In early August, the U.S. Drought Monitor confirmed that California is experiencing the most severe drought since the agency began keeping records. The water shortage has persisted for three years and today over 58 percent of the state is in the midst of “exceptional” drought – the highest of the five drought categories. Over 80 percent of the state is in “extreme” drought (the fourth highest listing) and last week over 99 percent of the state was in “severe” drought (the third highest).
This month the San Gabriel Mountains near Los Angeles experienced rains heavy enough to trigger mudslides and flash floods, but Richard Tinker, a drought expert with the federal government’s Climate Prediction Center, says these storms were merely “a drop in the bucket.”
“Any rain this time of year – while a bonus – doesn’t really have much of an effect on the drought,” he added.
California’s three largest reservoirs – Trinity Lake, Lake Oroville and Lake Shasta – are at approximately 30 percent capacity, according to the Los Angeles Times, and most state reservoirs are down to 59 percent. This is still better than the statewide average of 41 percent during the 1977 drought, says Ted Thomas, a spokesman for the California Department of Water Resources.
Even so, researchers at the Scripps Institution of Oceanography at UC San Diego have made an alarming geologic discovery. Using GPS data, they found that California’s current water deficit (nearly 240 gigatons or 63 trillion gallons) has actually caused the land to rise up “like an uncoiled spring.”
Without water, snow and ice to weigh them down, California’s mountains have risen a little over half an inch. The west in general has risen 0.157 inches.
“Groundwater is a load on the Earth’s crust,” says Klaus Jacob, a seismologist at Columbia University’s Lamont-Doherty Earth Observatory. “A load compresses the crust elastically, hence it subsides. When you take that load away (by the drought) the crust decompresses and the surface rises. From the amount of rising, one can estimate the amount of the water deficit.”
The Scripps study was published in the journal Science on Thursday. “These results quantify the amount of water mass lost in the past few years,” says Dan Cayan, one of the study’s researchers. “It also represents a powerful new way to track water resources over a very large landscape.