Sediment deposition analysis of downstream access channel of permanent ship lock during 135m operational phase of Three Gorges reservoir

Based on the abundant data of the sediment deposition and water-sediment factor change in the downstream access channel and entrance area of the permanent ship lock during 135m operational phase,a series of parameters and relationships are analyzed.These parameters include the deposition quantity and its distribution,the deposition configuration of entrance bar,the deposition mechanism and the rermval time of sediment.Then,some relational equations are established,such as sediment concentration between the entrance and the Yangtze River,inclined flow velocity of the entrance and discharge of the Yangtze River,the aggradation and the incoming sediment of entrance bar.And,the deposition of the density and circulation flow in the downstream access channel and entrance area are verified by the inverted density flow theory.The results indicate that the depositions in the downstream access channel and entrance area develop mainly in the major flood period (Jul.-Sept.),and one desalting in the later flood stage (Oct.-Dec.)can satisfy the shipping depth demand.