A figure shows the global distribution of modern groundwater as a depth if it was extracted and pooled at the land surface like a flood. (Credit: Karyn Ho)
An international group of hydrologists produced the first data-driven estimate of Earth's total supply of groundwater. The study, led by Tom Gleeson of the University of Victoria with co-authors at the University of Texas at Austin, the University of Calgary and the University of Göttingen, was published in Nature Geoscience.
The report shows that less than 6 percent of groundwater in the upper two kilometers of Earth's landmass is renewable within a human lifetime.
This has never been known before, said Gleeson. We already know that water levels in lots of aquifers are dropping. We're using our groundwater resources too fast”faster than they're being renewed.
Using multiple datasets (including data from close to 1 million watersheds) and more than 40,000 groundwater models, the study estimates a total volume of nearly 23 million cubic kilometers of total groundwater, of which 0.35 million cubic kilometers is younger than 50 years old.
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