The world’s groundwater is disappearing like never before, but there is good news

“Water, water everywhere, and not a drop to drink.” So wrote Coleridge in 1834, unknowingly giving a pretty good description of planet Earth: so awash in water that our world looks blue from space, and yet only about 2.5 percent of it is actually drinkable – that is, sweet water.

Almost all of it consists of groundwater; 99 percent of all liquid fresh water is found in this form, hidden just below the Earth’s surface in cracks and pores of rock and sediment. It is a crucial resource for some 2.5 billion people today, providing drinking water and irrigating crops – and even generating energy and powering industries. So you’d think we’d keep an eye on how much we’re going through.

Instead, the world has been “wasting groundwater like there is no tomorrow,” Hansjörg Seybold, senior scientist at ETH Zurich’s Department of Environmental Systems Science, told SciTechDaily. He is co-author of a new study on global groundwater decline, published last month. The findings provide a sobering picture of humanity’s water consumption around the world.

Researchers “analyzed groundwater level measurements taken over the past two decades at 170,000 wells in approximately 1,700 aquifer systems,” Mohammad Shamsudduha, co-author of the paper and associate professor at the UCL Institute for Risk and Disaster Reduction, wrote in a blog. message about the research.

“This is the first study to map trends in groundwater levels using ground data on a global scale in such unprecedented detail that no computer model or satellite missions have achieved this yet.”

What they discovered was an unprecedented drop in global groundwater levels: a reduction of more than 10 centimeters (3.9 inches) per year in 36 percent – ​​more than one in three – of the aquifer systems sampled. In a third of Thatwater disappeared even faster – by more than 50 centimeters (19.7 in) per year in 12 percent of the total aquifers.

“We were not surprised that groundwater levels have fallen sharply worldwide,” Seybold told SciTechDaily, “but we were shocked by the way the pace has increased over the past two decades.”

The study covered more than 40 countries, but some stood out for their severity: for example, the West Qazvin Plain in Iran is drying out faster than before, as is the Lobo Plain in Texas. Areas like these are particularly vulnerable to groundwater depletion: populations are growing, natural conditions are arid, and the climate crisis is only making it hotter, drier and less predictable.

Even outside such desert climates, groundwater loss is bad news. “Continued depletion of groundwater could lead to seawater intrusion into coastal areas, land subsidence, stream depletion and drying up of wells,” Shamsudduha wrote. “Depletion of aquifers can have serious consequences for water and food security, and for the natural functioning of wetlands and rivers, and, most importantly, for access to clean and convenient freshwater for all.”

But there is good news. Among all these losses, there are also areas where groundwater reserves are showing a recovery – areas where the depletion of groundwater aquifers is slowing down or even reversing. Where strict regulations have been introduced to tackle water use, the effect has been particularly strong: for example, pumping costs and well licensing have increased groundwater reserves in Thailand’s Bangkok Basin, while losses in Iran’s Abbas-e Sharghi Basin have been reversed by the diversion of water from a large dam in the west of the country.

“Such examples are a ray of hope,” Scott Jasechko, a researcher at the University of California, Santa Barbara, and lead author of the paper, told SciTechNews. But they are far from guaranteed: “OncThe severely depleted aquifers in semi-deserts and deserts can take hundreds of years to recover because there is simply not enough rain to quickly replenish these aquifers.” he added.

The clock is ticking. If groundwater reserves become too low, entire ecosystems and economies can be threatened: land can subside, wells can dry up, and water salinization can permanently destroy the chances of farms and wildlife to thrive.

“That’s why we can’t put the problem on the back burner,” Seybold warned. “The world needs to take urgent action.”

“The round water level does not always have to go in one direction: downwards.”

The article was published in the journal Nature.

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