Northern India’s Groundwater is Rapidly Disappearing
Northern India’s water tables have fallen by about a fifth more than expected because of excessive use, a major crisis which pose serious threats to the county’s farming, food and potable water supplies, according to a study by NASA hydrologists.
Groundwater resides beneath the soil surface in permeable rock, clay and sand as illustrated in this conceptual image. Many aquifers extend hundreds of feet underground and in some instances have filled with water over the course of thousands of years. Credit: NASA. Source: NASA Earth Science News.
A team of hydrologists, led by NASA’s Matt Rodell said the water is being pumped and consumed faster than the aquifers can be recharged through natural mechanisms. Their research — published in the August 20 issue of Nature — was based on observations from NASA’s Gravity Recovery and Climate Experiment (GRACE), NASA Earth Science Team said.
The map shows groundwater changes in India during 2002-08, with losses in red and gains in blue, based on GRACE satellite observations. The estimated rate of depletion of groundwater in northwestern India is 4.0 centimeters of water per year, equivalent to a water table decline of 33 centimeters per year. Increases in groundwater in southern India are due to recent above-average rainfall, whereas rain in northwestern India was close to normal during the study period. Credit: I. Velicogna/UC Irvine. Source: NASA Earth Science News.
“If measures are not taken to ensure sustainable groundwater usage, consequences for the 114 million residents of the region may include a collapse of agricultural output and severe shortages of potable water,” said Rodell, who led the study.
According to Rodell, groundwater across the three northern Indian states of Rajasthan, Punjab and Haryan has dropped by about 4cm a year between 2002 and 2008.
“The northern Indian states of Rajasthan, Punjab and Haryana have all of the ingredients for groundwater depletion: staggering population growth, rapid economic development and water-hungry farms, which account for about 95 percent of groundwater use in the region.” NASA Earth Science Team said.
“Data provided by India’s Ministry of Water Resources suggested groundwater use was exceeding natural replenishment, but the regional rate of depletion was unknown. Rodell and colleagues had their case study. The team analyzed six years of monthly GRACE gravity data for northern India to produce a time series of water storage changes beneath the region’s land surface.
The map, showing groundwater withdrawals as a percentage of groundwater recharge, is based on state-level estimates of annual withdrawals and recharge reported by India’s Ministry of Water Resources. The three states included in this study are labeled. Credit: NASA/Matt Rodell. Source: NASA Earth Science News.
“They found that groundwater levels have been declining by an average of one meter every three years (one foot per year). More than 109 cubic km (26 cubic miles) of groundwater disappeared between 2002 and 2008 — double the capacity of India’s largest surface water reservoir, the Upper Wainganga, and triple that of Lake Mead, the largest man-made reservoir in the United States.”
“We don’t know the absolute volume of water in the Northern Indian aquifers, but GRACE provides strong evidence that current rates of water extraction are not sustainable,” said Rodell. “The region has become dependent on irrigation to maximize agricultural productivity, so we could be looking at more than a water crisis.”
The Indian government has released an environmental report recently warning that an increasing percentage of its groundwater was unsuitable both for drinking and irrigation, Reuters said.
As animated here, groundwater storage varied in northwestern India between 2002 and 2008, relative to the mean for the period. These deviations from the mean are expressed as the height of an equivalent layer of water, ranging from -12 cm (deep red) to 12 cm (dark blue). Credit: NASA/Trent Schindler and Matt Rodell. Source: NASA Earth Science News.
“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.
“At its core, this dilemma is an age-old cycle of human need and activity — particularly the need for irrigation to produce food,” said Bridget Scanlon, a hydrologist at the Jackson School of Geosciences at the University of Texas in Austin. “That cycle is now overwhelming fresh water reserves all over the world. Even one region’s water problem has implications beyond its borders.”
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