Urbanization Enhances Shorter-Duration Precipitation Intensity in the Yangtze River Delta Region

Abstract

Understanding the response of extreme precipitation events under urbanization conditions is vital for mitigating the risk of urban flooding. Nevertheless, previous studies assessing the impact of urbanization on extreme precipitation often neglected the role of natural climate variations. To fill this gap, this study aims to investigate how extreme precipitation of varying durations responds to urbanization, accounting for natural climate variations. We classified the urban agglomeration of the Yangtze River Delta (YRD) in East China into nine distinct groups based on seasonal extreme precipitation patterns, utilizing structural self-organizing maps (SOM), and explored the relationship between urbanization and extreme precipitation with Geographical Detector Model. The results revealed substantial seasonal precipitation fluctuations within the YRD, showing significant spatial variability and underscoring the importance of considering natural climate variations in urban extreme precipitation studies. After accounting for natural climate variations, our findings unveiled a notable urbanization-induced precipitation effect, particularly prominent during summer and autumn. Additionally, urbanization's influence on extreme precipitation demonstrated a significant time-scaling effect, with shorter-duration events exhibiting a stronger correlation with urbanization. Furthermore, the interaction between urbanization and elevation surpassed the impact of individual factors, intensifying as event duration decreased, especially for durations less than 3 days, indicating a more complex mechanism for their influence on extreme precipitation. This research aims to enhance our understanding of how urbanization shapes extreme precipitation patterns. These findings are crucial for urban planning and climate adaptation strategies to address the risks associated with heavy precipitation in urban areas.