Sedimentation Study and Flume Investigation, Mission Creek, Santa Barbara, California; Corte Madera Creek, Marin County, California

摘要

A concrete-lined supercritical-flow flood-control channel was designed for Mission Creek in Santa Barbara, California. The design did not include a debris basin at the upstream end of the channel, so there was potential for a significant quantity of bed load to be delivered during a flood event. An existing concrete-lined flood control channel on Corte Madera Creek in Marin County, California lacks a debris basin at its upstream terminus and carries significant bed load through a supercritical flow reach. This study was conducted to determine the influence of potential bed load transport on hydraulic roughness in the concrete-lined channel. For Mission Creek, a numerical sedimentation model study was conducted to determine the quantity and size of bed load transport that would occur during a flood event. flume studies, which simulated flood unit discharges in Mission Creek and Corte Madera Creek were conducted to determine hydraulic roughness due to bed load transport. An equation was developed that accounted for the additional hydraulic roughness due to bed load transport in concrete channels. The equation is applicable for gravel concentrations up to about 3,000 mg/l, which is the concentration where sediment began to accumulate on the bed.