Study On Berthing Capacity Evaluation Of Zhejiang Fishing Port Under The Influence Of Typhoon

China is one of the countries with the most serious marine disasters,among which typhoon wave disaster is the first.There are many fishing ports in Zhejiang Province,which are affected by storm surge disasters all year round and suffer heavy losses.Typhoon-induced waves pose a serious threat to offshore production activities,especially to the ability of fishing ports to avoid the typhoon.As an extreme weather phenomenon,typhoons are one of the most threatening natural disasters in coastal areas.The strong winds,huge waves and torrential rains it brings often cause serious economic losses and casualties in the areas it passes through.Especially in coastal areas where typhoons occur frequently,fishing ports have different capacities to withstand typhoons,and the safety of fishing vessels in the port to avoid typhoons is becoming increasingly serious,and the construction of fishing port capacity to avoid typhoons is given high priority.During the period 2009-2018,246 typhoons were generated in the Northwest Pacific Ocean and the South China Sea,of which 30,or 12.2%,affected Zhejiang Province,China,with direct economic losses of US$1,236 million.This illustrates the poor sheltering capacity of many fishing ports in China and the lack of security of fishing vessels at anchor during typhoons.When a typhoon crosses the harbour,typhoon waves severely damage port structures such as quays and breakwaters,while threatening the safety of ships.Fishing vessels often enter fishing ports or anchorages to take shelter from typhoons,thus achieving typhoon mitigation,which makes the ability to take shelter an important indicator of the reliability of fishing ports.Fishing ports in Zhejiang Province have problems such as inadequate sheltering capacity of fishing vessels and the high wind shelter requirements for fishing ports in typhoons pose certain difficulties to the safety management of fishing ports.Further,in the face of the frequent threat of extreme weather,it is crucial to assess the sheltering capacity of fishing ports,providing strong technical support for the safety management of fishery production.Offshore fishing ports are frequently hit by extreme weather conditions such as typhoons.An objective and reasonable assessment of the berthing capacity of fishing ports is crucial to the safety of offshore production.We combined the MIKE21 Spectral Wave model with the Holland wind model to reproduce the typhoon wave characteristics during typhoon transit,and further assessed the berthing capacity of the Zhejiang fishing ports under different recurrence periods and different path effects.The significant wave heights and water levels calculated by the model are in good agreement with the observations,and the d-trend model evaluation shows that our model performs well.Based on the significant wave height and stable mooring conditions for fishing vessels,the berthing capacity of the fishing port was more reasonably assessed.From the typhoons affecting Zhejiang,Typhoon In-Fa,Typhoon Lekima and Typhoon CHAN-HOM were identified as the representative typhoons.Based on the typhoon data,the typhoon data were translated to the center of a typical fishing port in Zhejiang,and three paths were formed with a spacing of 12 km,and then the typhoon recurrence periods were calculated by the p-III curve parameter estimation method to obtain the typhoon intensity of 50 a and 100 a.The significant wave height,anchor grip,typhoon path and different recurrence periods of typhoon on the berthing capacity of fishing ports were analyzed.Under the influence of landfalling typhoon,as the typhoon path moves northward,the effective sheltering area of the fishing port gradually decreases,and the sheltering capacity of the fishing port decreases.Under the influence of northward typhoons,the effective sheltering area of fishing ports gradually increases as the typhoon path moves eastward,and the sheltering capacity of fishing ports increases.The impact of different recurrence periods of typhoons on the wind sheltering capacity of fishing ports is also different.When the recurrence period decreases from 100 a to 50 a,the wind sheltering area of fishing ports increases and the wind sheltering capacity of fishing ports increases.This study can provide reference for disaster reduction and berthing management of offshore fishing ports.