December 10, 2013
NASA Tech Helps California Meet Water Needs During Drought
[ Watch the Video: Airborne Snow Observatory: Measuring Snowpack from the Sky ]
redOrbit Staff & Wire Reports - Your Universe Online
It might have been the driest year ever recorded in California, but thanks to NASA, the millions of people who call the San Francisco Bay Area home had plenty of water this summer, the US space agency said Monday during a media briefing at the 2013 American Geophysical Union (AGU) Fall Meeting.
NASA’s prototype Airborne Snow Observatory mission helped water managers in the region achieve near-perfect water operations over the summer, the agency said in a statement. The high-resolution snow maps produced showing the Tuolumne River Basin in the Sierra Nevada helped officials optimize reservoir filling and hydroelectric power production at the Hetch Hetchy reservoir and the O’Shaughnessy Dam.
As a result, the reservoir was full at the end of the snowmelt season, there was no water spillage, and nearly $4 million worth of hydropower was generated, scientists from NASA, the University of Washington and McGurk Hydrologic Associates said during the media briefing. The collaboration is a three-year demonstration project between NASA’s Jet Propulsion Laboratory (JP) and the California Department of Water Resources.
“For the first time, Airborne Snow Observatory data are telling us the total water in the snowpack in the watershed and the absorption of sunlight that control its melt speed, enabling us to estimate how much water will flow out of a basin when the snow melts,” explained Tom Painter, the observatory principal investigator at JPL and an adjunct professor of geography at UCLA.
“By combining near-real-time information on the total amount of water in the snowpack with observations of water inflow to Hetch Hetchy reservoir between April and July, we were able to greatly improve the model we developed to predict inflow into the reservoir,” he noted, adding that this allowed reservoir managers to more efficiently distribute water inflow among power generation, water supply and ecological purposes.
Painter said that the higher-quality snowpack measurements and the more efficient reservoir operations will prove to be valuable assets as the community (and the rest of the world) has to deal with global warming, uncertain weather, continuing drought conditions throughout the state and an ever-growing demand for water.
The Airborne Snow Observatory is stationed on board a Twin Otter aircraft, and it measures snow depth and snow reflectivity – the two properties most essential to understanding snowmelt runoff, NASA said. By combining snow depth and estimated density, snow water equivalent (or the amount of water contained in the snow) can be derived and then used in order to determine how much water will run off.
“Snow reflectivity, or albedo, is the fraction of the incoming amount of sunlight reflected by snow. Subtracting reflected sunlight from incoming sunlight gives the absorbed sunlight, which largely controls the speed of snowmelt and timing of its runoff,” the agency explained.
Previously, Tuolumne River Basin runoff forecasts were made using monthly ground snow surveys and daily automated measurements at lower or middle elevations. However, when snow melted in those locations, an unknown amount of snow remained at higher elevations. The observatory was able to measure snow in an area 46 million times larger than that covered by the survey sites, according to the researchers.
“Snow controls high-elevation streamflow and ecosystems, but we’ve historically had to guess how much snow fell and where it was stored,” said Jessica Lundquist, an associate professor at the University of Washington. “With these data, we can improve how we model mountain systems and predictions of how those systems will change in time… To me, the Airborne Snow Observatory snow maps are cooler than pictures from Mars.”
“The Airborne Snow Observatory is an innovative use of NASA advanced sensor research applied to one of the top challenges our nation and our planet face: freshwater management and practical water management information needs,” added Brad Doorn, program manager in Applied Sciences at NASA Headquarters. “The observatory is also advancing our scientific understanding of Earth processes and how we can better monitor them in the future, from both air and space.”