Sediment delivery in a semi-arid coastal stream

Abstract

The transport and yield of bed sediment in a small coastal stream is the focus of this study. Spatial and temporal variations of sediment characteristics have been simulated using a calibrated mathematical model for time-dependent fluvial process-response. The study illustrates how channel storage, a major factor affecting sediment yield, can be quantified by an erodible-boundary model. The mathematical model also accounts for the storage effects caused by the works of man, a task that cannot be easily accomplished by other methods. The model simulates the interrelated changes in channel-bed profile and channel width based upon the stream's tendency to seek uniformities in sediment discharge and power expenditure. Scour and fill of the channel bed are accompanied by significant changes in channel width, which may contribute more to sediment storage. Thus, sediment routing must be based upon an erodible-boundary model rather than an erodible-bed model. This study confirms field evidence of the significant variation in sediment yield that occurs along the stream reach.