Warming Could Push India Toward a Groundwater Crisis
in the journal Science Advances. India already pumps up more underground water than any other country, largely to irrigate staple crops like wheat, rice and maize. But hotter temperatures are drying out fields and leaving less moisture to soak into the soil and replenish the aquifers below. Unless big steps are taken to promote water efficiency, underground supplies could shrink between 2041 and 2080 at three times the present rate, the new estimates suggest. Groundwater is vital for farming in India, supplying 60 percent of all irrigation. But growers in parts of the country are already starting to exhaust aquifers layers of water-soaked dirt and rock that could take centuries to refill. And, at the moment, India doesnt have the dams and other infrastructure needed to significantly increase its river-fed irrigation. If you run out of groundwater, there arent other quick fixes, like providing canal irrigation, that can get you to the same level of production, said Meha Jain, an assistant professor at the University of Michigans School for Environment and Sustainability, who contributed to the new research. The researchers first looked at the relationship between groundwater levels, climate and crop water stress in India between 2004 and 2013. They then estimated how groundwater use might respond to three major effects of global warming: greater evaporation, during the summer monsoon season and decreased rain in winter. The researchers found that the additional summertime rain could help refill aquifers, though not by enough to offset increased evaporation from warmer temperatures and increased irrigation needs during the drier winters. When the temperature is warming, this recharge is actually decreasing in monsoon season, said Nishan Bhattarai, an assistant professor of geography and environmental sustainability at the University of Oklahoma, who led the new research. So far, Indias groundwater overuse has been most severe in the northwestern breadbasket states of Punjab and Haryana. But the researchers modeling suggests that problems could arise by 2050 in the countrys southwest, where aquifers of hard rock cant hold as much water as those in other areas. In their projections, the authors didnt try to predict the effects of water-saving changes that havent yet occurred on a large scale in India. These include shifts to less thirsty crops like millet, use of more efficient watering techniques like drip irrigation and results from changes in government policy, such as free or cheap electricity in rural areas, which have increased groundwater extraction by enabling poor farmers to run electric pumps. They also didnt try to account for the possible physical limits to water pumping in other words, the very real likelihood that wells in parts of India will go completely dry. Many growers in India work on small plots, not industrial farms, so it can be hard to determine how many of them are adopting more environmentally sustainable methods. Dr. Jain is involved in that use satellite-mounted sensors to map agricultural practices at the level of individual fields. Were in the golden age of satellite data, she said. Thats allowing us to answer these questions at scales that just historically have not been possible. is a climate reporter. He joined The Times in 2017 and was part of the team that won the 2021 Pulitzer Prize in public service for coverage of the coronavirus pandemic.