Assessing the consistent and divergent impacts of urbanization on heavy rainfall in Chinese urban agglomerations

Understanding the impact of urbanization on extreme precipitation is crucial for promoting sustainable urban development in the context of global warming and rapid urban expansion. Here we found the highest impacts in humid regions such as the Yangtze River Delta and Pearl River Delta, where urbanization amplifies extreme rainfall intensities, varying with the rate of urbanization across the representative cities. Moreover, the impact is greater at the 3-hourly scale compared to the daily scale in most cities in humid regions. However, we found no significant impact of urbanization on extreme rainfall across continental climate regions like the Beijing-Tianjin-Hebei. Furthermore, we also found that urbanization alters the trends of heavy rainfall during daytime and nighttime, with significant regional variations linked to impervious surface coverage. Our findings provide essential scientific evidence to assist cities in designing targeted disaster mitigation policies, especially for those with diverse contexts and development patterns. Urbanization amplifies extreme rainfall intensities in humid regions like the Yangtze River Delta and Pearl River Delta, with varying impacts based on urbanization rates, according to analysis of rainfall trends across different cities and climate regions.