The world's essential aquifers are in deep crisis

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The water that flows from your tap, or that is unnecessarily packaged in single-use bottles, or that has helped grow produce in your fridge – all of it may have come from aquifers somewhere. These are layers of underground material that hold water, and may be composed of porous rock or sediments such as sand and gravel. When it rains, some of the water collects in lakes and rivers and eventually flows into the ocean, but some seeps deep into the ground and is stored in these underground reservoirs.

We dig shallow wells or drill deep boreholes to feed water into aquifers to hydrate our civilization, but that extraction is out of our hands. A shocking new paper was published today in the journal Nature looked at data available on 1,700 aquifer systems around the world and found that groundwater in 71 percent of them was declining. More than two-thirds of these aquifers are declining by 0.1 meters (0.33 ft) per year, while 12 percent are declining at a rate of 0.5 metres. (Think of this decline like looking down into a well, then coming back the next year and seeing that the water level is 0.1 meter lower.) About a third of the aquifer is experiencing ACCELERATED Scarcity, which means degradation is accelerating, especially where the climate is dry and there is a lot of agriculture that needs water.

“Real-world observations – 300 million of them in hundreds of thousands of wells around the world – show two main findings,” says UC Santa Barbara hydrologist Scott Jacechko, co-lead author of the new paper. “One is that rapid groundwater depletion is unfortunately widespread globally, especially in arid places where cropland is extensive. And then secondly, to make matters worse, groundwater depletion has, if anything, accelerated over the past four decades across a disproportionately large portion of the global landmass.”

Aquifers are considered reliable banks of water, safely locked underground where the liquid cannot easily evaporate. They are a rainy-day fund – or, more accurately, a dry-day fund – that is available to be used in times of need, such as during a drought. But from Chile to Afghanistan, India to China and back to the United States, humans are depleting these water reserves at an unsustainable pace. (In the maps below, darker red indicates a decline in groundwater of one meter per year, while lighter red indicates less decline.) In areas where already dry climates are becoming drier due to climate change, People have less groundwater to rely on. And hence they are forced to over-exploit the aquifers.

3D Earth model showing the eastern side of the globe with aquifer systems highlighted in red

Illustration: Scott Jaschekow/UCSB