HR: 0800h
AN: GC41A-0107    [Abstracts]
TI: The Influence of Climate Change on Headwater Stream Discharge in the Southern Sierra Nevada (1957-2007)
AU: * Whitaker, T W
EM: twhitaker@fs.fed.us
AF: USDA Forest Service, Pacific Southwest Research Station, 2081 E Sierra Ave, Fresno, CA 93710,
AU: Hunsaker, C T
EM: chunsaker@fs.fed.us
AF: USDA Forest Service, Pacific Southwest Research Station, 2081 E Sierra Ave, Fresno, CA 93710,
AB: The Sierra Nevada Mountains are of critical importance to water availability for the State of California. Historically, the winter snowpack has acted as a natural reservoir of fresh water throughout the winter months when a majority of the precipitation falls in the state. With the onset of spring snow melt, the water in the snowpack is released and made available to the remainder of California over the dry summer months. As a result of global climate change, warmer temperatures on the order of 2-5 °C are predicted for California over the next century. This will lead to diminished winter snow cover and the onset of an earlier release of the snowpack making significantly less water available during the summer period. We use the long-term historical discharge and precipitation records (1957-2007) from the Teakettle Experimental Forest (Teakettle) to evaluate whether the hydrological effects of climate change are already evident on small, headwater systems in the southern Sierra Nevada. Additionally, the long-term pattern from Teakettle is compared to the past five-year record from 10 recently instrumented headwater systems in the Kings River Experimental Watershed (KREW). Teakettle is an unmanaged old-growth forest while the other watersheds are actively managed. At an elevation of 2050 m to 2450 m, winter precipitation on Teakettle is snow dominated. However, winter rain events at this elevation do occur in the southern Sierra Nevada. The KREW watersheds, including Teakettle, extend across the rain-snow interface boundary (1485 m to 2500 m) where winter precipitation may fall as either rain or snow. This provides a good opportunity to observe whether the number of winter rain events on the Teakettle watershed is increasing and what role this may play in the distribution of annual runoff. The historical record also allows us to evaluate any potential changes in the timing of spring snow melt and the effects climate change may have on annual discharge totals.
DE: 1637 Regional climate change
DE: 1807 Climate impacts
DE: 1854 Precipitation (3354)
DE: 1860 Streamflow
DE: 1879 Watershed
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting