The low-lying Pearl River Delta in South China is subject to severe flood threats due to watershed floods, sea level rise, and storm surges. It is still unknown to what extent and how far inland storm surges and sea level rise impact the extreme flood stages. This study investigated the coupling effect of flood discharge and storm surge on the extreme flood stages in the Pearl River Delta by using on site observations and simulations generated by the Hydrologic Engineering Center-River Analysis System model. The results show that flood discharges dominated the flood stages in the middle and upper Pearl River Delta, while the storm surges had maximum impact near the river mouth. The storm surges and flood stages showed a significant increase after 2002 in the Hengmen waterway. The design flood stages for the post-2002 period were 0.23–0.89 m higher than the pre-2002 ones at Hengmen at the six return periods from 5 to 200 years examined in this study. Their difference declined toward the upper waterway and reduced to zero about 23 km away from the Hengmen outlet. The coincidence of extreme flood discharges and storm surges further escalates the extreme flood stages in the lower 30 km of estuarine waterways. Our results quantify the severe threats due to sea level rise and intensified storm surges in the lower Pearl River Delta, and are significant for urban planning and designing and managing flood control facilities in the Pearl River Delta and in other coastal fluvial deltas.

由于流域洪水、海平面上升和风暴潮，华南地势低洼的珠江三角洲面临严重的洪水威胁。目前尚不清楚内陆风暴潮和海平面上升对极端洪水阶段的影响程度和程度。本研究利用水文工程中心-河流分析系统模型生成的现场观测和模拟，研究了洪水和风暴潮对珠江三角洲极端洪水阶段的耦合效应。结果表明，珠江三角洲中上游洪水阶段以泄洪为主，而风暴潮在河口附近影响最大。2002年以后，横门水道的风暴潮和洪水阶段显着增加。2002 年后的设计洪水位为 0.23-0。在本研究中考察的 5 到 200 年的六个重现期中，横门比 2002 年之前的高 89 m。它们的差异向上游航道减小，并在距横门出口约 23 公里处减小到零。极端洪水排放和风暴潮的同时发生进一步加剧了河口水道下游 30 公里的极端洪水阶段。我们的研究结果量化了珠江三角洲下游海平面上升和风暴潮加剧造成的严重威胁，对珠江三角洲和其他沿海河流三角洲的城市规划、设计和管理防洪设施具有重要意义。它们的差异向上游航道减小，并在距横门出口约 23 公里处减小到零。极端洪水排放和风暴潮的同时发生进一步加剧了河口水道下游 30 公里的极端洪水阶段。我们的研究结果量化了珠江三角洲下游海平面上升和风暴潮加剧造成的严重威胁，对于珠江三角洲和其他沿海河流三角洲的城市规划、设计和管理防洪设施具有重要意义。它们的差异向上游航道减小，并在距横门出口约 23 公里处减小到零。极端洪水排放和风暴潮的同时发生进一步加剧了河口水道下游 30 公里的极端洪水阶段。我们的研究结果量化了珠江三角洲下游海平面上升和风暴潮加剧造成的严重威胁，对于珠江三角洲和其他沿海河流三角洲的城市规划、设计和管理防洪设施具有重要意义。