Compound flooding, characterized by the co‐occurrence of multiple flood mechanisms, is a major threat to coastlines across the globe. Tropical cyclones (TCs) are responsible for many compound floods due to their storm surge and intense rainfall. Previous efforts to quantify compound flood hazard have typically adopted statistical approaches that may be unable to fully capture spatio‐temporal dynamics between rainfall‐runoff and storm surge, which ultimately impact total water levels. In contrast, we pose a physics‐driven approach that utilizes a large set of realistic TC events and a simplified physics‐based rainfall model and simulates each event within a hydrodynamic model framework. We apply our approach to investigate TC flooding in the Cape Fear River, NC. We find TC approach angle, forward speed, and intensity are relevant for compound flood potential, but rainfall rate and time lag between the centroid of rainfall and peak storm tide are the strongest predictors of compounding magnitude. Neglecting rainfall underestimates 100‐year flood depths across 28% of the floodplain, and taking the maximum of each hazard modeled separately still underestimates 16% of the floodplain. We find the main stem of the river is surge‐dominated, upstream portions of small streams and pluvial areas are rainfall dominated, but midstream portions of streams are compounding zones, and areas close to the coastline are surge dominated for lower return periods but compounding zones for high return periods (100 years). Our method links joint rainfall‐surge occurrence to actual flood impacts and demonstrates how compound flooding is distributed across coastal catchments.

中文翻译：

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热带气旋复合洪水灾害评估：从调查驱动因素到量化极端水位

以多种洪水机制共同出现为特征的复合洪水是对全球海岸线的主要威胁。由于风暴潮和强降雨，热带气旋（TC）导致了许多复合洪水。先前对复合洪水危害进行量化的努力通常采用统计方法，这些方法可能无法完全捕获降雨径流和风暴潮之间的时空动态，从而最终影响总水位。相比之下，我们提出了一种物理驱动的方法，该方法利用大量的现实TC事件和简化的基于物理的降雨模型，并在流体动力学模型框架内模拟每个事件。我们运用我们的方法来调查北卡罗来纳州Cape Fear River的TC洪水。我们发现TC接近角，前进速度，强度和强度与复合洪水的潜力有关，但降雨率和降雨重心与峰值风暴潮之间的时滞是复合强度的最强预测因子。忽略降雨低估了洪泛区28％的100年洪水深度，而单独建模的每种危害的最大值仍低估了洪泛区的16％。我们发现河流的主要干流以涌浪为主，小溪和河流上游地区是降雨为主，而河流的中游部分为复混带，靠近海岸线的地区在较低的回水期以浪涌为主，但复混带高回报期（100年）。