A key water source for the world has been significantly depleted over the last decade, according to new data.
The Washington Post reported that 21 of the world’s 37 largest underground aquifers have passed their sustainability tipping points. Researchers pointed to satellite data from NASA, which has been tracking the aquifers for the last ten years. Two separate studies documenting this phenomenon were published in the Water Resources Research journal.
“The situation is quite critical,” Jay Famiglietti, senior water scientist of NASA’s Jet Propulsion Laboratory in California and principal investigator of the University of California Irvine-led studies, told The Post. Underground aquifers supply water for 35 percent of the world’s population. One staggering figure is in California, which is tapping into 60 percent of its aquifers, up from its usual 40 percent. Some scientists speculate the Golden State aquifers could run dry by the end of the year.
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The Post points out that the most endangered aquifers are in densely populated areas including northwest India, Pakistan, and North Africa. It is worth noting that the satellites could not measure the capacity of the aquifers, however. The abstract of the article titled “Quantifying Renewable Stress with GRACE” gives further background:
We find that the current state of knowledge of large-scale groundwater storage has uncertainty ranges across orders of magnitude that severely limit the characterization of resilience in the study aquifers. Additionally, we show that groundwater availability, traditionally defined as recharge and re-defined in this study as total storage, can alter the systems that are considered to be stressed versus unstressed.
We find that remote sensing observations from NASA’s Gravity Recovery and Climate Experiment (GRACE) can assist in providing such information at the scale of a whole aquifer. For example, we demonstrate that a groundwater depletion rate in the Northwest Sahara Aquifer System of 2.69 ± 0.8 km3 per year would result in the aquifer being depleted to 90% of its total storage in as few as 50 years given an initial storage estimate of 70 km3.
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