Abstract: Since the impoundment of Three Gorges Project and its upstream cascade reservoirs, the sandy bed of Jingjiang River has been scoured and lowered by 3m 6m, which brought about negative effect on revetment works, water supply projects, as well as the flow sediment diversion from three diversion channels into Dongting Lake. The aim of this research is to control the scouring in Jingjiang River and to stabilize or control the decrease of low water level by analyzing knick point control schemes. On the basis of numerical simulation results, it’s proposed that the riverbed protection or the riverbed protection combined with submerged dikes could reduce erosion in the Jingjiang River, lessen or stop water level lowering, and relief the decrease of flow sediment diversion from the three diversion channels. However, the proposed regulative projects have certain influence on the morphology of the downstream reach from Chenglingji to Hankou, which should be addressed in the future.

Key words: riverbed downcutting, water level lowering, knick point control project, efficiency and effects of regulation project