The history of groundwater use dates back to more than 7000 years. Most ancient civilisations, including India’s Harappan civilisation, relied on wells for drinking water. Since the advent of borewells nearly half a century ago, the exploitation of groundwater has grown multifold. Today, groundwater supports the day-to-day needs of billions of people and feeds over 40% of irrigated agriculture. But, how sustainable are our groundwater infrastructure?
A new study shows that up to 20 per cent of all the groundwater wells in the world are at risk of going dry if groundwater levels decline by only a few meters. Researchers from the University of California – Santa Barbara, US, examined records data from approximately 3.9 crore wells in 40 countries around the world. They found that between 6 and 20 per cent of all of the wells around the world currently sit at no more than five metres below their water table, implying that up to 78 lakh wells out of 3.9 crore could run dry very soon.
Researchers suggest that unless this trend changes, access to groundwater may soon become one of the privileges of the rich. “Drilling wells is expensive,” says Scott Jasechko, an assistant professor at UC Santa Barbara. “Even if freshwater exists deep underground, not every individual or household has the capital to drill a new well to access it, which raises concerns about equity when wells run dry.”
The researchers—Debra Perrone and Scott Jasechko—found that the majority of new well constructions also have not taken into consideration the reduced levels of groundwater, and therefore have not been dug deeper than older wells. The study warns that such practice will lead to the new wells running dry just as quickly as the older wells.
Earlier research has proven that the reason for shrinking volumes of water in aquifers is that the extraction rate of groundwater far exceeds the natural replenishing capacity of aquifers. In addition to the massive amounts of groundwater withdrawn, increased frequency and length of droughts due to global warming will exacerbate the threat to water security to the vulnerable sections of the society.
“In some places, groundwater levels are close to the bottom of wells,” Perrone stated. “If groundwater levels continue to decline in these places, wells will go dry, leaving people without access to water.”
To arrive at these results, Perrone and Jasechko spent the better part of six years as they compiled the data from more than 100 unique databases around the world. They manually went through the entire dataset to process the data from 39 million records of functional wells that included depth, purpose, location and construction date.
“We wanted to be sure we understood the limitations and nuances for each database we analyzed,” Jasechko said, justifying their decision to avoid using data algorithms or artificial intelligence for their study.
The study was published in the journal Science on Friday, April 23, and can be accessed here.
(with inputs from IANS)
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