Reuters — A drought has robbed the U.S. West of 63 trillion gallons (238 trillion litres) of water, and with all that weight off the land the ground in the region has risen by several millimetres, according to a study released on Thursday.
The findings by scientists at Scripps Institution of Oceanography at the University of California, San Diego, were published in the online edition of the journal Science.
The researchers relied on data from global positioning system (GPS) stations throughout the West, measuring how much GPS sensors showed the land had risen beneath them.
The uplift is the largest in the U.S. West since researchers began using GPS data 10 years ago. The researchers did not find the uplift has any effect on the likelihood of earthquakes.
The research underscores the severity of the drought in the West, which in California is expected to cost the state economy $2.2 billion in lost crops, jobs and other damages.
The 63 trillion gallons of water missing in the U.S. West is the equivalent of a four-inch (10-cm) layer of water spread across the entire region, researchers found.
On average, the loss of water resulted in an average uplift of the land in the West of four millimetres (0.15 inch), with up to 15 millimetres (0.6 inch) of uplift seen in California’s mountains, according to Scripps.
“The amount of uplift that occurs from 2013 onward both in the magnitude and extent was unlike anything in the GPS record that we had,” said Scripps researcher Adrian Borsa. “We were tremendously surprised that nobody had found it before, we considered ourselves very lucky.”
The water that has left the West has not simply disappeared, it has just been redistributed to other parts of the globe, he said.
The GPS systems used for the study were originally deployed for the study of plate tectonics.
But this novel use of the data, especially due to its value in estimating changes in underground aquifers and in snowcaps, could help officials in charge of water management plan for how to distribute the valuable natural resource, researchers said.