“There’s no water, so there’s no harvest, so there’s no income,” said Adinath Suryawanshi, a farmer whose family has gone into debt drilling wells that turned out to be dry. “I think there’s really no way out. All I can do is cope. And I think that’s the fate of every farmer.”
Falling water tables and crushing burdens of debt have contributed to a growing sense of desperation in the western state of Maharashtra, where farmers have been committing suicide in large numbers. Some families have turned to chopping down trees on their land to sell off the wood. Many young people have given up farming and moved away to cities to look for work.
In large portions of India, from the plains that spread out below the Himalayas to the country’s southern plateau, water is being quickly drained from the ground and aquifers are rapidly declining. In some areas, government data show groundwater levels have dropped by an average of more than 30 feet since 2005.
It’s a growing crisis that threatens the future of irrigated agriculture in some of India’s prime farming areas, and it’s also putting at risk the main drinking water sources used by hundreds of millions of people.
India relies heavily on groundwater, with an estimated 25 million to 35 million wells in operation, many of them on small farms. Wells have enabled increasing water use in places where rivers and canals are too far away or are already tapped out or polluted.
As wells have proliferated over the past half century, the country has become the world’s largest and fastest growing user of groundwater. Scientists estimate that about 250 cubic kilometers of water is sucked from India’s aquifers each year – more than half the volume of Lake Erie, and more than the combined annual groundwater usage of the United States and China.
Researchers at the University of California, Irvine, and NASA have found that more than half of the world’s largest 37 aquifers are declining.
The U.N. also estimates that the world will face a 40 percent shortfall in the global water supply by 2030 unless dramatic steps are taken to improve the management of water. Within a decade, 1.8 billion people are projected to be coping with severe water scarcity and two-thirds of the global population could be living with stressed water supplies.
Adinath Suryawanshi stands by his open well, which once provided water for his family on their 7.5-acre farm in Maharashtra state, India. The well, which was blasted open with dynamite years ago, has gone dry. The family has tried drilling deeper borehole wells, but they haven't found water to pump. They are now in debt and struggling to make a living while relying on the rains to water their crops.
(Photo: Steve Elfers, USA TODAY)
Quantifying renewable groundwater stress with GRACE
Groundwater is an increasingly important water supply source globally. Understanding the amount of groundwater used versus the volume available is crucial to evaluate future water availability. We present a groundwater stress assessment to quantify the relationship between groundwater use and availability in the world's 37 largest aquifer systems. We quantify stress according to a ratio of groundwater use to availability, which we call the Renewable Groundwater Stress ratio. The impact of quantifying groundwater use based on nationally reported groundwater withdrawal statistics is compared to a novel approach to quantify use based on remote sensing observations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. Four characteristic stress regimes are defined: Overstressed, Variable Stress, Human-dominated Stress, and Unstressed. The regimes are a function of the sign of use (positive or negative) and the sign of groundwater availability, defined as mean annual recharge. The ability to mitigate and adapt to stressed conditions, where use exceeds sustainable water availability, is a function of economic capacity and land use patterns. Therefore, we qualitatively explore the relationship between stress and anthropogenic biomes. We find that estimates of groundwater stress based on withdrawal statistics are unable to capture the range of characteristic stress regimes, especially in regions dominated by sparsely populated biome types with limited cropland. GRACE-based estimates of use and stress can holistically quantify the impact of groundwater use on stress, resulting in both greater magnitudes of stress and more variability of stress between regions.