Even with this winter's strong El Niño, the Sierra Nevada snowpack will likely take until 2019 to return to pre-drought levels, according to a new analysis led by UCLA hydrology researchers. Additionally, they suggest their new method, which provided unprecedented detail and precision, could be useful in characterizing water in the snowpack in other mountains, including ranges in western North America, the Andes or the Himalayas. These areas currently have much less on-site monitoring than in the Sierra Nevada.

The study was published online today in The American Geophysical Union journal Geophysical Research Letters.

"With the consecutive years of ongoing drought, the Sierra Nevada snowpack's total water volume is in deficit and our analysis shows it will to take a few years for a complete recovery, even if there are above-average precipitation years," said the study's principal investigator, Steve Margulis, professor of civil and environmental engineering at the UCLA Henry Samueli School of Engineering and Applied Science.

Much of California's water comes from the when the Sierra Nevada snowpack melts. The winter of 2015 capped four consecutive years of drought that resulted in the largest cumulative drought deficit spanning the 65 years that have been examined. The water volume of the snowpack in 2015 was just 2.9 cubic kilometers, when a typical year is about 18.6 cubic kilometers.

"It is critical for regions like California, that rely on their regional snowpack for water supply, to understand the dynamics of the system," Margulis said. "Our new tool could help not just California, but other regions, gain insight about their regional snowpack."