Numerical simulation and analysis on tidal inundation of northern plain in Qiantang River estuary under ultra-violent typhoon

In the light of the estuary area of the Qiantang River where the elevation of inland protection area is lower than the river water level,and taking the most strong landfall typhoon "5612" in the costal area of China since 1949 as the control condition,the numerical simulation and research on inundation condition of the northern plain of the Qiantang River estuary are conducted.In the simulation and research,we generalize the topography,and solely treat second-line embankments and the roads which have tide-against function;and determine the destroy degree of sea bank under the ultra-violent typhoon according to the analyzed limiting defense capability of the sea bank;finally,calculate and analyze the inundation condition of the northern plain by 2-D storm surge model which can cover both-side areas.The analysis result show that under the ultra-violent typhoon,the inundation area of the Qiantang River estuary can stretch forward with time increasing along the second-line embankments and roads,and these kinds of structures have satisfying tide-against role;under the present condition,when ultra-violent typhoon landfalls on the northern plain of the Qiantang River,the largest inundation depth will reach 2.87 m with an inundation area of 127.52 km2.