极端降水事件空间集中度的增强会加剧城市暴雨内涝灾害的风险，严重影响居民的生活和安全。降水事件的空间集中度可能在气候变化和城市化共同作用下增强，然而针对典型城市区降水事件空间集中度的研究工作还处于发展阶段。本项目选择城市化快速发展的珠江三角洲作为研究区，试图回答：（1）不同气象背景下降水事件空间集中度的特征和影响因素；（2）不同气候变化和城市化发展情景下降水事件空间集中度的未来变化。本项目首先提出基于基尼系数的降水事件空间集中度指标，结合气象背景分类和最优指纹法等方法，阐明降水事件空间集中度的特征及主要控制因素；然后采用最新的共享社会经济路径框架下的CMIP6模式结果和城市扩张产品，利用虚拟全球变暖方法驱动WRF数值天气模式，预估不同气候变化和城市化发展情景下极端降水事件空间集中度的未来变化规律。研究结果有助于理解和预测极端降水事件的变化特征，为制定城市洪涝灾害的调适策略提供科学依据。

Spatial concentration of extreme precipitation events will increase the risk of flood disasters and bring crucial impacts on society and human life. The concentration of precipitation events is likely to be intensified under the superimposed effects of global warming and urbanization. However, our understanding on the spatial concentration of precipitation events over typical metropolitans remains very limited. Taking the rapidly developing Pearl River Delta region as an example, this project focuses on the following two scientific questions: (1) patterns and impact factors of the spatial concentration of precipitation events under different synoptic conditions, and (2) future changes in the spatial concentration of precipitation events under different climate change and urbanization scenarios. First, a concentration ratio (CR) grounded on the Gini index will be designed to quantify the spatial concentration. Clustering analysis and optimal fingerprint detection will be employed to clarify the features and the driving factors of CR under different synoptic conditions. A pseudo global warming approach which is based on the CMIP6 results and a scenario projection of global urban expansion will be applied to drive the Weather Research and Forecasting (WRF) model for dynamic downscaling simulations under the framework of shared socioeconomic pathways (SSPs). The possible future changes of CR, as well as the impacts of climate change and urbanization on the spatial concentration of extreme precipitation events, will be estimated under the different SSP scenarios. Our results have implications for better understanding and projection of changing extreme precipitation events, which provide a scientific basis for urban flood disaster management and mitigation over the Pearl River Delta.