HR: 0800h
AN: H51C-0382    [Abstracts]
TI: Sediment Delivery From Chronic Slope Failures, Thomes Creek, California
AU: * Gauthier, A J
EM: dahli1@netzero.com
AF: Department of Geological & Environmental Sciences, California State University, Chico, Chico, CA 95929-0205 United States
AU: Hoover, K A
EM: khoover@csuchico.edu
AF: Department of Geological & Environmental Sciences, California State University, Chico, Chico, CA 95929-0205 United States
AB: Estimating the volume of sediment delivered to a stream channel from chronic slope failures requires a combination of sequential aerial photograph analysis, field examination of mass wasting locations and sediment delivery modes, and slope stability modeling considerations. We applied these analysis methods to quantify the sediment delivered from failures in the Thomes Creek watershed, located on the western side of the Sacramento River valley in Northern California. Thomes Creek is one of the highest sediment producers in the western United States as a result of high relative relief, unstable geology and steep slopes in the upper watershed. Sediment is delivered to the stream from debris slides fed by large rotational slides located upslope. Photographs of the upper watershed spanning a period from 1952 to 1998 indicate that the number of active debris slides steadily increased after 1952, probably as a result of land-use practices, primarily timber harvesting and road building. The number of active slides peaked at 110 in 1988 and has fluctuated between 70 and 100 since. Based on volumetric analysis spanning a ten-year period between 1988 and 1998, these slides are estimated to deliver 89,700 cubic yards of sediment to the Thomes Creek channel annually. This estimate is supported by a slope stability analysis conditioned on precipitation records for 1989 through 2004, which suggest that an average 86,900 cubic yards of sediment may be delivered to the channel each year.
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1815 Erosion
DE: 1826 Geomorphology: hillslope (1625)
SC: Hydrology [H]
MN: Fall Meeting 2005