A Preliminary Study On The Water Level Fluctuations And Flow Field Of Bohai Sea Induced By Storm Surge

Storm surge is one of the most serious oceanic disasters in coastal zone in China.First, a comprehensive literature review is conducted and analyzed on the storm surgein Bohai Sea area. Then a numerical model of astronomical tide and storm surge areconstructed. The model is verified and calibrated with astronomical tide, and theresults are reasonable agree with the predicted values in tidal table. At last, the modelis applied to simulate the temperate zone storm surge in Oct. 2003 and typhoon stormsurge No.9711. Analyzed are the water level fluctuation and the spatial-temporalvariation of the flow field due to the surges.The influence of the evolution processes are modeled for extratropical stormsurge. Due to the long duration and strong intensity of the temperate zone cyclone, thearea with water level fluctuation is large. Under the effect of the surge, the sea wateris driven from Laizhou bay to Bohai bay, as a result, there is negative setup inLiaodong bay and setup in both Laizhou bay and Bohai bay. Meanwhile, due to thetemperate zone cyclone, the tidal flow of Bohai Sea varies greatly. The local reversingtidal current is changed to unidirectional flow, and the ratio of local rotary tidalcurrent ellipse's major and minor axis changes too.The numerical simulation is conducted for typhoon storm surge No.9711. Thearea with water level fluctuations and the influences on flow field are smaller thanthose of the extratropical storm surge. This may be due to the fast varied directions ofthe typhoon.The nonlinear interaction between astronomical tide and storm surge areanalyzed for the water level fluctuations of extratropical and typhoon storm surge.The water level fluctuations due to nonlinear interaction can not be neglected in theoffshore zone with shallow water and large tidal ranges. The water level fluctuationshave a period close to the astronomical tidal period. The problems remained and somerecommendations for the future research are summarized at last.