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 Nature1.
Across the world, human civilizations depend largely on tapping vast reservoirs of water that have been stored for up to thousands of years in sand, clay and rock deep underground. These massive aquifers — which in some cases stretch across multiple states and country borders — provide water for drinking and crop irrigation, as well as to support ecosystems such as forests and fisheries.
Yet in most of the world’s major agricultural regions, including the Central Valley in California, the Nile delta region of Egypt, and the Upper Ganges in India and Pakistan, demand exceeds these reservoirs' capacity for renewal.
“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 and his colleagues combined a global hydrological model and a data set of groundwater use to estimate how much groundwater is being extracted by countries around the world. They also estimated each aquifer's rate of ‘recharge’ — the speed at which groundwater is being replenished. Using this approach, the researchers were able to determine the groundwater ‘footprint’ for nearly 800 aquifers worldwide (see map above).
In calculating how much stress each source of groundwater is under, Gleeson and colleagues also looked in detail at the water flows needed to sustain the health of ecosystems such as grasses, trees and streams.
Read more: http://www.nature.com/news/demand-for-water-outstrips-supply-1.11143
Across the world, human civilizations depend largely on tapping vast reservoirs of water that have been stored for up to thousands of years in sand, clay and rock deep underground. These massive aquifers — which in some cases stretch across multiple states and country borders — provide water for drinking and crop irrigation, as well as to support ecosystems such as forests and fisheries.
Yet in most of the world’s major agricultural regions, including the Central Valley in California, the Nile delta region of Egypt, and the Upper Ganges in India and Pakistan, demand exceeds these reservoirs' capacity for renewal.
“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 and his colleagues combined a global hydrological model and a data set of groundwater use to estimate how much groundwater is being extracted by countries around the world. They also estimated each aquifer's rate of ‘recharge’ — the speed at which groundwater is being replenished. Using this approach, the researchers were able to determine the groundwater ‘footprint’ for nearly 800 aquifers worldwide (see map above).
In calculating how much stress each source of groundwater is under, Gleeson and colleagues also looked in detail at the water flows needed to sustain the health of ecosystems such as grasses, trees and streams.
Read more: http://www.nature.com/news/demand-for-water-outstrips-supply-1.11143
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