Author(s): Cheng Chen; Tingyu Wang; Xin Deng
Linked Author(s):
Keywords: Seawall breach; Typhoon waves; Astronomical tides; Numerical simulation; Flood inundation
Abstract: Super Typhoon Maria (1808) struck Fujian Province, China, coinciding with a high astronomical tide. This event led to the breach of the seawall in Yacheng Town, Xiapu County, Ningde City, and subsequent flooding of the town due to the seawater backflow. To comprehensively examine the patterns of seawall breaches and the breach process under the combined influence of typhoon waves and astronomical tides, this research adopted a methodology involving the superimposition of tidal levels and typhoon waves. This approach simulated the progressive development and flooding scenario of the breached seawall under various conditions. The study's objective is to establish a theoretical foundation and offer technical insights for disaster prevention and mitigation in coastal engineering. This study conducted simulations to assess the combined impact of astronomical tides and typhoon waves on seawall failures, specifically overtopping and piping failures. The obtained results were compared with scenarios where piping failure was solely due to astronomical tides. It was observed that the outcomes of the first two cases exhibited similarities, with a peak discharge flow of around 230 m3/s and a breach width of 26 m. In contrast, the discharge flow resulting from astronomical tides alone was significantly lower at 22 m3/s, accompanied by a narrower breach width of 8 m. Additionally, the article independently modeled the progression of flooding in the aforementioned scenarios following a seawall breach. Taking the flooding due to overtopping as an illustration, the maximum inundation area was reached at approximately 120 minutes, with a maximum depth of 3.10 meters and an average depth of 1.23 meters. Subsequently, as the astronomical tide receded, floodwater gradually drained through the breach.
Year: 2023