Spatiotemporal responses of event-based extreme precipitation to urbanization in major urban agglomerations of China

This study focuses on six major urban agglomerations (UAs) in China: the Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), Pearl River Delta (PRD), Chengdu-Chongqing (CC), Central China (CCR), and Harbin-Changchun (HC) regions. Leveraging high-resolution hourly precipitation records from 1985 to 2021, this study examines the intensity (maximum and average), amount, duration, and frequency of extreme precipitation events (EPEs) and their spatiotemporal evolution across these six UAs, highlighting regional contrasts shaped by distinct climatic and environmental contexts. Across the six UAs (1985–2021), event amount increases consistently and frequency shows a weak but generally positive rise, whereas intensity diverges regionally—average intensity strengthens in humid PRD/CC/YRD but weakens or remains stable in semi-humid BTH/HC/CCR. Maximum intensity can decouple from average intensity, with PRD showing a pronounced increase in peaks. Duration further differentiates regions, decreasing in PRD but increasing or remaining near-stationary elsewhere. Urbanization effects are metric- and UA-dependent, strongest for amount, weaker for duration and intensity, and minimal for frequency, underscoring coupled climate–urban controls and the need for region-specific risk assessment. • Hourly data (1985–2021) used to extract extreme precipitation events in six Chinese urban agglomerations. • Urbanization amplifies precipitation amount most, while frequency shows weak response. • EPE intensity diverges: humid UAs increase, semi-humid urban agglomerations stable or declining.