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According to a study published on Wednesday (24) in the journal Nature, groundwater levels worldwide have declined sharply and at an accelerated rate over the past 40 years. The decline in reservoirs has been caused by unsustainable irrigation practices and climate change.
Groundwater is an important source of fresh water for farms, households and industries. According to the article, the depletion of these reservoirs could pose serious economic and environmental threats, including crop failures and destructive land subsidence, particularly in coastal areas.
According to UNESCO, groundwater accounts for almost 99% of the Earth's freshwater reserves.
“One of the main reasons for the rapid and accelerating decline of groundwater is excessive withdrawal for irrigated agriculture in arid climates,” said Scott Jasechko of the University of California, Santa Barbara, USA, one of the study's coauthors.
But the drought caused by climate change also has an impact. According to Jasechko, the lack of rain and excessive heat are likely causing farmers to pump more groundwater to ensure irrigation for their crops.
According to the study, which analyzed 170,000 wells in more than 40 countries, depletion was particularly pronounced in dry climates with extensive agricultural land. Northern China, Iran and the western United States are among the hardest hit regions.
More than a third of the 1,693 aquifer systems monitored by the study bodies of porous rock or sediment that store groundwater fell at least 0.1 meters per year between 2000 and 2022, with 12% annual declines of more than 0.5 meters recorded.
Some of the most affected aquifers in Spain, Iran, China and the United States recorded declines of more than 2 m per year during this period.