Drought Causes Western US to Rise
Severe drought affecting the western United States in recent years is not only influencing water restrictions for residence and creating problems for crops and wildlife, but it's changing the landscape by causing land to rise up in elevation.
Scientists at Scripps Institution of Oceanography at UC San Diego discovered that the growing, broad-scale loss of water is causing the entire western U.S. to rise up while investigating ground-positioning data from GPS stations.
Scripps researchers Adrian Borsa, Duncan Agnew, and Dan Cayan found that the water shortage is causing an "uplift" effect up to 15 millimeters (more than half an inch) in California's mountains and on average four millimeters (0.15 of an inch) across the west. From the GPS data, they estimate the water deficit at nearly 240 gigatons (63 trillion gallons of water), equivalent to a four-inch layer of water spread out over the entire western U.S.
While poring through various sets of data of ground positions, Borsa, a Scripps assistant research geophysicist, kept noticing the same pattern over the 2003-2014 period: All of the stations moved upwards in the most recent years, coinciding with the timing of the current drought.
Agnew, a Scripps Oceanography geophysics professor says the GPS data can only be explained by rapid uplift of the tectonic plate upon which the western U.S. rests.
For Cayan, a research meteorologist with Scripps and USGS, the results paint a new picture of the dire hydrological state of the west.
"These results quantify the amount of water mass lost in the past few years," said Cayan. "It also represents a powerful new way to track water resources over a very large landscape. We can home in on the Sierra Nevada mountains and critical California snowpack. These results demonstrate that this technique can be used to study changes in fresh water stocks in other regions around the world, if they have a network of GPS sensors."
Results of the study, which was supported by the U.S. Geological Survey (USGS), appear in the August 21 online edition of the journal Science.
Read more at the Scripps Institute of Oceanography.
Drought image via Shutterstock.