historic drought," CDWR Director Mark Cowin remarked in a news release.

"We will work together with counties, local water districts, and affected communities to identify ways to slow the rate of subsidence and protect vital infrastructure such as canals, pumping stations, bridges and wells."

NASA researchers analyzed years of images and data collected by agency aircraft and American, Japanese and Canadian satellites to determine how fast land is sinking. The agency also plans to analyze information from the European Space Agency's Sentinel-1 mission to better understand land subsidence on a broader scale.

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