World Largest Groundwater Aquifers Is Drying Out

The world’s largest underground aquifers – a source of fresh water for hundreds of millions of people — are being depleted at alarming rates, according to new NASA satellite data that provides the most detailed picture yet of vital water reserves hidden under the earth’s surface

According to a new study by Earth scientists at the University of California, Irvine, more than a third of the world's biggest groundwater basins are under distress. But while measurement trends suggests growing human consumption is depleting some of the world's largest aquifers, scientists say estimates about how much potable water remains are hard to come by.

The fact that the majority of the world's groundwater accounts “are past sustainability tipping points” was not known before, according to James Famiglietti, an author of both studies and a professor of Earth system science at the University of California, Irvine and senior water scientist at NASA's Jet Propulsion Laboratory.

Both studies appear Tuesday in the journal Water Resources Research. Famiglietti and his coauthors call for a global effort to determine how much water is left in the world's most important aquifers.
“The message we want to get out there is this is really unacceptable,” he said. “We really better get on some kind of major exploration program.”

“What I am afraid of is people will say, 'oh, we don’t know how much water there is, and maybe we have a ton,'” he said — but maybe we don't. “The signs of stress are all there.”

Perhaps not surprisingly, the worst-off aquifers are in the world’s driest areas, which draw heavily on underground water because of a lack of reliable surface water. Water flows in the Arabian Aquifer System, of the Middle East, and in the Murzuk-Djado Basin, of North Africa, were ranked as the two most distressed water basins. California's Central Valley, while not one of the eight overstressed basins, is America's most damaged aquifer.

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