Climate change and urbanization will further exacerbate tropical cyclones (TCs) causing severer flooding especially in coastal urbanized areas. In this study, the compound effects of climate change and urbanization on organized TC and its flood risk across the Guangdong-Hong Kong-Macau Greater Bay Area (GBA) were explored and future projections of 10 models in different Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs) in Coupled Model Intercomparison Project 6 (CMIP6). The typical TC named Ewiniar that caused tremendous rainfall and flooding over GBA is taken as a case. We found that future TC will be exacerbated with rainfall band shifting inland and covering larger areas compared to the current scenario due to climate change and urbanization, and rainfall amount in the central rainfall band increases by 24% and 28% under SSP2-RCP4.5 and SSP5-RCP8.5, respectively. Due to the land-atmosphere interactions, future actual direct runoff increased by 7.91%–15.53% during the TC Ewiniar under SSP2-RCP4.5 and SSP5-RCP8.5, leading to further expansion of the area marked with the highest flood risk (24% and 39%, respectively). Our study highlights the adverse compound effect of climate change and urbanization on TC and flood risk, helping to develop TC-related disaster prevention and mitigation policies.

气候变化和城市化将进一步加剧热带气旋（TC），造成更严重的洪水，特别是在沿海城市化地区。本研究探讨了气候变化和城市化对粤港澳大湾区 (GBA) 有组织 TC 及其洪水风险的复合影响，并对不同共享社会经济路径 (SSP) 和耦合模型比对项目 6 (CMIP6) 中的代表性浓度路径 (RCP)。以造成大湾区大雨洪涝的典型 TC Ewiniar 为例。我们发现，由于气候变化和城市化，与当前情景相比，未来的 TC 将随着降雨带向内陆移动并覆盖更大的区域而加剧，在 SSP2-RCP4.5 和 SSP5-RCP8.5 下，中央降雨带的降雨量分别增加了 24% 和 28%。由于陆气相互作用，在 SSP2-RCP4.5 和 SSP5-RCP8.5 期间，TC Ewiniar 期间未来实际直接径流增加了 7.91%~15.53%，导致洪水风险最高的区域进一步扩大（分别为 24% 和 39%）。我们的研究强调了气候变化和城市化对 TC 和洪水风险的不利复合影响，有助于制定与 TC 相关的防灾减灾政策。分别）。我们的研究强调了气候变化和城市化对 TC 和洪水风险的不利复合影响，有助于制定与 TC 相关的防灾减灾政策。分别）。我们的研究强调了气候变化和城市化对 TC 和洪水风险的不利复合影响，有助于制定与 TC 相关的防灾减灾政策。