Numerical Simulation And Characteristic Analysis Of Storm Surge In Beibu Gulf

Storm surge is one of the most serious ocean disasters in the world,and it will cause lots of casualties and economic losses in coastal areas.China has a very long coastline,which is affected by the tropical cyclone in every summer and autumn,leading to serious storm surge in coastal areas.Especially in the Beibu Gulf coast of Guangxi,the storm set-up is usually higher.Therefore,the numerical simulation and characteristics analysis of storm surge in Beibu Gulf is of great importance to understand the mechanism of storm surge and do a good job in the work of disaster prevention and reduction.A coupled model of astronomical tide and storm surge for Beibu Gulf was established based on Delft3D model and Holland typhoon model.No.1409 and No.1415 typhoon storm surge were simulated based on this model,on the basis of verifying the accuracy of the model,a coupled model of wave,astronomical tide and storm surge was established.The results of the model was compared with the results of the coupled model of astronomical tide and storm surge,and the influence of wave on storm surge was analyzed.The result shows that the effect of wave on storm surge is more obvious in shallow coastal area,and there is less affected in deep water area south of Weizhou Island.The Monte Carlo method was used to generate 55 typhoons randomly according to the historical typhoon data of' 67a in the Beibu Gulf,the storm surge caused by the simulated typhoons were calculated by the coupling model,then the relationship between storm surge and typhoon parameters in key areas was studied.The result shows that the disaster of Tieshan Bay is mainly reflected in the intensity of the storm surge,and the disaster in Weizhou Island is mainly reflected in the frequency of storm surge.At the same time,one can estimate the scope of maximum set-up of Tieshan Bay according to the typhoon parameters,and one can judge the stage of the storm surge by the location of the typhoon.The temporal and spatial distribution characteristics of storm surge in the Beibu Gulf coast of Guangxi was studied.The result shows that the closer the location to the coast,the higher the maximum set-up is.Meanwhile,the storm surge in the Beibu Gulf has a lag effect on the typhoon,because the coast of Guangxi is located on the upper side of the typhoon entering the Beibu Gulf and the rotation direction of the typhoon in northern hemisphere is counterclockwise.Four sets of typhoon models were established based on the simulated typhoon No.36,and the effects of the typhoon path,the minimum center pressure,the maximum wind speed radius and the typhoon moving velocity on storm surge were studied respectively.The result shows that the farther the typhoon away from the coast of Guangxi,the smaller the maximum set-up.And the sensitivity of different locations to the typhoon path is different,the sensitivity inside the harbor is stronger.The lower the minimum center pressure of the typhoon,the greater the maximum set-up,and the center of the typhoon is more sensitive to the minimum center pressure.The larger the maximum wind speed is,the greater the maximum set-up is,and the greater scope of the storm surge.Generally,the larger the typhoon moving speed,the smaller the maximum set-up,but when the harbor scale is small,the typhoon moving speed has little influence on the maximum set-up.