Numerical Study On The Influence Of The Forebay Reclamation On Sediment Distribution And Pollutant Transport In The Jiaozhou Bay

Jiaozhou Bay is a small partly-closed coastal waterbody with a large area of intertidal zone, and It plays an important role in the economic development of the surrounding area. In recent years, a number of reclamation were launched in the Jiaozhou Bay to meet the demand of social economy development, especially in the forebay, multiple terminal expansion projects were carried out. However, the reclamation will change regional hydrodynamic structure, topography, and so on, then it can affect the movements of the regional waterbody and the dynamic environments of pollutant movement, thus the behavior of pollutant movement and the regional water environment evolution process will be changed.The 3D numerical model of Jiaozhou Bay tide current and sediment with dynamic boundary are established by using the ECOMSED model and dry-wet point method. Then the variation rules of tidal current field and sediment concentration before and after the forebay reclamation in the Jiaozhou Bay are simulated. Based on the developed tide current numerical model and the Lagrangian particle tracking technology, the pollutant transport before and after the forebay reclamation in the Jiaozhou Bay are simulated by tracking the movement of single particle and particles swarm. By comparing with the trajectory of pollutant before and after the forebay reclamation, the influence rules and scope of the forebay reclamation on pollutant transport in the Jiaozhou Bay are analyzed。we can draw the following conclusions:(1) The model established in this paper are well verified, it shows that the tidal current field and sediment concentration in the Jiaozhou Bay can be well simulated by using the model.(2) The topography in the forebay area will be changed after the reclamation, then water that entering into forebay and Haixi bay will be reduced, and the increase in depth also increases the loss of tidal wave energy which lead to a reduction of tidal level and current velocity in this area. However, due to shortening the distance between Tuandao and Xuejiadao, the flow velocity here is increased. The reclamation also prevents current from flowing into Jiaozhou Bay which causes a little decreases of the current velocity near the project area. And the decrease of flow velocity weakens the ability of the sediment resuspension which leads to the reduction of the sediment concentration in these areas. However, the tidal level, current velocity and sediment concentration in other areas of the Jiaozhou Bay do not change much.(3) The hydrodynamic environment in the forebay area is changed by the reclamation, thus the number of pollutants that enter into forebay are increased and the number of pollutants that enter into Haixi bay are reduced, which will worsen the pollution of forebay. However, the influence of the forebay reclamation on pollutant transport in the Jiaozhou Bay are limited in scope, and it only has greater influence on the area around the reclamation.