Western drought causes Earth's surface to rise as water levels drop
A year and a half of drought has depleted 63 trillion gallons of water across the Western United States, according to a new study that documents how the parched conditions are altering the landscape.
The loss of groundwater, as well as surface water such as reservoirs, has been so extreme that it lifted the West an average of one-sixth of an inch since 2013, according to researchers from UC San Diego's Scripps Institution of Oceanography and the U.S. Geological Survey.
The situation is even worse underneath the snow-starved mountains of California, where the Earth rose up three-fifths of an inch. Groundwater is very heavy, and its weight depresses the Earth's upper crust. Remove the weight, and the crust springs upward.
The study, published online Thursday by the journal Science, showed how a lack of rain and snow cut water levels first in the U.S. Southwest and Central and Southern California before spreading into Oregon and Washington state. Water naturally evaporates, is absorbed by plants and is pumped by humans, so levels go down if the water is not replenished.
"The thing that is exceptional about this drought is that it really covers the entire region" of the Western U.S., said Scripps assistant researcher Adrian Borsa, the study's lead author. "I can't tell you whether this is as big as earlier droughts, but I would say within the last 10 years, this is definitely an unprecedented change with this drought."
The lost water is equal to a 4-inch layer of water across the United States west of the Rocky Mountains, according to the study.
