ABSTRACT
This chapter deals with sediment flushing systems at the water intake. It outlines the principles governing the elimination of sediment, and the effect of the reservoir on the overall project. The chapter considers the periodic flushing of a low-velocity reservoir created by the water offtake dam itself. With a continuous flushing system, once significant bed load occurs, the reservoir depth is dropped to provide enough tractive force to entrain the material to the dam and the intake. Two kinds of efficiency need in fact to be distinguished—hydraulic efficiency and economic efficiency. Such a situation combines the hydraulic efficiency of periodic flushing with a satisfactory economic efficiency. To make periodic flushing possible, the reservoir should be large so that the frequency of flushing is not so high as to overly disturb normal operation of the intake. The chapter reviews sediment-sluice arrangements, describes designs suitable for relatively high discharges, as at Lavey and Donzere-Mondragon, and discusses feasible solutions for low discharge situations.
