San Timoteo Creek, California, Sedimentation Study. Numerical Model Investigation of In-Channel Sediment Basins
ARMY ENGINEER DISTRICT LOS ANGELES CA
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The U.S. Army Engineer District, Los Angeles, proposed channel improvements to the San Timoteo Creek, San Bernardino County, California. Because the watershed involved has the potential to supply a large amount of sediment during a storm event, debris basins were required to assure that the proposed channel would function as designed. The traditional dam-style debris basin design was aesthetically unacceptable to local residents, and the local flood control agency raised concerns about dam safety. Thus, a series of six in- channel sediment basins was designed. The series of basins was designed to fill equentially with the total sediment storage capacity sufficient for expected needs. The conceptual design of the basins was unproven so detailed analyses were required to verify the design. This was accomplished using the numerical models TABS1 HEC-6 and SAM. TABS1 was able to simulate sequential filling of the basins, the variation of deposition rate as each basin filled, the size class distribution of the sediment that passed through the basin, and the slope of the deposited sediments. A series of sensitivity test were conducted to verify the design given the lack of measured prototype data. Overall results concluded that the in-channel basins performed satisfactorily for a relatively wide range of conditions. This methodology for sedimentation design is unique and provides an approach that may be generalized to other flood control channel projects.
- Hydrology, Limnology and Potamology
- Civil Engineering