Abstract: Catastrophic storm surge inundation resulted from 9417 typhoon was simulated with an numerical model of ultrahigh resolution for storm surge inundation which is based on unstructured grid and can calculate the overflow discharge. The results agree well with the observations. Three paths of south, mid and north with that of 9417 typhoon as the south-path and 30 km interval from one another were designed for a series of numerical simulations with the strength of 9417 typhoon, which show that the coastal dike in Wenzhou has enhanced the menace of storm surge and inundation on the city, and the inundation depth caused by the south path and the inundation area caused by the mid path is the most. The reason is that the obstruction and diffluence of the dike on the propagation of the storm surge from open sea at the costal waters and Oujiang river estuary multiply the water transfer into the north side of Oujiang river estuary, the north end of the estuary and its mid and upper reaches.

Key words: Wenzhou coastal dike, high-resolution numerical model, overflow, typhoon storm surge inundation