Agroaldea
About a third of the Earth's largest groundwater basins are being rapidly depleted by human consumption..
Two new studies led by the University of California, Irvine (UCI), using data from NASA's GRACE climate satellites, warn that a significant part of humanity is rapidly consuming groundwater without knowing when it could run out.
“Available physical and chemical measurements are simply insufficient”, explains UCI professor and principal investigator Jay Famiglietti. “Considering how quickly we are consuming the world's groundwater reserves, We need a coordinated global effort to determine how much remains.”
Studies are first to comprehensively characterize global groundwater losses with data from space, using readings generated by NASA's twin GRACE satellites.
GRACE measures anomalies in Earth's gravity, that is affected by the mass of water. The researchers found that 13 of the 37 largest aquifers on the planet studied between 2003 and 2013 they were running out, since they receive little or no recharge.
Eight were classified as “stressed”, almost no natural replacement to compensate for use. Five others turned out to be “extremely” o “very stressed”, depending on the replacement level of each one.
The most overloaded aquifers are in the driest areas of the world, where populations largely use groundwater. Climate change and population growth are expected to intensify the problem.
“What happens when a highly stressed aquifer is located in a region with socioeconomic or political tensions that cannot supplement dwindling water supplies quickly enough??” -asks Alexandra Richey., lead author of both studies. “We are trying to raise red flags now to clearly establish where active management today could protect lives and livelihoods in the future.”
The research team found that the Arabian Aquifer System, an important source of water for more than 60 millions of people, It is the one that suffers the most excessive tension in the world.
[quote]The total volume of groundwater is probably much smaller than rudimentary estimates made decades ago.[/quote]
Indus Basin aquifer in northwest India and Pakistan second most stressed, and the Murzuk-Djado Basin in North Africa is the third. California's Central Valley, which is largely used for agriculture and suffers rapid depletion, it's going a little better, but you are still considered highly stressed.
“As we are seeing in California right now, we rely much more on groundwater during drought”, I say Famiglietti. “When examining the sustainability of a region's water resources, It is absolutely necessary to take this dependency into account”.
In a complementary document published in the same journal, Scientists conclude that the world's total remaining volume of usable groundwater is poorly known, with estimates often varying widely.
By comparing satellite groundwater loss rates with the limited data on groundwater availability, The researchers found large discrepancies when projecting the “exhaustion time”.
In the stressed Aquifer System of the northwest of the Sahara, for example, the time of depletion estimates varied between 10 years and 21.000 years.
“We actually don't know how much is stored in each of these aquifers.. Estimates of remaining storage could range from decades to millennia”, Richey said.. “In a water-scarce society, We can no longer tolerate this level of uncertainty., especially since groundwater is disappearing so quickly.”
Study notes groundwater scarcity is already leading to significant ecological damage, including depleted rivers, declining water quality and land collapse.
Underground aquifers are typically found in soil or rock layers deeper beneath the Earth's surface.. The depth and thickness of many large aquifers make it difficult and expensive to drill or not reach the bedrock and understand, where the humidity bottoms are located. But it has to be done, say the authors.