The current, severe drought has not only gripped New Mexico and the western United States for several years, it has also lifted up the land itself, positioning buildings, streets and mountains in Albuquerque about 0.15 of an inch higher than a decade ago.
That news comes from the Scripps Institution of Oceanography at the University of California, San Diego, in a study published Thursday in the online edition of the journal Science.
“It probably doesn’t change life for people in Albuquerque or the Southwest, but it’s significant that so much water is being moved around that it can cause the land to move up or down,” said a local scientist, University of New Mexico geophysicist Brandon Schmandt. “This is an amazing measurement, one that we haven’t had access to before.”
The effect of the drought, which Scripps describes as a “growing, broad-scale loss of water … causing the entire western U.S. to rise up like an uncoiled spring,” is even more pronounced in the mountains of California, where the “uplift effect” is more than half an inch.
Researchers Adrian Borsa, Duncan Agnew and Dan Cayan studied ground positioning data from hundreds of GPS stations around the West. The effect stems from a cumulative water loss estimated at an astounding 62 trillion gallons, the equivalent of a six-inch layer of water spread over the entire western United States, the scientists wrote.
Reviewing data of ground positions from hundreds of highly precise GPS stations in the National Science Foundation’s Plate Boundary Observatory and other networks throughout the West, Borsa, a Scripps assistant research geophysicist, noticed a recurring pattern: From 2003 to 2014, all of the stations moved upward. The movement coincided with the timing of the drought.
Agnew, a geophysicist who specializes in studying earthquakes and how they help shape the earth’s crust, said the GPS data “can only be explained by rapid uplift of the tectonic plate upon which the western U.S. rests.” Californians, he added, should not worry, as the uplift will have little, if any, effect on the San Andreas fault and does not increase the risk of earthquakes.
Schmandt, who was not involved in the study, said he was not surprised by the findings, although the scope of the uplift is something new. Locally, GPS systems built for other purposes have also measured land uplift, he said.
The absence of water attributed to the drought represents the displacement of “a lot of weight, a lot of mass,” Schmandt said.
But a silver lining can be found in the developing science of tracking and measuring water resources.
“These results quantify the amount of water mass lost in the past few years,” said Cayan, a research meteorologist with Scripps and the U.S. Geological Survey. “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.”