Numerical Simulation On Hydrodynamic Environment Effects Of Reclamation Projects In The Changxing Island

The utilization of marine resources has always been the focus of marine workers in China.With the development of economy and society and the advancement of scientific research,reclamation projects have become more and more popular and have become one of the most important methods for alleviating land use conflicts.However,due to the lack of long-term planning and unstandardized construction of the sea project,the coastline and Marine ecological environment have suffered great damage.In order to solve this problem,this paper selects the reclamation project of Changxing island in Dalian as the basis to simulate and analyze its influence on the surrounding water environment.In this paper,the development of the offshore reclamation project and the research progress of hydrodynamics and water quality model are summarized in detail,and then the project and simulation methods are introduced.First,In the first part,the three-dimensional baroclinic water model of Bohai sea is constructed.,through the twelve tide level stations,four current stations and four thermohaline stations compares the simulated data and the measured data,we can find that the results of model simulation is good;According to the well-validated Bohai Sea large scale model,the small-scale model of the sea near Changxing island in Dalian was constructed,and the influence of the reclamation project on the surrounding water environment was simulated based on the small-scale model.The study found that the trend of high spring tides in the sea near Changxing island,as well as the flow direction of Huludao and Fuzhou bay,is mainly from the N direction to the NE direction;And in the southern part of the Pulandian bay,the trend is mainly from the NW direction to the N direction;There are many coves near Changxing island which are too long and narrow,so the water exchange capacity in these bay is low.Salinity distribution,salinity is lower near the coast,this is because of the high salinity of the water off the coast and there are rivers and other confluences along the coast,but the salinity is high in the gourd valley in central and southern Pulandian bay because the bay is too long and narrow and the water exchange ability is very weak.In terms of water quality,the simulated results show a good reappearance of the spring water bloom and autumn water bloom in the Bohai Sea;According to the regeneration mechanism of nutrient salt and photosynthesis of phytoplankton,the changes of inorganic nitrogen and phosphate were analyzed.Finally,this paper analyzes the influence of the reclamation project of Changxing island on the surrounding water environment from the aspects of flow field,salinity field and water quality,and draws the following conclusions: The tidal level and flow velocity of the tidal flow field will change greatly,the maximum change rate of tidal level at flood in spring tide is 3.83%,and the maximum change rate of tide level at ebb is 6.34%;The maximum rate of tidal current flow change rate at flood in spring tide is 38.64%,and the maximum value of tidal current velocity change rate is 19.79% at ebb.The salinity contour of the project will change to a certain extent,and the area of the high salinity area will also change.There is also a significant change in the composition of nutrient salts,such as the significant increase in inorganic nitrogen content,the change of phosphate is a more tortuous process,the ratio of nitrogen and phosphorus is an increasing state,but the area near the Changxing Island is still in a state of nitrogen limitation.