Numerical Simulation Of The Behavior And Fate Of Marine Oil Spill And Its Application In Jiaozhou Bay

In recent years,with the increase of offshore oil field facilities,oil leakage accidents will surely pose a potential threat to marine environment.Because of unpredictability of oil spill,it will seriously destroy the marine ecosystem,and even greatly threaten human health without timely treatment.Therefore,based on numerical simulation and theoretical analysis,this paper systematically studied the behavior and fate of marine oil spill and its flowing mechanism,which is necessary for controlling the development trend of accident and making some protective contingency measures.This paper bases on the high-precision measured coastline and water depth data of Jiaozhou Bay.The unstructured triangular grids in FVCOM were generated by SMS,and water depth was interpolated into the grids by using inverse-distance weighting method.Based on the finite-volume coastal ocean numerical model(FVCOM),a three-dimensional shallow-sea tidal model was established for Jiaozhou Bay,which was used to calculate the tides and currents in the bay.The results show good agreement with the measured data and can be provided for oil spill simulation as the basic environmental data.An interface was created by using Fortran language programs to connect hydrodynamic model with oil spill model.Considering currents and real wind,the 2D oil spill numerical model was built to forecast the fate and behavior of spilled oil.In order to increase the accuracy of the model calculation,two key parameters,including dispersion coefficient and the amount of oil-particles,were emphatically investigated,and the results provide theoretical basis and reference for the selection of experience parameter and improvement of oil spill models.Considering the environmental dynamic factors of oil spill,the flow laws of the instantaneous oil film area and thickness were studied at four special tides and winds,and oil slick's beaching time under different winds was analyzed.Meanwhile,the loss amount of evaporation and emulsification in the weathering process were studied by changing oil density,winds and sea temperature.Linking with possible conditions,the fate and behavior of spilled oil were studied from three conditions,including spilled oil,scale and style of leakage.The results show that currents and winds determine the oil-spill track and sweeping range,and oil spill accidents will cause different pollution area when it happened at different time.The winds could accelerate oil slick's movement,which has a decisive effect on it.Oil properties affect the oil spill area and the residence time in water.Evaporation amount will increase as the oil density becomes larger,while emulsification amount is in adverse.As for the winds and sea temperature,there is a positive correlation with evaporation and an optimal temperature and wind value for the amount of emulsion within a certain range.The first hour after the oil-spill occurred is the vital time for oil spill treatment,it can effectively prevent the oil spill area,which reduces pollution area of the sea.As for the complex style of leakage,the pollution areas caused by moving and continuous oil spill sources are larger than those of fixing and instantaneous oil spill sources.As a result,in the actual oil spill accidents,we should stop it when it is moving so as to avoid much larger pollution areas.The model-forecasting system,which was used to forecast the flowing process and area,had been applied into the “11.22” oil spill accident in Huangdao.And emergency plans had been compared from aspects both of the reaction time and intervening measures.The results show that sweeping range of adopting intervening measures at two and a half days later is reduced by 63% than taking no treatments.