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Researchers at the University of Michigan found that as temperatures rose in India, farmers increased their use of groundwater for irrigation. Groundwater loss rates could triple by 2080 if current trends continue, posing a serious threat to India's ability to meet its water and food needs.
According to the study, reduced water availability in India due to groundwater depletion and climate change could threaten the livelihoods of more than one-third of the country’s 1.4 billion residents and have global implications.
Meha Jain, senior author of the study and an assistant professor at the university’s School for Environment and Sustainability said, “We find that farmers are already increasing irrigation use in response to warming temperatures, an adaptation strategy that has not been accounted for in previous projections of groundwater depletion in India. This is of concern, given that India is the world’s largest consumer of groundwater and is a critical resource for the regional and global food supply.”
The lead author of the study is Nishan Bhattarai of the Department of Geography and Environmental Sustainability at the University of Oklahoma, formerly a postdoctoral researcher in Jain’s U-M lab. The researchers also used temperature and precipitation projections from 10 climate models to estimate future rates of groundwater loss across India, said a release by the university.
The new study takes into account the fact that warmer temperatures may increase water demand from stressed crops, which in turn may lead to increased irrigation by farmers, the release said.
“Using our model estimates, we project that under a business-as-usual scenario, warming temperatures may triple groundwater depletion rates in the future and expand groundwater depletion hotspots to include south and central India,” Bhattarai said.
The team compiled a dataset for the study using high-resolution satellite observations to measure crop water stress in addition to historical records of temperature and precipitation. The researchers discovered that increased monsoon precipitation was unable to slow the groundwater declines caused by rising temperatures and decreasing winter precipitation.
In addition to Jain and Bhattarai, the authors of the Science Advances study are David Lobell of Stanford University, Balwinder Singh of the International Maize and Wheat Improvement Center in India and the Department of Primary Industries and Regional Development in Western Australia, Ram Fishman of Tel Aviv University, William Kustas of the U.S. Department of Agriculture and Yadu Pokhrel of Michigan State University.
The research was funded by a NASA Land-Cover Land-Use Change Grant and a NASA New Investigator Program award to Jain. It was supported in part by the US Department of Agriculture’s Agricultural Research Service.