Effects of Climate on Snowmelt and Water Availability for Reservoirs in the Southern Sierra Nevada

Science Center Objects

Potential changes in air temperature and precipitation due to changes in climate may result in more variable or smaller snow packs and earlier snowmelt in the southern Sierra Nevada in upcoming years. These conditions are likely to result in increased difficulty in planning reservoir operations for hydroelectric power and water availability during springtime snowmelt in this region. Reservoir operations are intended to optimize the volume of water available throughout the summer as well as provide ample storage for rapid snowmelt that could overfill the reservoirs requiring the release of excess water downstream in floodplains. Anticipating the snowmelt conditions, as well as higher altitude rain events, could provide the opportunity for early releases to provide room for excess snowmelt, or the ability to allow for optimum storage for summer use.

Map of study area, including 5 river basins and 6 reservoirs in the southern Sierra Nevada

Map of study area, including 5 river basins and 6 reservoirs in the southern Sierra Nevada

(Public domain.)

Objectives: The objectives of this proposed study are to (1) develop the modeling tool necessary to characterize the hydrologic processes relevant to snowmelt runoff in Sierra Nevada basins sensitive to changes in climate, (2) calibrate the model specifically to 5 southern Sierra basins (Tuolumne, Merced, San Joaquin, King and Kaweah basins; Figure 1), and (3) provide correction factors for the DWR predictive model that uses the Snow-17 algorithm, to account for radiation in the 5 basins for use in anticipating springtime basin runoff relevant to reservoir storage and operation.