Enhanced hydrosuction performance for cohesive sediment removal in low-head reservoirs

Deposited sediment removal or dredging is generally required in many hydro-system projects. Siphon dredging or hydrosuction bears many advantages including low energy consumption, minor turbidity generation and ability of localized dredging. A new device attached to a regular siphon inlet is introduced which produces a swinging action by means of a simple mechanism. Equipped siphon sweeps a larger area than what a regular siphon does and enhances the hydrosuction performance for cohesive sediment removal. Regular and equipped siphon performances for dredging non-cohesive and cohesive sediments were investigated experimentally. Time to reach equilibrium scour was determined and applied for all the tests. The equipped siphon generated larger scour holes in cohesive sediment type than that of the regular one and enhanced sediment removal process. This could be attributed to the swinging action of the siphon inlet which strikes the scour hole wall and acts against the cohesion property of the sediment.