Study On Three-dimensional Hydrodynamic And Suspended Sediment Transport And Diffusion Characteristics Before And After Yushan Reclamation Project

The trend of economic development in coastal areas is obvious.The shortage of land resources and the contradiction of land use have become the main two factors restricting economic development.Under the circumstances,reclamation works construction could be a solution.Large-scale reclamation projects will inevitably lead to some changes in the hydrodynamic environment of the project sea area.Therefore,studying the hydrodynamic characteristics and sediment diffusion of the engineering sea area can effectively plan the operation of the waterway,make sufficient preparations for ensuring the safety of the waterway,and also provide a good reference for similar reclamation projects.In this thesis,the Mike 3 hydrodynamic coupled suspended sediment transport model is established for the green petrochemical based on the reclamation project of Dayushan Island in Zhoushan sea area,and is compared with the two-dimensional model in detail.On the basis of reliable model,the overall influence of reclamation project on hydrodynamic environment and sediment distribution of engineering area and surrounding sea area before and after construction is simulated and analyzed.The results show as these:(1)The shoreline angle caused by the construction of the embankment has a certain degree of influence on tidal current movement.The tidal surge on both sides of the west and southeast dikes is deflected,at the same time,the velocity weakening degree is increased.The hydrodynamic characteristics of the dike corner on the south side of Yushan Island and both ends of the southeast dike are obvious.(2)After the project,the average sediment concentration of Yushan Island tends to be more in the east and less in the west,and the sediment concentration gradually increases from the embankment to the surrounding sea.The sedimentation area is mainly concentrated in the southeast.The annual sedimentation thickness is between 1～2.2 m.(3)The southwest side of the south sea are basically scoured.The construction of the dike makes the water flow in this part concentrated,which leads to the high velocity in the area to drive the sediment to start.The scour degree is not large,and the annual scour thickness is between 0.2～1 m.(4)In terms of the change of scouring and silting,the construction of the reclamation dike has little influence on the scouring and silting distribution of Yushan project and adjacent sea area,and the influence areas are concentrated near the front of the dike and the back flow area caused by the dike,that is,the area with the increase of the velocity of the dike has a large degree of scouring,and the area with the decrease of the velocity of the dike has a serious silting.The research in this thesis can provide a basis for the construction of Yushan Island green petrochemical phase 3 project in Zhoushan,and can also be extended to the study of water and sediment in the multi-island sea area similar to the hydrodynamic environment of Zhoushan,which has certain reference value.