Steeper spatiotemporal distribution of extreme precipitation intensity in urban than rural regions

Urban flooding is highly sensitive to the organization of precipitation—its intensity, timing, spatial extent, and concentration. However, it remains unclear how urbanization alters these structure-related characteristics of extreme precipitation across time and space. Here, in the case of the Yangtze River Delta urban agglomeration of East China, we examine the urbanization-induced asymmetric spatiotemporal reorganization of extreme precipitation during the rainy season (May–September) from 1979 to 2015. Urban extreme precipitation events show less uniform temporal evolution than rural counterparts, characterized by sharper peaks, suppressed flanks, and faster post-peak attenuation. Spatially, these events display more heterogeneous patterns with centralized intensification and peripheral weakening. This reorganization is driven temporally by greater warming and stronger peak-precipitation response in urban regions, and spatially by extensive urban expansion that contracts the spatial extent of extreme precipitation while amplifying its central intensity. These findings improve our understanding of how urbanization reshapes the spatiotemporal structure of extreme precipitation and provides insights for improved flood preparedness and water resource management in rapidly developing urban regions.