Excessive strain on India’s groundwater threatens its agricultural sector and current government interventions have been inadequate to the scale of the problem, according to a new report published in the journal Science Advances.
The authors used satellite imagery, government and local data, and past research to conduct a country-wide analysis of irrigation methods and the impact of dwindling water resources on agriculture. They found that government efforts to extend canal-based irrigation to villages cannot make up for disappearing groundwater.
"Understanding the complex relationship between food security and water availability is crucial as we prepare for future rainfall variability due to global climate change," said co-author Gillian Galford, of the University of Vermont, in a statement.
India is home to 600 million farmers who collectively produce around 10% of the world’s crops. They primarily irrigate their crops with shallow wells or deeper tube wells that draw water from within the ground.
Over the past several decades, aquifers have been severely depleted largely because of farming. In fact, a third of the country’s aquifers are being pumped “much faster” than they can replenish. Of the 245 billion cubic meters of groundwater consumed in India annually, 90% goes to agriculture.
The north of the country is particularly threatened by water shortages, according to CNN. In 2019, the four main reservoirs in the city of Chennai nearly ran dry because of lack of rainfall.
Sources of groundwater are also severely polluted. In fact, a report by the National Institution for Transforming India found that 70% of freshwater is contaminated. This pollution causes an estimated 200,000 deaths annually.
Precipitation patterns are changing, increasing the likelihood of both floods and droughts, and the Himalayan glaciers, which supply water to key rivers throughout the country, are disappearing.
For farmers, this means that an indispensable resource is becoming more scarce.
The authors of the report note that the Indian government has tried to compensate for dwindling groundwater availability by building more canals that ship water to strained communities. But canal-based irrigation has been less productive than traditional forms, according to the report.
In fact, canal-irrigated villages are 52% less likely to plant crops in the winter season than villages that rely on tube wells. The crop areas of canal-irrigated villages are also 22% smaller on average than areas irrigated with tube wells.
Water transported via canals depletes the lakes and rivers that are subject to the variability of changing weather patterns. Further, canal-based irrigation leads to regional disparities in water access. Villages that are closer to lakes and rivers will be more likely to receive water from canals first.
What this all means is that even if all villages transitioned to canal-based irrigation in response to disappearing ground water, the amount of crops harvested in the winter season could decline by between 7% and 24% across the country, with some regions experiencing declines as steep as 68%. The report notes that while the monsoon season generates enough rainfall to support farming in the summer, the country harvests 44% of its crops during the winter season when rainfall is less abundant. The country can hardly afford declining agricultural output at a time when demand for food is growing.
"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 study lead author Meha Jain, of the University of Michigan, in a statement.
The authors say that new forms of adaptation should be implemented, such as switching to less water-intensive crops and adopting other forms of irrigation such as drip and sprinkler methods that use less water.
Nearly all countries are grappling with growing water shortages. By 2050, the United Nations estimates that more than 5 billion people could be affected by water scarcity. Since agriculture accounts for the majority of water use worldwide, the global food system faces a reckoning in the years ahead unless it learns to conserve water.