Recent gravitational data from NASA’s twin Gravity Recovery and Climate Experiment (GRACE) satellites shows that the world’s largest underground aquifers are running out of water at alarming rates.
According to analysed data between 2002 and 2013, more than half of the world’s largest aquifers are being depleted.
“Twenty-one of the world’s 37 biggest aquifers have passed sustainability tipping points ... they are being depleted,” said Jay Famiglietti, the study leader and senior water scientist at NASA Lab in California.
Out of this 21, eight were found “over-stressed” since there is “nearly no replenishment” for the water that humans use. Another five basins which have “some water flowing back to them” are identified as “extremely or highly stressed.”
The study, published in the Water Resources Research journal, shows that the most stressed basin in the world is the Arabian Aquifer which supplies water for at least 60 million people.
It’s followed by the Indus Basin aquifer of India and Pakistan and the Murzuq-Djado Basin in North Africa.
Underground aquifers supply 35 percent of the water that humans use. In dry years, this number can reach 46 percent, the study finds.
Although scientists can determine how much water is used by observing subtle changes in Earth’s gravitational pull, they don’t know how much water is left.
"Given how quickly we are consuming the world's groundwater reserves, we need a coordinated global effort to determine how much is left," Famiglietti said.