India could see winter crop cultivation shrink by 20% as groundwater depletes, study finds

Decrease in groundwater levels and the inadequate irrigation capacity of canals could reduce India’s winter crop acreage by up to 20 per cent, a new study has warned.

Indian farmers have been battling depleting groundwater since the 1960s, when an increased reliance on irrigation wells drastically expanded production of water-intensive crops like wheat and rice.

It was earlier believed that a shift to irrigation canals, which divert surface water from lakes and rivers, is one way to overcome this shortfall.

However, the study by researchers based in the US and India, published in the Science Advances journal, concludes that a switch to canal irrigation will not completely compensate for the loss of groundwater in Indian agriculture.

It notes that even if all Indian regions currently using depleted groundwater switch to canal irrigation, winter crop acreage could still decline by 7 per cent nationwide and by 24 per cent in the most severely affected locations.

Furthermore, in the worst case scenario, if farmers keep using groundwater without access to irrigation canals, the winter crop acreage could reduce by 20 per cent across the country.

“Our results highlight the critical importance of groundwater for Indian agriculture and rural livelihoods, and we were able to show that simply providing canal irrigation as a substitute irrigation source will likely not be enough to maintain current production levels in the face of groundwater depletion,” said Meha Jain, a study author and assistant professor at the University of Michigan, in a statement.

Study used satellite images, census data to estimate crop acreage loss

While nearly all Indian farmers plant crops during the monsoon to take advantage of seasonal rains, winter agriculture primarily relies on groundwater irrigation and now accounts for 44 per cent of the country’s annual crop acreage for food grains.

For the study, researchers analysed high-resolution satellite imagery and village-level census data and focused on winter crop acreage.

It is the first such study to use high-resolution empirical data, including census data, about the irrigation methods used in more than 5,00,000 Indian villages to estimate the crop production losses that may occur when overexploited groundwater is used.

According to the team, the distance from existing irrigation canals is strongly linked to decreased acreage planted with winter crops.

They also noted that increased reliance on canals in future could increase inequalities related to irrigation access.

According to the study, lakes and rivers that feed irrigation canals rise and fall in response to rainfall variability, unlike deep groundwater wells. This means as farmers become more reliant on canal irrigation, they would become more vulnerable to rainfall fluctuations, as well as any long-term trends due to climate change.

According to Jain, “These findings suggest that other adaptation strategies, in addition to canal expansion, are needed to cope with ongoing groundwater losses.”

The possibilities suggested by the study include switching from winter rice to less water-intensive cereals, increased adoption of sprinklers and drip irrigation to conserve water in the fields and policies to increase the efficiency of irrigation canals.