Monday, June 17, 2013

Satellites identify hotspots for drought in coming years

Sarah Fecht in Popular Mechanics: Despite heavy rains this week, drought persists throughout much of the Midwest and Southern U.S., forcing residents to pump more water from deep underground. Now a new paper in Science points out that our nation's groundwater reserves are also being depleted throughout large swaths of the U.S., partly because we're not doing a good job of keeping track of how much groundwater we're extracting versus how much gets replenished through precipitation.

"We don't really monitor water use," says James Famiglietti, an earth scientist at University of California, Irvine, and coauthor on the new paper. "It's crazy that we don't. It's like having a bank account and not keeping track of your deposits and withdrawals."

Famiglietti says NASA's Gravity Recovery and Climate Experiment (GRACE) satellites can help monitor groundwater on a global scale, and could even enhance flood and drought predictions. ...Using data from GRACE, Famiglietti's team has created a comprehensive map of groundwater levels across the United States, and it reinforces the identification of some troubling trends. For one, the northern U.S. is getting wetter over time, leading to increased risk from floods, and the southern U.S. is getting drier, leading to heightened risk of drought.

The map pinpoints six hotspots at high risk for water-related catastrophes: California's Central Valley, the Southern High Plains Aquifer in East Texas, and the areas around Houston, Alabama, and the mid-Atlantic states have all suffered steady groundwater depletion. Without proactive management, the authors say, aquifers in those regions could run dry within a few decades, putting the nation's food supply at risk. Meanwhile, water storage is increasing in the Missouri River Basin, making the region more prone to dangerous flooding.

"There's a picture that emerges from looking at these maps," Famiglietti says. "The subtext is that we have a national-scale problem that requires national-scale, coordinated, comprehensive water management . . . I don't think people realize the extent of the problem."...

This panoramic NASA view of east-central Texas on September 6, 2011, highlights numerous smoke plumes caused by wildfires burning across the state

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