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WASHINGTON — The groundwater that supplies farms, homes, industry and cities is depleting around the world, and in many places faster than in the past 40 years, prompting new calls for urgent action to address the depletion. revealed in research.
The decline was most pronounced in arid regions with large areas of farmland, said the researchers, whose findings were published in the journal Nature on Wednesday. On the positive side, the researchers found several examples of aquifers where changes in policy and water management were helped to recover.
“Our study is a story of bad news and good news,” said Scott Jasechko, a water resources professor at the University of California, Santa Barbara, and lead author of the study. “The novelty of this study lies in its global scope.”
Groundwater is one of the world’s largest sources of fresh water, and aquifer depletion is a serious concern. Over-pumping aquifers can cause land to cave in or wells to run dry, threatening water resources for housing developments and farms used to irrigate fields.
Yasechko and colleagues analyzed groundwater data from 170,000 wells and about 1,700 aquifers in more than 40 countries, covering 75% of all groundwater withdrawals. For about a third of the mapped aquifers, we were able to analyze groundwater trends since this century and compare them to levels in the 1980s and 1990s.
This provides a more robust global picture of groundwater supplies and how farms, and to a lesser extent cities and industry, are straining that resource almost everywhere. Researchers and other experts also commented that governments are not taking sufficient steps to regulate groundwater in most or most parts of the world.
“That’s the bottom line,” said Upmanu Lal, a professor of environmental engineering at Columbia University and director of the Columbia Water Center, who was not involved in the study. “Groundwater depletion continues in most parts of the world.”
For about a third of the 542 aquifers for which researchers were able to analyze decades of data, they found that declines in the 21st century were more severe than in the previous two decades of the previous century. In most cases, the researchers found, it happened even in places where rainfall decreased over time. Aquifers in arid regions with large agricultural industries, such as northern Mexico, parts of Iran, and southern California, are particularly vulnerable to rapid groundwater depletion, the study found.
But there are some cases of hope, Yasechko said.
That’s because the authors found that in about 20% of the aquifers they studied, groundwater levels are declining at a slower rate in the 21st century than in the 1980s and 1990s.
“Our analysis suggests that long-term groundwater loss is neither universal nor irreversible,” the authors write. However, one of them, Richard Taylor, a professor of hydrogeology at University College London, said in a subsequent interview that pumping too much groundwater could lead to land subsidence and subsidence, irreversibly damaging aquifers. He said that there is a possibility that the aquifer will not be able to store water.
In Saudi Arabia, researchers have found that groundwater depletion in the East Sak aquifer has slowed since the turn of the century. Perhaps this is an effect of changes in agricultural practices that the desert kingdom has implemented in recent decades to limit water, such as banning the cultivation of some water-intensive crops. use.
Thailand’s Bangkok Basin is another example where research has highlighted that groundwater levels have risen in the early 21st century compared to previous decades. The authors cite groundwater pumping fees and licenses established by the Thai government as reasons for the improvements.
In a suburb of Tucson, Arizona, he cited a groundwater recharge project that stores surface water from the Colorado River underground as another example of a significant rise in groundwater levels in the 21st century.
“It means there is an ability to act, but it also means there are lessons to be learned,” Taylor said.
Hydrologists, policy makers, and other water experts often refer to groundwater as locally or sublocally because there are significant differences in how water moves through the rocks and soils of individual aquifers. It is often described as a resource.
“We can’t extrapolate from one region to another, but we can clearly map the fact that we’re depleting water faster than we’re accumulating it,” said former top water official in California. said Felicia Marcus, a research fellow at Stanford University’s School of Water Sciences. West Program, which was not involved in the study.
That means “you have to intervene,” Marcus said.
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The Associated Press receives support for coverage of water and environmental policy from the Walton Family Foundation. AP is solely responsible for all content. For all of AP’s environment coverage, visit https://apnews.com/hub/climate-and-environment.
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