Study On Water Quality Simulation And Risk Diffusion Prediction In Daya Bay,Shenzhen

As the main area for the exchange of materials between land and sea,the bay is the main region of the human economy and growth.The water pollution in the rivers and seas in these regions has always been a limiting factor in the management of water environment.Daya Bay in Shenzhen is one of the important bays in Guangdong Province.However,the environmental problems caused by its water pollution have a serious impact on the region and the comprehensive treatment of which in Daya Bay has also been a major concern.By establishing a numerical model of water environment and exploring the phenomenon of water movement in Daya Bay,the corresponding emergency strategies for water quality assessment,water environment information management,and response to sudden water pollution accidents can be established.Such models help to protect the marine ecological environment and rationally utilize the marine ecological resources of Daya Bay.This paper introduces several models commonly used in numerical simulation of hydrodynamics.The three-dimensional numerical model is commonly used in the Gulf Estuary area.Among these,the Environmental Fluid Dynamics Code(EFDC)model is widely used.Based on the results of previous studies on the river pollution load in Daya Bay basin,the EFDC model is applied to establish a hydrodynamic simulation and risk diffusion prediction model for Daya Bay.The Daya Bay water environment model is developed based on the EFDC model.The simulation results of the hydrodynamic process and water quality indicators are consistent with the measured results,indicating that the model can be used to analyze and predict the water environment changes in the Daya Bay.The model can be used not only to simulate the distribution of hydrodynamic processes and major pollutants in Daya Bay over space and time but also to simulate and analyze sudden pollution accidents to guide the range and time of affected targets in sensitive areas.The comparison between the simulation results of the main water quality indices and the measured data shows that the model has good prediction power.Under the existing conditions,the water quality indices exceed the standards,which are mainly concentrated near the mouth of the river with weak hydrodynamic force,such as Fanhe Port,Dapeng Harbor,and Yaling Bay.However,water pollution in the middle of the sea area is relatively small,and the concentration of water quality indices has a negative correlation with the tides.Under various wind conditions,the aquatic resources in central area of Daya Bay is the most affected by oil spills,which can disperse and pollute within 2 hours.Because of the weak hydrodynamic exchange in Daya Bay,the main way to improve the quality of the water environment in this area is the control of pollutants entering into the sea.