WATER CRISIS?: Satellite measurements show that northwestern India is losing a foot of groundwater from its aquifer yearly.
Image: NASA/Trent Schindler and Matt Rodell
-
The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
Read More »
The fields of barley, rice and wheat that feed much of India are running out of water, according to a new study based on satellite data and published online in Nature today. The heartland of last century's Green Revolution lost 109 cubic kilometers of water from its Indus River plain aquifer between August 2002 and October 2008. (Scientific American is part of the Nature Publishing Group.)
"By our estimates, the water table is declining at a rate of one foot per year averaged over the Indian states of Rajasthan, Punjab and Haryana, including the national capital territory of Delhi," an area in northwestern India that covers more than 438,000 square kilometers, says NASA hydrologist Matthew Rodell, lead author of the paper. "We are not able to estimate the total amount of groundwater in storage [in the aquifer], so we can't say when it will be gone, but residents are already feeling the effects and it will only become worse."
The consequences include wells that run dry, water shortages in India's capital and, potentially, a decline in yields from agriculture. India's Ministry of Water Resources has long suggested that tapping the aquifer for irrigation was exceeding the limited regional rainfall that replenishes its water, and the World Bank has warned that the country faces a water crisis. On a yearly basis, nearly 63 cubic kilometers of water are drawn from the aquifer, whereas the Indian government estimates that roughly 45 cubic kilometers of water recharge the aquifer annually.
The scientists relied on data from the pair of GRACE satellites—NASA's Gravity Recovery and Climate Experiment orbiters launched in 2002—that measure subtle changes in Earth's gravitational field, which are often the result of shifting water, whether on the surface or deep beneath it. In addition to large-scale water losses detected in Greenland and other polar regions by the GRACE satellites, northwestern India stands out as another area of rapid water loss. "Basically, it is like we weigh Earth every month and we look at the changes," explains geophysicist Isabella Velicogna of the University of California, Irvine, part of the research team.
The primary reason for such groundwater depletion is irrigation, which has fed the Green Revolution that transformed cereal production in the region and helped sustain a growing population that has reached 114 million people. Between 1970 and 1999 irrigated fields in India tripled in overall extent to cover more than 33 million hectares.
That irrigation now looks unsustainable: "The problem is that groundwater consumption was not capped at a sustainable level and now it will be difficult to curb demand," Rodell notes.
It is also clear that global warming's accelerated melting of the nearby Himalayan glaciers is not the primary culprit in the region's water deficit. These meltwaters feed the rivers of northwestern India and beyond, but that water soon flows out of the area and is lost to it. Even with a generous assumption that all Himalayan glacial melting since 1962 (roughly 13.4 cubic kilometers per year) was concentrated in the 150-kilometer stretch of land closest to the study zone rather than spread across the entirety of the Himalayas, the scientists could explain, at most, 15 percent of the water loss in northwestern India. And the arid region's rainfall levels were above the average of 50 centimeters per year from 2002 to 2008.
The water contained in the Indus River plain aquifer, once pumped, is lost to the region via evaporation from irrigation or transpiration from irrigated plants. And GRACE has detected similar depletion in the U.S., as well, including the Ogallala Aquifer under the western plains and the groundwater in the California's Central Valley. "Groundwater resources are being rapidly depleted in many regions of the world," says U.C. Irvine hydrologist James Famiglietti, another team member. "These signals of groundwater loss, in particular in the Central Valley, are very strong."
The solution may be to impose limits on pumping aquifer water— particularly in the case of northwestern India, which uses it to fill seasonal rice paddies covering some 38,000 square kilometers. "If farmers would shift away from water-intensive crops, such as rice, and implement more efficient irrigation methods, that would help," Rodell says.
As population growth continues and food production increases, however, demand for groundwater will only increase, Famiglietti warns. Nevertheless, this research, he says, "suggests that we can keep track of rates at which groundwater reserves are dwindling the world over."
See what we're tweeting about
15 Comments
Add CommentAs fast as you can move water around, people are reproducing and consuming more. Only birth control can save billions from dying of drought and war brought about by competition for water and other resources.
Reply | Report Abuse | Link to thisNow matter how much water you move around people will reproduce and consume more. Birth control is the only way to stop billions of people dying horribly from drought and water wars. Unfortunately our economic systems are based on continuous growth so this idea will be discouraged until it is too late.
Reply | Report Abuse | Link to thisDamn, now my comments are reproducing too
Reply | Report Abuse | Link to thisWorld's number one problem isn't water nor oil nor any commodity of modern life------it's the stupidity level of those religious reproduction machines overpopulating the planet.
Reply | Report Abuse | Link to thisPeople of India are not havesting water. Once It is done the problem will reduce
Reply | Report Abuse | Link to thiswater harvesting should be done to avoid big problem
Reply | Report Abuse | Link to thisBut how is that no body is even mentioning anything about reducing water consumption? Why is the focus is always and exclusively on the supply side. I will say this to Delhi folks - wash your car no more than 2 times a week and that too with water treated to potable levels (!) (not every morning) and there are nearly 2 million cars in this metropolis of about 15 million. Let us see what happens.
Reply | Report Abuse | Link to thisRaghuram Ekambaram
But how is that no body is even mentioning anything about reducing water consumption? Why is the focus is always and exclusively on the supply side. I will say this to Delhi folks - wash your car no more than 2 times a week and that too with water treated to potable levels (!) (not every morning) and there are nearly 2 million cars in this metropolis of about 15 million. Let us see what happens. And, this is just a sampler.
Reply | Report Abuse | Link to thisRaghuram Ekambaram
shortage of water is a serious issue to overcome this we have to use more and more recharge well in canals and other water carrying system also save the runoff area which is covered by concrete day by day. concrete can be replaced by porous concrete so that water can infilter through it.
Reply | Report Abuse | Link to thisHere in California. The Pajaro River aquafer (Watsonville - source of strawberries for the nation) is heavily depleted and salt water from the Pacific is steadily creeping in. The Santa Clara Valley (AKA Silicon Valley) is somewhere near 10 feet lower than pre-irrigation/development times. Why is this not mentioned? Why is the impending "disaster" in India made so much of? I sense some Euro-American hubris here. After all, if our present track of human development is the global standard for defining "success", then India gets to develop, too. Solution: our model of limitless human population growth needs updating. Now.
Reply | Report Abuse | Link to thisHere in California: I sense that as this is happening in India, it is posed as a hideous catastrophe, but this has gone on in developed nations for decades. No one gave a damn while California's Pajaro Valley aquafer (Watsonville - home to a thriving strawberry growing industry) was stripped and salt water from the Pacific moved in during the climb to corporate agribusiness success or the fact that Santa Clara Valley (AKA Silicon Valley) ground levels have dropped 10-20 feet since the early 1900s. Now that the US (and other developed nations) have theirs, shock at India's overdraft is misplaced, and is not an appropriate nationality issue. It is a GLOBAL, human overpopulation issue. Look at home for solutions, do not target India for doing what our current model of natioanl success decrees as the usual metric - unending expansion and population growth at the expense of natural sustainability limitations.
Reply | Report Abuse | Link to thisIt is hard to have a lot of sympathy for overpopulated areas. You bred beyond what the natural resources can support, and now you don't have enough resources, and are crying about how everyone around you should make more. Tough. You overpopulated, now it's your job for your weak, sickly, and undesirable to start dying off. Humans are still ruled by the unsympathetic mechanics of the universe, and not the other way around.
Reply | Report Abuse | Link to this100% agree on birth control is the best solutions but I think it won't work or pretty impossible to work. As the invisible hand of Adam Smith told us individuals that minding their own business will do great to the society/economy as a whole and as professor Garrett Hardin said when they make too many babies the invisible foot will kick in and the society and environment suffer. Tragedy of the Commons.
Reply | Report Abuse | Link to thisThe only outcome I see now is more and more natural disasters will create havoc in every nations but those with economy power will suffer less and the poor pay the ultimate price.
Um... the planet has a FINITE carrying capacity of needy (emotionally and in terms of resources) human animals... spawning out of control.
Reply | Report Abuse | Link to thisAt this moment, there is scarcity in water/drought... perilously thin topsoil... desertification at an alarming pace, with widespread erosion due to deforestation... not to mention AGW exacerbated by urban heat sinks, seriously declining ocean coral and fish stocks... pollution... etc.
HUMANITY has a choice... it can either proceed along a path of responsible environmental stewardship and curb it's reckless reproductive impulse (often driven by dimwitted religious dogma) OR... suffer massive malnutrition, hunger and famine... death and epidemics... and wars to control what resources remain.
The time to "get sustainable"... is... now.
I was always shocked at the wasteful flood irrigation that is customary in many places in India. Ask the Israelis how to farm with limited water. I am sure they could show you a thing or two. Too much water is just wasted.
Reply | Report Abuse | Link to this