With One-Third of Largest Aquifers Highly Stressed, It’s Time to Explore and Assess the Planet’s Groundwater

NASA's twin-satellite mission known as GRACE has helped scientists estimate how much water is being depleted from the world's major aquifers, but there is great uncertainty about how much water these aquifers hold. Image courtesy of NASA.
NASA’s twin-satellite mission known as GRACE has helped scientists estimate how much water is being depleted from the world’s major aquifers, but there is great uncertainty about how much water these aquifers hold. Image courtesy of NASA.

Imagine if your bank statement arrived each month and told you how much money you had withdrawn and deposited, but told you nothing about how much money you had at the beginning or end of the month.

You’d know whether your balance had grown or shrunk, but you’d have no idea whether you could afford to buy a new house, take a vacation, or make it through that last year of college without bussing tables on the weekends.

This is pretty much the state we’re in with the world’s groundwater accounts, which supply 2 billion people with drinking water and irrigate a large share of the world’s food.

“[I]n most cases, we do not know how much groundwater exists in storage,” write the authors of a study published last month in Water Resources Research (WRR), a journal of the American Geophysical Union.

As a result, we’re clueless about how long we can keep drawing down these water reserves before they run out.

And we are indeed drawing many of them down.

One-third of the world’s 37 largest aquifers are highly stressed to over-stressed, according to a companion study published in the same issue of WRR. The eight most highly stressed aquifers receive almost no natural recharge to offset human use – including aquifers in Saudi Arabia, northwestern India and Pakistan.

Scientists at the University of California at Irvine led both studies, with doctoral student Alexandra Richey serving as lead author. Other team members came from NASA, the National Center for Atmospheric Research, National Taiwan University and UC Santa Barbara.

Satellites Help Measure Depletion

Thanks to a NASA satellite mission launched —> Read More

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