India's groundwater crisis threatens food security for hundreds of millions, study says

Indian women carrying drinking water from a municipal water tanker in Shankargarh, Uttar Pradesh, on June 6, 2019.

(CNN)Hundreds of millions of people in India face a serious threat to their livelihoods and food security due to overexploitation of vital water supplies, according to the authors of a new study.

India is one of the world's biggest crop producers and more than half of its 1.3 billion people rely on agriculture for their livelihoods. But the groundwater that makes up 40% of the country's water supply has been steadily depleting for years.
The study, published Wednesday in the journal Science Advances, found that overuse of groundwater could cause winter harvests in some regions of the country to fall up to two thirds by 2025.
    A team of international researchers analyzed satellite imagery and census data to gauge the impact on winter harvests, which account for 44% of the country's annual cropped acreage for food grains, according to the study. Winter agriculture relies heavily on groundwater irrigation -- as opposed to other seasons that can take advantage of heavy monsoon rains.
      Indian food production has skyrocketed since the 1960s, as farmers began widely using tube wells, which draw water from deep underground. This has allowed them to continue farming even during dry seasons when there isn't rain or sufficient surface water -- but over-extraction has left "critically low groundwater availability" in the country's northwest and south, according to the research.
      "Many studies have shown that India has large groundwater depletion, but to date it has been unclear what the impacts of this depletion could have on agricultural production," said lead author Meha Jain, an assistant professor at the University of Michigan's School for Environment and Sustainability.
      The researchers found that if farmers in over-exploited regions lose all access to groundwater, and if that irrigation water isn't replaced by water from other sources, winter harvests could decrease by 20% nationwide and by 68% in the most severely affected areas.
        This is a worst-case scenario, and the damage could be mitigated if authorities take action and adopt alternative irrigation options, the study said. The government has already been widely pushing the adoption of canal irrigation, which diverts surface water from lakes and rivers, and could help offset some of the losses.