"Since 2002, NASA's twin Gravity Recovery and Climate Experiment (GRACE) satellites have been monitoring large-scale groundwater depletion all over the globe. In northwest India, the Middle East, and also close to home in California's Central Valley aquifer, a significant fraction of the water needed to farm comes from groundwater. With GRACE, we have a tool that allows us to very accurately detect where and how much water is pumped from deep below -- unfortunately, often at unsustainable rates. For example, during the 2006 to 2010 California drought, the equivalent volume of an entire Lake Mead was extracted from the Central Valley Aquifer!"

Dr. Felix Landerer, GRACE-FO deputy project scientist

Groundwater is an indicator of climate variability and human impacts on the environment. Combining GRACE data with hydrologic modeling enables scientists and water managers to observe dynamic changes in groundwater over large regions or where well data are sparse. GRACE-FO will provide global measurements on seasonal and inter-annual river basin water storage changes, human influences on regional water storage changes, large-scale evapotranspiration, land-ocean mass exchange, and continental aquifer changes. GRACE data are currently being used to generate weekly drought indicators at the National Drought Mitigation Center.

Studies have found that a third of Earth’s largest groundwater basins are being rapidly depleted by human consumption, despite not having accurate data about how much water remains in them. That means significant segments of Earth’s population are consuming groundwater without knowing when it might run out, researchers found. Two studies led by the University of California, Irvine (UCI), used data from GRACE to comprehensively characterize global groundwater losses from space.

“Available physical and chemical measurements are simply insufficient,” said UCI professor and principal investigator Jay Famiglietti, who is also the senior water scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “Given how quickly we are consuming the world’s groundwater reserves, we need a coordinated global effort to determine how much is left.”

California drought as seen by GRACE.
NASA GRACE data shows land in much of California's Central Valley sinking from groundwater extraction.

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