HR: 0800h
AN: H51E-0790    [Abstracts]
TI: Sediment Fluxes from California Coastal Rivers: The Influences of Climate, Geology and Topography
AU: * Andrews, E D
EM: eandrews@usgs.gov
AF: U.S. Geological Survey, 3215 Marine Street, Boulder, Co 80303, United States
AB: Annual suspended, bedload and total sediment fluxes were determined for 17 river basins draining the west flank of the California Coast ranges. The river basins have hydrologic records covering all or most of the period, 1950- 2006, and were selected to be relatively unaffected by flow storage, regulation, and depletion that alter the downstream movement of water and sediment. Relatively large annual sediment fluxes, S_f, are strongly influenced by the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). The frequency of relatively large S_f, during La Niña (El Niño) phases decreases (increases) from north-to- south. The influence of ENSO is modulated over a period of decades by the PDO, such that relatively large S_f, during La Niña (El Niño) phases are more frequent in conjunction with cool PDO (warm PDO). Mean annual S_f were regressed against basin and climatic characteristics. Basin area, bedrock erodibility, basin relief, and precipitation explain 95.5 percent of the variation in mean annual S_f from the 17 river basins. Bedrock erodibility is the most significant characteristic influencing mean annual S_f. Basin relief is a superior predictor of mean annual S_f compared to basin slope. Mean annual S_f is nearly proportional to basin area and increases with increasing precipitation. For a given percentage change, basin relief has a 2.3 fold greater effect on mean annual S_f than a similar change in precipitation. The estimated mean annual S_f from all California coastal rivers for the period 1950-2006 would have been approximately 130 million without flow storage, regulation, and depletion.
DE: 1807 Climate impacts
DE: 1862 Sediment transport (4558)
SC: Hydrology [H]
MN: 2007 Fall Meeting