NASA researchers estimated it will take 11 trillion gallons of water to get California out of the devastating drought conditions that have swept the state; this is 1.5 times the maximum volume in the largest U.S. reserve.
The findings were made using space and airborne measurements taken by NASA.These reading provided insight into key features of the California drought. Data from NASA's Gravity Recovery and Climate Experiment (GRACE) satellites was used to develop the first-calculations showing the volume of water required to end a drought episode.
"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 Jay Famiglietti of NASA's Jet Propulsion Laboratory. "That's an incredible advance and something that would be impossible using only ground-based observations."
The GRACE data revealed that since 2011 the Sacramento and San Joaquin river basins decreased in volume by four trillion gallons of water annually, which is more than what is used by California citizens for municipal purposes as a whole. Data from NASA's Airborne Snow Observatory taken this year also show snowpack in California's Sierra Nevada is only half of what has been previously estimated.
"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 new drought data also showed groundwater levels across the U.S. Southwest are in the lowest 2 to 10 percent seen since 1949. The researchers noted that while recent storms have made California a little bit wetter, it is not enough to recover the land from the multi-year 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," Famiglietti said.
The findings were presented by NASA scientists Dec. 16 at the American Geophysical Union meeting in San Francisco
