Flushing sediment through reservoirs

The control of reservoir sedimentation through hydraulic flushing has been employed in several parts of the world to sustain the useful storage capacity of the reservoirs. However, no comprehensive analysis has been conducted to understand the sediment flushing processes. In this study, laboratory experiments were performed to investigate the flushing processes during drawdown flushing, including outflow sediment discharge, characteristics of the flushing channel and flushing effectiveness. From both laboratory and field data, it is found that outflow sediment discharge can be well related to a hydrauic parameter which is a function of outlet discharge, water-surface gradient and flushing channel width. It is also found that flushing efficiency increases dramatically when retrogressive erosion emerges. A geomorphic relationship is used to estimate the equilibrium width of the flushing channel. A 1-D diffusion model presented herein is employed only to simulate the general trend of bed profile evolution an...