Improved Wind-field-based Simulation Of Storm Surge In Zhoushan Fishery Harbor

The Zhoushan Fishery Harbor serves the world famous Zhoushan Fishery Ground.There are large number of fishery boats in the harbor.From 1951 to 2018,about 110 storm surges affected the fishery harbor.And carrying out numerical simulation of storm surge level has great significance for disaster prevention and reduction of fishery harbor.This dissertation introduces a sea surface resistance term proportional to wind speed to correct the gradient wind equation,and according to the characteristics of typhoon profile,a new formula of pressure is proposed.Then substituting them into the modified gradient wind equation to derive the gradient wind speed formula and construct a new wind model.The pressure and wind velocity profiles of the cyclone Joan,Tracy and Betty are calculated according to Holland,Fujita-Takahashi and the model of this dissertation.The calculated results of pressure are compared with the measured data,and the skill scores are all up to 0.99.The skill scores for wind velocity in this dissertation model are 0.93?0.99,and the accuracy is significantly higher than other modes.Using Delft 3D to establish a nested mesh storm surge model in Zhoushan Fishery Harbor According to the data of China's offshore typhoon,the relationship between the maximum wind speed radius and the central pressure is obtained.The nested storm surge model combined with Holland or the mode of this dissertation simulates the storm surge level during Typhoon 9417,9711,0509 and 1211 which affecting Zhoushan,and the comparison between the simulated value and the measured value shows that this dissertation model has better storm surge simulation effect.According to the data of typhoon affecting Zhoushan,and five kinds of virtual roads were structured to simulate the storm surge level in the fishery harbor.The results show that the storm surge level caused by the typhoon landing on the south side is higher than that on the north side,and the highest storm surge level occurs on the SE-R-track.Under the three kinds of typhoon center moving speed on the SE-R-track,the slow typhoon acts on the fishery harbor for the longer period of time,and the storm tidal level is the highest The western end of the seawall on the harbor area's north shore cannot withstand the storm surge level of the 12 grade typhoon,the central part can withstand the storm surge level of 17 grade typhoon,and the typhoon resistance of the eastern end of the seawall is about 12?15 grade.The dissertation calculates the wind and flow force of the fishery boats in the harbor under 10 typhoon tracks,and the results show that the typhoon landing on the south side makes it easier for the fishery boat to anchor.The fishery boat is the most stressed on the S-R-track,and under 14 grade typhoon the force of the fishery boat close to the anchor grip force 25.28 kN,in this case,the parking area is 3.04 km2.In addition,when the typhoon grade is 15?17,the parking area in the harbor is 0.55 km2.Adding 8 paths in the SE and S directions,to calculate the storm surge level and the wind-flow force.As the two sides of Zhoushan Fishery Harbor pass through the sea,the wind velocity increases the trend of entering upswing on the SE-R' track,while it is at an angle of 13°with ESE direction fishery harbor,which is conducive to the water detention in the harbor area,therefore the probability of the overflow is the largest.The wind direction of S-0.5R-track is approach orthogonal with the trend of Fishery harbor,the wind-flow force of fishery boats are biggest,the risk of walking anchor in this case is highest.The dam is arranged on the west side of Xiaogan Island,and the probability of the overflow when the 17 grade typhoon acts is reduced by 3.3%,moreover the dam is arranged on the east side of Xiaogan Island,the mooring area under the action of the 14 grade typhoon is increased by 0.9 km2,in a word,both of them can improve the ability of fishery harbor defense.