Many parts of the world are experiencing a rapid reduction in groundwater that billions of people rely on for drinking, irrigation (灌溉) and other uses, according to new research that analyzed millions of groundwater level measurements from 170,000 wells in more than 40 countries.
It's the first study to show what's happening to groundwater levels at a global scale, according to the researchers involved, and will help scientists better understand what impact humans are having on this valuable underground resource, either through overuse or indirectly by changes in rainfall linked to climate change.
Groundwater, contained within cracks and pores in permeable bodies of rock known as aquifers (含水层), is a lifeline for people especially in parts of the world where rainfall and surface water are very little, such as northwest India and the southwest United States. Reduction in groundwater can make it harder for people to access freshwater to drink or to irrigate crops and can result in land subsidence (下沉).
The authors found that groundwater levels declined (下降) between 2000 and 2022 in 71% of the 1,693 aquifer systems included in the research, with groundwater levels declining more than 0.1 meter a year in 36%, or 617, of them. The Ascoy-Soplamo Aquifer in Spain had the fastest rate of decline in the data they collected — a median decline of 2.95 meters per year, said study coauthor Scott Jasechko, a professor at the Bren School of Environmental Science and Management at University of California Santa Barbara. Several aquifer systems in Iran were among those with the fastest rate of groundwater decline, he added.
The team wasn't able to gather data from much of Africa, South America and southeast Asia because of a lack of monitoring, but Jasechko said the study included the countries where most global groundwater pumping takes place.
