GROUNDWATER DEPLETION RATE ACCELERATING WORLDWIDE:

In recent decades, the rate at which humans worldwide are pumping dry the vast underground stores of water that billions depend on has more than doubled, say scientists who have conducted an unusual, global assessment of groundwater use. These fast-shrinking subterranean reservoirs are essential to daily life and agriculture in many regions, while also sustaining streams, wetlands, and ecosystems and resisting land subsidence and salt water intrusion into fresh water supplies.

Soaring global groundwater depletion bodes a potential disaster for an increasingly globalized agricultural system, says Marc Bierkens of Utrecht University in Utrecht, the Netherlands, and leader of the new study. “If you let the population grow by extending the irrigated areas using groundwater that is not being recharged, then you will run into a wall at a certain point in time, and you will have hunger and social unrest to go with it,” Bierkens warns. “That is something that you can see coming for miles.” He and his colleagues will soon publish their new findings in an upcoming issue of Geophysical Research Letters, a journal of the American Geophysical Union.

Groundwater represents about 30 percent of the total available fresh water on the planet, with surface water accounting for only one percent. The rest of the potable, agriculture friendly supply is locked up in glaciers or the polar ice caps. This means that any reduction in the availability of groundwater supplies could have profound effects for a growing human population.

The new assessment shows the highest rates of depletion in some of the world’s major agricultural centers, including northwest India, northeastern China, northeast Pakistan, California’s Central Valley, and the midwestern United States. “The rate of depletion increased almost linearly from the 1960s to the early 1990s,” says Bierkens. “But then you see a sharp increase which is related to the increase of upcoming economies and population numbers; mainly in India and China.” To see the full 23 September American Geophysical Union press release No. 10-30 go to: www.agu.org/news/press/pr_archives/2010/2010-30.shtml.