India extracting groundwater at three times the replenishment rate
By Mason Inman for National Geographic News
Published December 31, 2010 This story is part of a special National Geographic News series on global water issues. Nearly a third of India is suffering from chronic water shortages, and making up for it with “the world’s largest groundwater mining operation,” according to experts. A band of land stretching across northern India, at the foot of the Himalayan Mountains, is one of the most heavily populated and intensely irrigated regions in the world. The area is chronically short of water. But the region still has a limited supply of it in underground aquifers, according to water resources expert Shama Perveen of Columbia University. According to a new study by Perveen and her colleagues, Upmanu Lall and Naresh Devineni, some parts of India are using groundwater three times faster than it’s being replenished. The team’s new analysis draws on a 100-year record of daily rainfall in India, reflecting how much water has been available in various parts of the country as its residents endured both droughts and floods. By estimating water needs over dry spells and across decades, and comparing the estimate with actual rainfall, they found that many areas have been falling chronically short for many years. The findings, presented this month at an American Geophysical Union meeting in San Francisco, fit with the results from gravity-sensing satellites that have detected the loss of groundwater across the heavily irrigated areas of northern India—with the extraction of water at about 11 billion cubic yards (9 billion cubic meters) of water per year over the past decade. (Read: “NASA Satellites Track Vanishing Groundwater.”) …
