Global groundwater levels dwindling: study'

You will have hunger and social unrest,' researcher warns
Last Updated: Friday, September 24, 2010 12:07 PM ET
CBC News

A global survey of groundwater levels appears to show underground supplies are dwindling.

The research, examining groundwater reserves by measuring rainfall and other water sources against evaporation and removal for agriculture and other uses, finds that the rate of depletion more than doubled between 1960 and 2000, to 283 cubic kilometres annually from 126 cubic kilometres per year.

Depletion hotspots include northwest India, northeastern China, northeast Pakistan, California's Central Valley and the midwestern U.S., according to the report.

Groundwater represents roughly 30 per cent of all fresh water in the world. Its depletion is leading to an increase in sea levels, as people remove groundwater, leaving it then to evaporate and fall as rain.

The researchers predict current practices will lead to a crisis, as so much of the world's agriculture relies on groundwater.

"If you let the population grow by extending the irrigated areas using groundwater that is not being recharged, then you will run into a wall at a certain point in time, and you will have hunger and social unrest to go with it," said Marc Bierkens of Utrecht University in the Netherlands, the lead author of the study. "That is something that you can see coming for miles."

The research is to be published in Geophysical Research Letters, a journal of the American Geophysical Union.

Read more: http://www.cbc.ca/technology/story/2010/09/24/groundwater-study-depletion.html#ixzz10YWNTqZa


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Groundwater depletion rate said doubled

WASHINGTON, Sept. 23 (UPI) The rate at which humans are drawing from vast underground stores of groundwater on which billions rely has doubled in recent decades, a Dutch researcher says.

Findings published in the journal Geophysical Research Letters say water is rapidly being pulled from fast-shrinking subterranean reservoirs essential to daily life and agriculture in many regions.

So much water is being drawn from below ground that its evaporation and eventual precipitation accounts for about 25 percent of the annual sea level rise across the planet, the researchers said.

Global groundwater depletion threatens potential disaster for an increasingly globalized agricultural system, Marc Bierkens of Utrecht University in Utrecht, the Netherlands, said.

"If you let the population grow by extending the irrigated areas using groundwater that is not being recharged, then you will run into a wall at a certain point in time, and you will have hunger and social unrest to go with it," Bierkens says. "That is something that you can see coming for miles."

The researchers say the rate at which global groundwater stocks are shrinking has more than doubled between 1960 and 2000, increasing the amount lost from 30 cubic miles to 68 cubic miles per year.

Because the total amount of the world's groundwater is unknown it's hard to estimate how fast the global supply would vanish at this rate, but if water was drained as rapidly from the Great Lakes they would go bone-dry in around 80 years, scientists say.

Link: http://www.upi.com/Science_News/2010/09/23/UPI-NewsTrack-Health-and-Science-News/UPI-47511285282273/



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Groundwater depletion rate more than doubled in recent decades: Study
Washington, Sep 24 (ANI)

After a global assessment of groundwater use, scientists have suggested that groundwater depletion has more than doubled in recent decades.

Today, people are drawing so much water from below that they are adding enough of it to the oceans (mainly by evaporation, then precipitation) to account for about 25 percent of the annual sea level rise across the planet, found researchers.

Soaring global groundwater depletion bodes a potential disaster for an increasingly globalized agricultural system, said Marc Bierkens of Utrecht University.

"If you let the population grow by extending the irrigated areas using groundwater that is not being recharged, then you will run into a wall at a certain point in time, and you will have hunger and social unrest to go with it," warned Bierkens.

Bierkens and colleagues compared estimates of groundwater added by rain and other sources to the amounts being removed for agriculture and other uses, the team taps a database of global groundwater information including maps of groundwater regions and water demand.

The researchers also use models to estimate the rates at which groundwater is both added to aquifers and withdrawn. For instance, to determine groundwater recharging rates, they simulate a groundwater layer beneath two soil layers, exposed at the top to rainfall, evaporation, and other effects, and use 44 years worth of precipitation, temperature, and evaporation data (1958-2001) to drive the model.

Applying these techniques worldwide to regions ranging from arid areas to those with the wetness of grasslands, the team found that the rate at which global groundwater stocks are shrinking has more than doubled between 1960 and 2000.

The new assessment has shown the highest rates of depletion in some of the world's major agricultural centers, including northwest India, northeastern China, northeast Pakistan, California's central valley, and the midwestern United States.

"The rate of depletion increased almost linearly from the 1960s to the early 1990s.

"But then you see a sharp increase which is related to the increase of upcoming economies and population numbers; mainly in India and China," said Bierkens.

As groundwater is increasingly withdrawn, the remaining water "will eventually be at a level so low that a regular farmer with his technology cannot reach it anymore," he added.

The findings were published in the Geophysical Research Letters, a journal of the American Geophysical Union. (ANI)

Link: http://news.oneindia.in/2010/09/24/groundwaterdepletion-rate-more-than-doubled-in-recentdecad.html