Numerical Modeling Of Storm Tide In Guangxi Beibu Gulf

Storm surge is the major marine disasters in Guangxi. The unique geographical features of Guangxi coastal area which is located in the top of Beibu Gulf makes Guangxi storm surge different to other coastal area in own country. The numerical simulation of storm surge is helpful to understand the storm surge characteristic and dynamic mechanism in this region.In this paper, we established a reasonable ideal typhoon wind field by inversing the observed wind data of No.1213 typhoon “Kai-tak”. We also established a FVCOM ocean dynamic model tested by the tide data. Basing on this two models, A storm-tide coupling model was established, which was testing by the observed surge elevation and tide elevation data.The numerical simulation of typhoon “Kai-tak” typhoon storm surge shows that: North region is the major active area of typhoon “Kai-tak”, where the main storm surge happened. This typhoon can stir the whole water in Beibu Gulf, while the effect is more remarkable in the north of gulf and surface water. The variation of surge distribution and residual current field is correspond with wind structure of typhoon and it’s track.The simply correlation relationship between storm surge and storm moving speed in Beibu Gulf did not exist. On the one hand, as the cyclone moving speed increases, the components of cyclone wind field in the direction of cyclone movement increase which can be beneficial to storm surge; on the other hand, the cyclone moving speed increases which can shorten the time of its impact on Beibu Gulf, the shorter wind duration were also unfavorable to enhance the storm surge; at the same time, as the storm moving speed change, the fluctuation cycle of storm surge process changes, the interaction between storm surge water level fluctuation and reversion wave of coast also changes, actual tidal level will also change. Strengthening of typhoon intensity will enhance the amplitude of storm surge, but not affect the frequency of storm surge.The different surges in the sites also reflect the impact of terrain in Beibu Gulf on storm surge, on the whole, it shows the trend that the surge of gulf is stronger and the surge in the open coast is weaker, the sea area is the minimum. At the same time, the closed narrow geographic features of Beibu Gulf also lead to the impact of resurgence wave of coast is more obvious, the storm surge curve of Beibu Gulf shows the characteristic that the residual vibration is longer and the disturbance of main vibration is more.