Groundwater levels have fallen 20 per cent more than expected in northern India, Nasa satellite images have revealed.
A team of experts has found the underwater supply in the region is being pumped and consumed by the burgeoning population, and could spark a major food and water crisis.
The study, led by Matthew Rodell from Nasa said groundwater across three states, including the New Delhi region, dropped at a rate of 1.6 inches per year between 2002 and 2008.
That depletion is double the capacity of India's largest reservoir and is around 20 per cent higher than previous estimates by Indian authorities. More than 110 million people live across the three states, or nearly twice the population of Britain.
The findings, published in the journal Nature, are based on data from Nasa's Gravity Recorvery and Climate Experiment (GRACE).
A pair of satellites orbiting 300miles above Earth the surface sense changes in Earth's gravity field. Changes in underground water masses affect gravity enough to provide a signal that can be measured by the GRACE spacecraft.
Groundwater levels respond slowly to changes in weather and can take months or years to replenish once pumped for irrigation.
The map shows groundwater changes in India during 2002-08, with losses in red and gains in blue, based on GRACE satellite observations.
'GRACE provides strong evidence that current rates of water extraction are not sustainable,' said Rodell.
'If measures are not taken to ensure sustainable groundwater usage, the consequences for the 114million residents of the region may include a collapse of agricultural output and severe shortages of potable water.'
The trend is particularly alarming because it came in years where there was no shortage of rainfall.
The Indian government released an environmental report this week that said a growing percentage of its groundwater was neither drinkable nor could be used for irrigation.
'This illustrates that degraded water quality can contribute to water scarcity as it limits its availability for both human use and the ecosystem,' the Indian report said.
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