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...The team was using satellite data from NASA's Gravity Recovery and Climate Experiment (GRACE) project, which measures the change in mass on the Earth below it. The project's primary goal was to track changes in ice sheets.
"GRACE is like a giant scale in the sky, it responds to gravity changes, the satellites are perturbed and they move around in their orbits due to changes in mass," said study co-author James Famiglietti, a hydrologist at the University of California, Irvine. The twin satellites take advantage of the fact that gravity's tug on a spot is proportional to its mass. And water is by far the heaviest thing that changes on Earth, so gravity changes can reveal how much water has been lost. [6 Weird Facts About Gravity]
Famiglietti and his colleagues found that the Tigris Euphrates Basin, which spans parts of Turkey, Syria, Iran and Iraq, lost an average of 16 million acre-feet (20 cubic kilometers) a year during the period of the study. By analyzing other data that tracked other water levels, such as the amount of snowmelt and reservoir levels in the region, the team concluded that most of the depletion came from pumping groundwater.
A drought during that time period may have depleted reservoirs and snowmelt, causing people to more aggressively pump groundwater, Famiglietti told LiveScience. The findings are even more worrisome, because climate change is projected to reduce rainfall in the region, causing even more water troubles, he said....
The Syrian Desert, shot by yeowatzup, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license
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