Jet scouring of ambient sediment in the outfall of stage 2 Shanghai Sewerage Project

The outfall of the Stage 2 Shanghai Sewerage Project will be constructed in the Bailong Gang zone of Yangtze Estuary where the sediment content is high and the water depth is shallow. Lowering the port height above river floor as far as possible to fully utilize the depth of receiving water is one way to increase the near field dilution, but doing so will increase the possibility of the sediment deposition over the diffuser. Based on the theories of model similarity and sand movement, experiments on the jet scouring of ambient sediment are conducted under both the conditions that there is sediment deposited over diffuser and the ambient current is sediment-laden. The ability of scouring ambient sediment for every feasible scheme is analyzed when the port height is lowered.