Numerical Analysis Of Storm Surge In The Region Of The Changjiang Estuary And The Hangzhou Bay

Storm surge is a common natural phenomenon that the sea level rises abnormallydue to intensive atmospheric perturbation such as strong wind and sudden decline ofatmospheric pressure. The region of the Changjiang estuary and the Hangzhou Bay isoften attacked by the storm surges because of their unique location and natureenvironment, especially the ones caused by typhoon, leading loss of lives and propertydamage. Therefore, the study of the storm surge in this region using numerical model ishelpful for the prediction and prevention of this natural disaster.In this paper, FVCOM (finite volume coastal ocean model) is used to establish a3Dhydrodynamic numerical model whose computation domain covers the East China Sea.Firstly, the tide in this region is simulated and the results are compared with theobservation data during the September,2002, which demonstrates that the simulationresults agree with the observation data well. Then, three typhoons are adopted，whichare TC8114, TC9711, TC0012. The storm surges caused by them are simulated and theresults prove that the numerical model can be used for the prediction and analysis of thestorm surges in the region of the Changjiang estuary and the Hangzhou Bay.Finally, a series of sensitivity experiments are carried out in this paper in order tostudy the impact of five different factors of typhoon, the land point, the approachingspeed, the direction, the maximum wind speed radius, the maximum wind speed and thecentral pressure on the storm surges in this region. The conclusion is drawn that, as to thenortheasterly approaching typhoons, the ones landing near the Zhoushan make largersurges in the Hangzhou Bay. The ones landing near the Chongming cause larger surges inthe Changjiang estuary but set down the water level in the Hangzhou Bay. The oneslanding in the middle and southern part of Zhejiang Province, lead to smaller surges inthe Changjiang estuary the land point moving southward, but larger surges in theHangzhou Bay on the contrary. The typhoons with slow approaching speed yield largersurges than fast due to the time required to redistribute water mass, the surges in the Hangzhou Bay are more sensitive to the approaching speed compared with theChangjiang estuary. The typhoons transiting up the Hangzhou bay axis from east to westmake the largest surge within the bay. However, the condition outside the bay is different,the typhoons from southwest to northeast yield the highest surge. As to the Changjiangestuary, the typhoons from southeast to northwest and from south to north are responsiblefor larger surges. The maximum surges increase remarkably with maximum wind speedradius being larger, in the same time the trend becomes mild. The effects of maximumwind speed and central pressure are also investigated. The surges are more sensitive tothe change of the maximum wind speed than the central pressure. The maximum surge isproportional to the square of the maximum wind speed and increases by0.02to0.05mwith every10hPa decline in central pressure.