Study On The Hurricane Storm Surge Disaster Assessment And Numerical Prediction Technique

In coastal areas of China, storm surge is the most serious marine disasters, whichcauses significant human life and property losses every year. So, scientific stormsurge disaster assessment and studies on accurate and fast storm surge predictiontechnique are quite necessary. This study focuses on the coastal area of Tianjin andnorth of Fujian province, where storm surge disaster is liable to occur.A storm surge simulation system was developed for Tianjin coast and foursevere hurricane storm surges in Tianjin history were simulated with this simulationsystem. The peak storm surge result of the simulation agreed well with that of theobservation. Based on the established strom surge simulation system, the storm surgedisaster risk was assessed when the hurricane moved along4designed paths, with anintensity of50year return period, and the mechanism of the strom surge formationwas analyzed. Finally, the easiest hurricane path type to cause storm surge disaster inTianjin was found. This study also shows that the effect of wind forcing and airpressure forcing on the storm surge is not linear, and the nonlinear interaction betweenthem tends to weaken the storm surge.A storm surge-wave coupled model based on ROMS (Regional Ocean ModelingSystem) ocean model and SWAN (Simulating Waves Nearshore) wave model wasestablished for the north of Fujian coast. Based on the coupled model, the influence ofwaves on the storm surge through wave-induced surface stress, bottom stress andradiation stress was studied in the process of hurricane "saomai". It was demonstratedthat:(1) The storm surge set-up on the right side of the hurricane path and theset-down on the left side of the hurricane path were both strengthened;(2) The bottomroughness was enhanced by the wave effect, causing the current to be decreased, andthen the storm surge was influenced;(3) The shoreward radiation stress can causeset-up along the coast, and the divergence of the radiation stress can cause set-down.Generally, the wave influences on the strom surge mostly through the surface stress,and then the bottom stress, and the last is the radiation stress. Based on the Model Coupling Toolkit (MCT), an unstructured stormsurge-waves-tide coupled model was developed. The developed coupled model hashigh resolution in the coast area and can be run efficiently. By comparing with theexisting coupled model, the newly developed one can increase the simulationefficiency by26.4percent, when the computational grid and coupling processes of thetwo coupled model were the same.This study is valuable to the study of hurricane storm surge disaster assessmentand the development of the operational storm surge prediction technique.