The Cohesive Sediment Transport In The Yangshan Port And The Study On The Profile Shaping Process

The transport of cohesive sediment based on the flow conditions was an essential part of Coastal Hydrodynamics. In systematic review, we are lacking of the achievement which can apply to project planning and design directly. In the period of project planning, we can't find the general conclusion which can be applied to calculate the amount of silt deposit in the whole sea region . in the second period of design and project construction , we can't estimate or calculate topographical change and in advance. Sediment problems have become an important issue and received extensive attention of scholars.We use the DHI MIKE21 model to study the hydrodynamics and sediment transport in the Yangshan port. First, a hydrodynamic model with the larger computational domain covering Hangzhou Bay and the Changjiang River Estuary was constructed to study the general characteristics of hydrodynamics and provide the hydrodynamic information as the boundary conditions in the following modeling of sediment transport with the smarter mesh sizes in the Yangshan port. Second, the models were validated by measurements, computed tidal level and current are in good accordance with the measured data. The computed suspended sediment concentration at different locations are also matched the field data generally. In sum, the characteristics of hydrodynamics and sediment transport in the Yangshan port are studied briefly based on the modeling results. The primary conclusions:(1) Blanking off the Kezhushan inlet won't conduce to terrain change and flow field change severely in the region under 30m water depth .(2) By comparing the post-reclamation current fields with the pre-reclamation ones, we detected differences that the single state of flood tide dominated the field has been changed. The result further indicates that in the south port the ebb tide began to dominate the field strongly and in the north port the flood tide rised further.(3) Based on the contrast of computation tidal flow capacity and the eroding tendency in the Kezhushan inlet, the existence of the inlet can help to keep the current eroding tendency.(4) We used the valid model to analyze the project plan of separating region and whole region . The whole region plan will help to increase the dynamic of ebb tide and contribute to silting in the silted region. (5) How far will the silted region goes? From the analysis of coastal profiles under the 30m water depth, the silted region will remain steady. But the some specified silted district will aggravate the silting condition.(6) This dissertation meets Tiankesuo's consequences in the cause of formation of silting areas in the south of port and finds some differences with the consequences in the middle of port.(7) In terms of sediment accumulation ,we suggest to keep the Kezhushan inlet.