Simulation And Analysis On Coupling Typhoon Storm Surge With Wave In Zhoushan Fishery Harbor

Zhoushan fishery harbor is the national central fishery harbor whose nearby waters have abundant fishery resources,but storm surge and wave caused by typhoons seriously threaten its safety.It is of great significance for marine disaster prevention and mitigation to study the spatial and temporal distribution of typhoon storm surge and wave and their interaction in Zhoushan fishery harbor.Based on the Flow and Wave modules of Delft3D,the coupled model of typhoon storm surge and wave for Zhoushan fishery harbor was established on concentric circle grid.The simulated values of tidal level,current velocity and effective wave height were in good agreement with the measured data.Compared with the uncoupled model,the coupled model could simulate typhoon storm surge and wave better.The simulation accuracy of storm surge level could be increased by 26 cm,and that of maximum wave height could be increased by 8.63%.The storm surge and wave processes in Zhoushan fishery harbor during Typhoon 9711 were simulated.The results showed that the maximum storm surge of 1.283 m and tidal level of 3.151 m occurred at the 65th and 70th hour,respectively.The surge and tidal level increased from southeast to northwest.The surge in the south shore was greater than that in the north shore,and the tidal level changed little horizontally.The maximum storm current speed was 0.575 m/s at flood tide,and the increment of current speed caused by typhoon was 0.269 m/s at most.The speedup effect increased along the northwest.At ebb tide the maximum storm current speed was 0.228 m/s,and the reduction of current speed caused by typhoon could reach 0.189 m/s at most.The storm current speed was first decreased and then increased to the southeast,but the deceleration effect was just the opposite.At the 72nd hour during the typhoon,the wave height of fishery harbor reached maximum about 1.104 m which appeared in Area V.The wave height first decreased and then increased from Area I to V,and in the north shore was generally greater than that in the south shore.The numerical experiments of the interaction between storm surge and wave in the fishery harbor during Typhoon 9711 showed that the coupling effect could not be neglected in the simulation.At the 65th hour,wave setup was greatest in the fishery harbor,and its contribution rate to storm surge varied from 19.8%to 25.9%.At the 70th hour,the storm surge level was highest,and the water depth was deeper,so the contribution rate of wave to storm surge was less than 10%.The wave decreased current speed at flood tide.At ebb tide,the wave increased current speed in Area ? to ?,but decreased it in Area V.The effect of wave on current direction was generally not obvious.At 72nd hour,the storm surge had the most obvious effect on wave height,and storm surge level increased wave height with maximum increment about 0.258 m.The storm surge current increased wave height in Area ? to ?,and decreased it in Area ?to ?.The contribution rate of storm surge current to wave height increment was obviously less than that of storm surge level.