The passage of a tropical storm, as the main driver of storm surge and high waves in many coastal regions, can also generate heavy rainfall and cause river overflow. The resulting combination of riverine, pluvial, and coastal flood hazard can result in catastrophic losses particularly in densely populated coastal environments. In this study, we characterize compound flooding caused by Tropical Storm Matthew and assess the significance and associated uncertainties of multiple contributing factors over a data‐scarce coastal region. A hydrological model combined with a simplified two‐dimensional hydrodynamic model are set up and validated to investigate the compounding effects of storm tide, wave runup, rainfall, and river overflow at the southern coast of Saint Lucia in the Caribbean Sea. Pléiades‐1 and Sentinel‐1 satellite imageries are used to determine the flood‐impacted areas. The analyses are performed based on deterministic and probabilistic approaches and the effects of uncertain boundary conditions and model parameters are investigated. Results show that the individual analysis of flood hazards, in isolation, can lead to substantial underestimation of flood risks. Heavy rainfall and wave runup are the most significant contributors to compound flooding in Saint Lucia. In addition, the interactions between seawater and streamflow can exacerbate riverine flood hazards particularly upstream of the river mouth. Communities in western Vieux Fort, and the Hewanorra International Airport, have high exposure to compound flooding, which is projected to intensify under climate change.

中文翻译：

---

数据稀缺的沿海环境中热带风暴马修造成的复合洪水的概率数值模拟

作为许多沿海地区风暴潮和大浪的主要驱动力，热带风暴的通过也可能产生大量降雨并引起河流溢流。造成的河流，河流和沿海洪水灾害的综合后果可能导致灾难性损失，尤其是在人口稠密的沿海环境中。在这项研究中，我们描述了由热带风暴马修（Matthew）引起的复合洪水的特征，并评估了数据稀缺的沿海地区多个影响因素的重要性和相关的不确定性。建立了水文模型并结合了简化的二维水动力模型，以研究加勒比海圣卢西亚南部海岸的风暴潮，波浪径流，降雨和河流溢流的复合影响。Pléiades-1和Sentinel-1卫星图像用于确定受洪水影响的区域。分析基于确定性和概率方法进行，并研究了不确定边界条件和模型参数的影响。结果表明，单独进行洪水危害分析可能导致严重低估洪水风险。暴雨和海浪上升是圣卢西亚复合洪水的最主要因素。另外，海水和水流之间的相互作用会加剧河道洪水的危害，特别是在河口上游。西部老堡和希瓦诺拉国际机场的社区极易遭受复合洪水的袭击，预计在气候变化下加剧。分析基于确定性和概率方法进行，并研究了不确定边界条件和模型参数的影响。结果表明，单独进行洪水危害分析可能导致严重低估洪水风险。暴雨和海浪上升是圣卢西亚复合洪水的最主要因素。另外，海水和水流之间的相互作用会加剧河道洪水的危害，特别是在河口上游。西部老堡和希瓦诺拉国际机场的社区极易遭受复合洪水的袭击，预计在气候变化下加剧。分析基于确定性和概率方法进行，并研究了不确定边界条件和模型参数的影响。结果表明，单独进行洪水危害分析可能导致严重低估洪水风险。暴雨和海浪上升是圣卢西亚复合洪水的最主要因素。另外，海水和水流之间的相互作用会加剧河道洪水的危害，特别是在河口上游。西部老堡和希瓦诺拉国际机场的社区极易遭受复合洪水的袭击，预计在气候变化下加剧。