Numerical Simulation Of Storm Surge In The Nearshore Coastal Closed Bay Of Wukan

Guangdong Province is located on the west coast of the Pacific Ocean and borders the South China Sea,which is one of the main areas where typhoons landed in China.Guangdong province is hit by typhoons in summer and autumn every year.According to statistics,there were a total of 506 typhoons affecting Guangdong province from 1949 to 2007,with an average of 8.7 typhoons affecting Guangdong province every year.Among them,201 typhoons landed,accounting for 39%of the affected typhoons,with an annual average of 3.47.A storm surge is often caused by the violent rise and fall of the tide when a typhoon makes landfall.Because of its ferocity and destructive power.In a very short period of time,the breach of the seawall will result in the intrusion of seawater into towns and villages,causing the collapse of houses,casualties of human and livestock,flooding of farmland,pollution of fresh water resources,destruction of mariculture industry,and causing huge losses to people's lives and property as well as industry and agriculture.Therefore,this paper mainly focuses on Wukan,Lufeng,Shanwei City,Guangdong Province as the main research area.The FVCOM two-dimensional tidal current model is used to simulate the nearshore current,the FVCOM-SWAVE ocean wave model is used to simulate the wave field,and the WRF mesoscale atmospheric model is used to simulate the super typhoon No.201319 Usagi.A coupling model of astronomical tide-storm surge-ocean wave is established.The main results are as follows:1.Based on WRF simulation to verify Typhoon Maria and verify the reliability of WRF model.The sensitivity analysis of Typhoon Usagi which is based on the microphysical parameters and the cumulus convection parameterization scheme in the WRF mode was carried out.And the optimized parameters were determined to obtain a high-precision wind field by comparing and analyzing the measured wind speed and typhoon moving track.The results show that the WSM5_Tiedtke scheme is more suitable for the numerical simulation of the wind field during the typhoon Usagi.2.The tidal current in Wukan which is based on the FVCOM two-dimensional tidal current model was verified.Based on the FVCOM-SWAVE model,the different wind drag coefficients,the bottom friction parameter and the wave breaking coefficient was considered on the typhoon wave propagation.And then verifying the typhoon Usagi during wave propagation procsess.The results show that the Wu2.5 scheme and the MADSEN scheme are the best,and the wave breaking coefficient and bottom friction coefficient have little effect.The highprecision wind field obtained from the WRF model was loaded into the wind-wave-current coupling model to verify the storm surge of Typhoon Usagi.3.Based on the tide-storm-surge-wave coupling model,taking wind intensity as a consideration factor,the influence of wind speeds and sea surface pressures on Wukan Bay is compared and analyzed.The results show that the most important factor of storm intensity on the storm surge level inside and outside Wukan Bay is the impact on the changes in the flow field in Wukan Bay.If the storm intensity has little effect on the flow field inside and outside Wukan Bay,the increase of the storm intensity will lead to the increase of the storm surge level.If the intensity of the storm changes the flow field inside and outside Wukan Bay,the impact of the intensity of the storm on the storm surge level will be reduced.