NASA: California Needs 11 Trillion Gallons of Water to End Epic Drought
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Now groundbreaking new calculations based on Now groundbreaking new calculations based on NASA satellite data have revealed just how large that deficit is. A team of sci's Jet Propulsion Laborator (JPL) crunched data from NASA's Gravity Recovery and Climate Experiment (GRACE) to figure out how much water it would take to end the drought. They determined that it would take 11 trillion gallons—about 1.5 times the maximum volume of the largest U.S. reservoir—to make up for drought losses due to record heat and low rainfall.
"Spaceborne and airborne measurements of Earth's changing shape, surface height and gravity field now allow us to measure and analyze key features of droughts better than ever before, including determining precisely when they begin and end and what their magnitude is at any moment in time," said NASA team leader Jay Famiglietti. "That's an incredible advance and something that would be impossible using only ground-based observations."
The NASA team found that the volume of water in the Sacramento and San Joaquin river basins had decreased by 4 trillion gallons a year since 2011—more water than is used by the state's residents each year for domestic and municipal purposes—and that water storage in the two basins is currently 11 trillion gallons below normal, a deficit that has steadily increased since GRACE launched in 2002. Depletion of groundwater in California's fertile agricultural Central Valley is responsible for two-thirds of the loss.
"Integrating GRACE data with other satellite measurements provides a more holistic view of the impact of drought on water availability, including on groundwater resources, which are typically ignored in standard drought indices," said Matt Rodell, chief of the Hydrological Sciences Laboratory at Goddard.
Making matters worse, data from NASA's Airborne Snow Observatory earlier this year showed that California's Sierra Nevada snowpack was half that of earlier estimates.
"The 2014 snowpack was one of the three lowest on record and the worst since 1977, when California's population was half what it is now," said Airborne Snow Observatory principal investigator Tom Painter of JPL. "Besides resulting in less snow water, the dramatic reduction in snow extent contributes to warming our climate by allowing the ground to absorb more sunlight. This reduces soil moisture, which makes it harder to get water from the snow into reservoirs once it does start snowing again."
The NASA scientists said that the recent rainstorms in California will do little to alleviate the water shortage, failing to provide anything close to the amount of water the state needs to end its prolonged drought.
"It takes years to get into a drought of this severity, and it will likely take many more big storms, and years, to crawl out of it," said Famiglietti.
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