A new view of global groundwater reveals an urgent need to reverse depletion trends
From a very interesting blog contribution by Cynthia Barnett at ensia:
Analyzing data from twin satellites that detect water mass by measuring changes in Earth's gravity, scientists say the Middle East lost 117 million acre-feet of freshwater between 2003 and 2009 — nearly enough to fill the Dead Sea. The researchers attributed about one-fifth of the loss to dwindling snowpack and drying soils, the result of drought. Surface water decreases from lakes and reservoirs made up another fifth. But groundwater pulled the biggest vanishing act. Sixty percent of the loss was pumped up and out of the region's fragile aquifers, with irrigation the primary drain.
"We've never been able to see, this clearly, the widespread nature of groundwater depletion," says Jay Famiglietti, director of the University of California's Center for Hydrologic Modeling at UC Irvine and lead investigator on NASA's Gravity Recovery and Climate Experiment groundwater studies. Now in its 12th year of orbit, GRACE offers an unprecedented view of global aquifer storage and the movement of groundwater — least understood of all freshwater, and source of nearly half the irrigation and drinking water in the world.
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