One-Fifth of Groundwater Wells Worldwide at Risk of Running Dry

The researchers analyzed data about 39 million wells and estimated that between 6 and 20% of the wells were at risk of drying if the water table dipped a few meters.

Groundwater cached below the Earth’s surface is one of the world’s most precious resources. Nearly half of the human population depends on these reserves for our daily needs and for agriculture. But up to a fifth of wells worldwide that tap into these reserves are at risk of running drying, a recent study in Science has found.

A related commentary published in the same journal called the new paper “a timely warning that universal access to groundwater is fundamentally at risk.”

The researchers analyzed 39 million wells in 40 countries and territories. By looking at locations, purposes and construction records, they estimated that between 6 and 20% of the wells were no deeper than 5 meters (16 feet) from the groundwater level. If the water table dips by even a few meters, the study authors warn, these wells would run dry.

They also found that wells constructed more recently also bore some meters below the current groundwater level. In areas where groundwater is depleting quickly, such wells will not be an alternative to shallower ones for long.

Despite its importance, we still don’t really know how much groundwater there is and how the reserves fluctuate. All the signs point to a looming crisis.

Groundwater levels can fall because of overextraction, inadequate replenishment, or a combination of factors. A changing climate is a significant threat to groundwater resources because droughts and uneven rainfall can diminish local aquifers.

It’s already happening across the globe, from India to the U.S. A 2020 Nature Communications paper assessed the impact of a changing climate on seven major groundwater reservoirs. It showed that aquifers in the southern plains of the U.S. spanning Texas, Oklahoma, Kansas and New Mexico are likely to see drastic declines in groundwater availability if global temperatures rise unchecked. So will reserves in the Middle East that serve people in Turkey, Syria, Iraq and Iran.

A dried riverbed in western India. | Image by Rhett A. Butler/Mongabay.

In some parts of the world, groundwater availability shapes destinies: whether a family member migrates, children stay in school, or if future generations are mired in debt. It can also fuel conflict and contribute to the rise of climate refugees.

Digging deeper isn’t always an option. Water quality at the deeper ends of aquifers may be poor because minerals tend to get concentrated there. These wells are also costlier to dig. In the Indian state of Punjab, which is predominantly agricultural, larger landowners have the wherewithal to drill deeper wells. They can thus access water where smaller landowners may not be able to, research shows.

“As groundwater levels decline around the world, only the relatively wealthy will be able to afford the cost of drilling deeper wells and paying for the additional power required to pump groundwater from greater depths,” James Famiglietti and Grant Ferguson said in their Science commentary.

Chasing down water is one way to adapt to the situation. Communities can be forced to seek out more remote water sources. In agricultural practice, this may mean small farmers moving away from water-intensive crops or trying to reduce water wastage. But all these adaptations come with a cost and raise concerns that uneven water access will widen existing inequities.

This story was originally published in Mongabay on April 29, 2021. NowThis has published this story with permission.