A numerical model of storm surge in the Bohai and Yellow Seas of China was established based on the Delft3D model.Ninety-three storm events affecting this region from 1979 to 2020,including typhoons,cold waves,and extratropical cyclones,were selected.Storm surge and total water level were simulated.Using the Poisson-Pearson compound extreme distribution theory,extreme water levels for different return periods in the Bohai and Yellow Seas were estimated.Through numerical experiments,the nonlinear interaction between astronomical tides and storm surges on extreme water levels was quantitatively analyzed.Results show that the largest storm surges occur in Laizhou Bay and Bohai Bay in the Bohai Sea,as well as in Jianghua Bay and the western part of the West Korean Bay in the Yellow Sea.In these areas,the hundred-year storm surge can reach up to 4 m.Nonlinear interaction between astronomical tides and storm surges is more significant in estuaries and bayhead areas with large tidal ranges and shallow water depths.Compared with results from coupled models,nonlinear effects tend to underestimate extreme water levels.Linear superposition of astronomical tides and storm surges can significantly overestimate extreme water levels,with an overestimation magnitude of 0.5 to 0.8 m.Considering extreme water levels for return periods is crucial for coastal disaster prevention engineering.It greatly affects the safety and construction cost of coastal structures.Therefore,the nonlinear interaction between astronomical tides and storm surges on return period water levels should be taken seriously.
storm surgereturn periodstatistical analysisastronomical tideextreme water level
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