Tropical cyclone (TC) induced compound floods involve dynamic interactions among astronomical tides, storm surges, precipitation, and associated river pulses. This study employs a one-way coupled WRF, Delft3D, and HEC-RAS model to investigate the impacts of oceanic, pluvial, and fluvial processes on compound flood dynamics during Typhoon Hato (2017) in the Pearl River Estuary (PRE), South China. Total water levels driven by different combinations of flood drivers are modeled and analyzed. Relative contributions of each type of flood driver are quantified and used to categorize flood zones. This study highlights the persistent impacts of storm surges and their nonlinear interactions with other flood drivers. They can modify both the timing and magnitude of maximum water levels, thereby distorting tidal signals and contributing to post-TC landfall water level peaks. Along coastal regions, water levels exhibit three successive peaks, predominantly driven by storm surge, rainfall, and the combined actions of both factors, respectively. In upstream regions and coastal areas sheltered from islands, a singular water level peak arises exclusively from rainfall-runoff processes. Moreover, nonlinear interactions between surge and rainfall-runoff have non-negligible impacts on the relative contribution of individual flood drivers, which underscores the necessity of considering both rainfall and storm surge in modeling compound flood water levels. During the flooding period, peak storm surge and the following peak rainfall resulted in a time-varying distribution of flood zones. Alternating feedback between compounded and ocean-dominant areas manifests in the midsections of the upper PRE. Maximum flooding depth, extent, and duration are mainly influenced by rainfall. Storm surges play a secondary role, causing intense but short-lived flooding in coastal regions. These findings aid in understanding the generation mechanism of compound floods and provide references for hazard mitigation strategies.

中文翻译：

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描述珠江口的交互式复合洪水驱动因素：以台风天鸽为例（2017 年）


热带气旋 （TC） 诱发的复合洪水涉及天文潮汐、风暴潮、降水和相关河流脉搏之间的动态相互作用。本研究采用单向耦合 WRF、Delft3D 和 HEC-RAS 模型来研究华南地区台风天鸽 （PRE） 期间海洋、雨流和河流过程对复合洪水动力学的影响（2017 年）。对由不同洪水驱动因素组合驱动的总水位进行建模和分析。对每种类型的洪水驱动因素的相对贡献进行量化，并用于对洪水区进行分类。本研究强调了风暴潮的持续影响及其与其他洪水驱动因素的非线性相互作用。它们可以改变最大水位的时间和大小，从而扭曲潮汐信号并导致 TC 登陆后水位峰值。沿着沿海地区，水位呈现出三个连续的峰值，主要由风暴潮、降雨和这两个因素的综合作用驱动。在远离岛屿的上游地区和沿海地区，单一的水位峰值完全由降雨径流过程产生。此外，浪涌和降雨径流之间的非线互作用对单个洪水驱动因素的相对贡献具有不可忽视的影响，这强调了在模拟复合洪水水位时同时考虑降雨和风暴潮的必要性。在洪水期间，风暴潮峰值和随后的降雨高峰导致洪水区的分布随时间变化。复合区和海洋主导区之间的交替反馈表现在上 PRE 的中段。最大洪水深度、范围和持续时间主要受降雨影响。 风暴潮起着次要作用，在沿海地区造成强烈但短暂的洪水。研究结果有助于理解复合洪水的产生机制，为减灾策略提供参考。