Scientists from the University of California have been using small variations in the Earth’s gravity to identify trouble spots around the globe where people are making unsustainable demands on groundwater, one of the planet’s main sources of fresh water.
They found problems in places as disparate as North Africa, northern India, northeastern China and the Sacramento-San Joaquin Valley in California.
University of California’s Center for Hydrologic Modeling has developed Grace, the Gravity Recovery and Climate Experiment, that uses twin satellites to produce precise data on gravitational variations. The results are “redefining the field of hydrology”. Grace detects changes in ice, snow and water storage, surface water, soil moisture and groundwater.
Making such data available may increase sensitivities
in arid regions where groundwater basins are often shared by unfriendly neighbors — India and Pakistan, Tunisia and Libya or Israel, Jordan, Lebanon, Syria and the Palestinian territories — that are prone to suspecting one another of excessive use of this shared resource.
Grace can only supply reliable data for very large aquifers.
In northern India, the use of data from Grace in a study on aquifer depletion has led to some resistance.
“When in a place like India you say, ‘We’re doing something that is unsustainable and needs to change,’ well, people resist change. Change is expensive.”
Source: Felicity Barringer, New York Times, 30 May 2011