Estimation of spatial extreme sea levels in Xiamen seas by the quadrature JPM-OS method

Continuing to enhance the understanding of occurrence probabilities of spatial extreme sea levels is a fundamental requirement of coastal hazard mitigation and prevention. To estimate spatial extreme sea levels in Xiamen seas, a hydrodynamic model capable of simulating storm surge was utilized. The applicability of this modeling approach to Xiamen seas was verified in view of a series of validations. A typhoon probabilistic model was emerged to generate synthetic typhoons governing the extreme sea levels. On the basis of the typical track shapes, a complete synthetic typhoon history was developed, while the astronomical tide was taken into account based on the Monte Carlo method. Simulation investigations driven by generated typhoons and corresponding astronomic tides were then conducted. Through simulation, 100 year and 200 year sea levels at Xiamen station were predicted to be 7.80 m and 7.93 m (Xiamen datum), respectively. Comparisons with the results issued by the Xiamen municipal bureau of water resources indicated that the quadrature JPM-OS approach can be applied to predict extreme sea levels during typhoons in Xiamen seas. Furthermore, 100 year and 200 year sea levels in Xiamen seas were determined. The results of this study also confirmed the existence of apparent spatial variation of extreme sea levels, which is likely to be related to the concavity of coastlines as well as islands and the topography. Estimating the spatial extreme sea levels provide clearer insight into different levels of flooding hazards in the study area, which is of great benefit to the design of coastal hazard mitigation and prevention plans.