Numerical Simulation and Analysis of Joint Multi-Line to Defend Storm Surges Due to a Super Typhoon

This paper aims to the inundated conditions which probably occur in the macro-tidal estuary where the floodplains are lower than the high tidal level. A high Precision two-dimensional numerical model is developed to simulate the inundated degree introduced by storm surges taking the Qiantangjiang estuary coastal area as an example. Except for the sea area, both sides of the floodplains are included in the calculation scope. Meanwhile, the secondary dikes owing to the reclamation projects and some roads which have the effect on tide resistance are considered. In this article, the front dikes damaged scale is determined by Interior Wave Model Experiment^[3], Safety Assessment of the Front Dikes’ Ultimate Defense Capability^[11]. Using the model, this paper simulated inundated conditions under the typical super typhoon which takes Typhoon No.5612, the most intense typhoon landed in china since 1949, as the controlling conditions. According to the calculated results, this paper analyzed the effects of joint multi-line defense (the secondary dikes and roads) behind the front dikes and obtained action sphere and role of each defense. These results can be applied to direct the defense of storm surges over designed standard occurring in the macro-tidal estuary.