Numerical Simulation And Statistical Analysis Of Typhoon Storm Surge Along Jiangsu Province

Storm surge means the phenomenon of sea level increasing caused by strong atmospheric disturbances,such as typhoon,extra-tropical cyclone and tropical cyclone.When it approaches astronomical high tide,water level will increase rapidly and the land may be flooded.The coastline of Jiangsu province is 954km,accounting for about 6%of the total length of the national coastline.The storm surge caused by the typhoon poses a great threat to the east and south coasts of Jiangsu province.Among the disaster factors of storm surge,the hazard of increasing water by storm surge ranks first.Therefore,this paper explores the impact of storm surge on the coastal areas of Jiangsu,using a combination of numerical simulating and statistical analyzing.In order to provide data support for the analysis of the extreme value of typhoon storm surge in Jiangsu coastal areas,this paper uses the numerical model to report the extreme value of the typhoon storm surge process.The ADCIRC model was used in the post-report.The topographic water depth used in the model was spliced from the global land and ocean elevation data ETOPO1 and the measured water depth data.The computational grid adopts the unstructured triangular grid which is encrypted in the coastal boundary of Jiangsu province.In this paper,wind field and pressure field are simulated by Fujita typhoon model.The necessary data are from typhoon almanac of China.The tidal boundary conditions consist of four tidal waves,and the harmonic constants come from the TPXO8-atlas model.Through the storm surge simulation of the historical typhoon case and the comparison with the results of the measured data,the comparison results show that the mean absolute error(MAE)of maximal surge is 7.9cm,the MAE of peak-value time 1h,which meet the requirements of simulating.So the ADCIRC storm surge model can be used in the study of storm surge in coastal areas of Jiangsu.The numerical model was used to calculate the process of 42 typhoons that affected the coastal areas of Jiangsu province during the 40 years from 1977 to 2016.In the process of statistical analysis,six kinds of extremely common theoretical extreme value distributions,including Gumbel distribution,Weibull distribution,lognormal distribution and so on,were compared for goodness of fit.The K-S test,root-mean-square error method,AIC method and other methods were used to evaluate the fitting degree of sample empirical distribution function and each distribution function.Comparing the comprehensive statistics,the best fit is the generalized extreme value distribution,so the generalized extreme value distribution and the Poisson distribution are chosen to form a composite distribution.After the typhoons from 1977 to 2016 are simulated using the verified ADCIRC model,the 100-year return storm surge elevations are calculated making use of the Poisson-Gev distribution.The corresponding calculated results are 390.0cm and 271.4cm in Lvsi and Yangkou,which will be adopted to prevent storm surge disaster in the near shore area of Jiangsu Province.