Worldwide Demand for Water Outstrips Supply: Study
Groundwater use is unsustainable in many of the world's major agricultural zones
Degree to which aquifers important for farming are under stress. (Gleeson, T. et al.)Almost
one-quarter of the world’s population lives in regions where
groundwater is being used up faster than it can be replenished,
concludes a comprehensive global analysis of groundwater depletion, published this week in Nature.
The
world's oldest and largest acquifers, according to the study, have
supplied civilization with water for agricultural and industrial use for
thousands of years, but are now under threat from over-extraction and
the underground reservoirs can no longer replenish themselves at a
sustainable rate.
“This overuse can lead to decreased groundwater availability for both
drinking water and growing food,” says Tom Gleeson, a hydrogeologist at
McGill University in Montreal, Quebec, and lead author of the study.
Eventually, he adds, it “can lead to dried up streams and ecological
impacts”.
Gleeson said irrigation for agriculture drives much of the demand and
is the main driver for the fragility of the acquifers. According to the
study, India, Pakistan, Saudi Arabia, Iran, Mexico, and the United
States lead the global pack of water-thirsty nations.
The researchers, from McGill University in
Montreal and Utrecht University in the Netherlands, combined groundwater
usage data from around the globe with computer models of underground
water resources to come up with a measure of water usage relative to
supply.
In addition, the scientists calculated how much stress each source of
groundwater is under and looked in detail at the water flows needed to
sustain the health of ecosystems such as grasses, trees and streams.
“To my knowledge, this is the first water-stress index that actually
accounts for preserving the health of the environment,” says Jay
Famiglietti, a hydrologist at the University of California, Irvine, who
was not involved in the study. “That’s a critical step.”
According to Reuters, "Gleeson said limits on
water extraction, more efficient irrigation and the promotion of
different diets, with less or no meat, could make these water resources
more sustainable."
SOURCE: http://www.commondreams.org/headline/2012/08/09 
No comments:
Post a Comment