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Heavy precipitation, which is changing significantly as Earth's climate warms, can result in flooding that seriously damages societies. However, little is known about how heavy precipitation of varying durations responds to the diverse gradients of urban development in China. Through statistical analyses spanning from 1990 to 2021, we have examined shorter‐duration (≤3 days) and longer‐duration (>3 days) heavy precipitation across a spectrum of urban development, encompassing long‐term built‐up (LTB), recently built‐up (RTB), and rural background catchments within each urban agglomeration catchment (UAC) across China. We find that urbanization primarily influences shorter‐duration heavy precipitation, with a more pronounced effect observed in the LTB catchments. Conversely, the influence of urbanization on longer‐duration heavy precipitation appears to be more weakened in the RTB catchments. The intensification of shorter‐duration heavy precipitation induced by urbanization is more pronounced in humid regions and within larger UACs, while the urban effect on longer‐duration heavy precipitation is weaker in humid regions and within larger UACs. Notably, the attribution analysis results of the geographical detector model confirm our findings. Anthropogenic‐related factors (population density, nighttime light data, impervious surface percent, land surface temperature) significantly influence shorter‐duration heavy precipitation in more UACs than natural factors (distance from the coast, wind and elevation), while natural factors dominate longer‐duration events in larger UACs across China. Our results highlight the necessity of considering the spatial difference between the UAC center and UAC periphery for accurate projections and effective prevention of heavy precipitation and potential flood risks in the future. Plain Language Summary: Heavy precipitation can lead to severe flooding, causing substantial damage to communities. However, understanding how heavy precipitation, varying in duration, responds to different urban development scenarios in China remains limited. We conduct a thorough analysis from 1990 to 2021, exploring shorter‐duration (up to 3 days) and longer‐duration (over 3 days) heavy rainfall across a range of urban settings. Urbanization notably impacts shorter‐duration heavy rainfall, particularly in long‐term built‐up areas, and its influence weakens in recently built‐up regions for longer‐duration heavy rainfall. The amplification of shorter‐duration heavy rainfall due to urbanization is more significant in humid regions and larger urban areas, while the impact on longer‐duration heavy rainfall is less pronounced in humid regions and larger urban areas. Our findings emphasize the need to account for spatial differences within urban agglomerations for accurate projections and effective prevention of heavy rainfall and potential flood risks in the future. Key Points: A catchment‐based strategy is proposed to analyze the heavy precipitation changes in response to urbanizationUrbanization tends to increase shorter‐duration heavy precipitation but has a weaker effect on longer‐duration heavy precipitationAnthropogenic‐related factors drive shorter‐duration heavy precipitation in more UACs, while natural factors dominate longer‐duration events [ABSTRACT FROM AUTHOR]

Moisture sources and transport processes play a critical part in hydrological cycle and determine regional precipitation. This paper utilizes the Water Accounting Model‐2layers (WAM‐2layers) and the ERA5 reanalysis data to track the sources of precipitation over the Pearl River Basin (PRB). The contribution of external moisture and the role of local recycling are investigated. The results show that during the period from 1980 to 2020, oceanic sources including the western North Pacific and Indian Oceans serve as the primary moisture sources of precipitation over the PRB. The contributions to total seasonal precipitation are respectively 62.57% in MAM, 54.79% in JJA, 43.70% in SON and 60.88% in DJF. By contrast, the contribution of local recycling is generally below 5.50%. In the dry years of 1994, 1997 and 2001, the contribution of terrestrial sources is about 19.22%; in the wet years of 1989, 2009 and 2011, the contribution is about 16.31%. The summer precipitation anomalies are mainly attributable to moisture anomalies from the Equatorial Indian Ocean in the wet years and from Southeast Asia in the dry years. Furthermore, vertically integrated moisture flux anomalies over the boundaries of the PRB are generally the result of anomalous wind rather than anomalous moisture. In the wet years, low‐pressure systems induce strong cyclonic moisture transports, increasing the PRB precipitation. In the dry years, high‐pressure anomalies over the PRB block the moisture transports from the Indian Ocean and western North Pacific. [ABSTRACT FROM AUTHOR]