Underground water reservoirs are falling rapidly – 01/25/2024 – Environment

The world’s groundwater levels have shown a broad and accelerated decline over the last 40 years, according to a study published this Wednesday (24) in the scientific journal Nature. The drop in reservoirs was driven by unsustainable irrigation practices and climate change.

Groundwater is an important source of fresh water for farms, homes and industries. According to the article, the depletion of these reservoirs can pose severe economic and environmental threats that include crop failure and destructive land subsidence, especially in coastal areas.

According to UNESCO, groundwater represents almost 99% of the planet’s freshwater reserves.

“One of the main reasons behind the rapid and accelerating decline of groundwater is excessive withdrawal for irrigated agriculture in dry climates,” said Scott Jasechko of the University of California at Santa Barbara (USA), one of the study’s co-authors.

But drought, driven by climate change, has also had an impact. According to Jasechko, the lack of rain and excessive heat likely causes farmers to pump more groundwater to ensure their crops are irrigated.

Depletion has been especially pronounced in arid climates with extensive agricultural areas, according to the study, which analyzed 170,000 wells in more than 40 countries. Northern China, Iran and the western United States are among the most affected regions.

More than a third of the 1,693 aquifer systems — bodies of porous rock or sediment that hold groundwater — monitored by the study have fallen by at least 0.1 meter per year from 2000 to 2022, with 12% experiencing annual declines greater than 0.5 meter .

Some of the most affected aquifers in Spain, Iran, China and the United States saw a reduction of more than 2 m per year during the period.