Urbanization Amplified Asymmetrical Changes of Rainfall and Exacerbated Drought: Analysis Over Five Urban Agglomerations in the Yangtze River Basin, China

• Published in: Earth's future Vol. 11; no. 2
• Main Authors: Huang, Shuzhe, Gan, Yuan, Zhang, Xiang, Chen, Nengcheng, Wang, Chao, Gu, Xihui, Ma, Jingjin, Niyogi, Dev
• Format: Journal Article
• Language: English
• Published: Bognor Regis John Wiley & Sons, Inc 01.02.2023; Wiley
• Subjects: Anthropogenic factors; Asymmetry; Climate change; Climate models; Cognition & reasoning; Drought; Extreme weather; Global warming; Heavy rainfall; Human influences; Humidity; Hydrologic cycle; Hydrology; Mathematical models; Meteorological research; Precipitation; Rain; Rain and rainfall; Rainfall; Rainy season; River basins; Rivers; Rural areas; Urban areas; urban droughts; urban extremes; Urban planning; Urbanization; Weather; Weather forecasting; Yangtze River Delta; China; Yangtze River
• ISSN: 2328-4277; 2328-4277
• DOI: 10.1029/2022EF003117

Urbanization has become a prominent anthropogenic activity globally, resulting in the substantial modification of temperature and rainfall in and around urban areas. Studies also indicate that rainfall exhibits an asymmetrical shift from light to extreme rainfall, causing both floods and droughts over different parts of the globe. However, to what extent urbanization influences the asymmetrical changes in rainfall and urban drought remains understudied. Accordingly, we provided an investigation of the urbanization effects on both rainfall and drought events from both statistical and model‐based perspectives. Results showed that urbanization generally increased heavy rainfall and decreased light rainfall in the rainy season over five urban agglomerations (i.e., Yangtze River Delta [YRD], Middle Region of Yangtze River [MRYR], Chengdu‐Chongqing, Guizhou, and Yunnan) in the Yangtze River Basin during 1981–2020. Specifically, urbanization contributed 42.7% and 30.8% of the increases of heavy rainfall in MRYR and YRD while 30.6% contribution to the decrease of light rainfall. Interestingly, results suggested that the urban regions were more prone to drought due to urbanization. Nevertheless, we also found that the urbanization effects showed some variabilities across different areas due to the interactions with complex terrains and climate patterns. Further model‐based simulations using the Weather Research and Forecasting model confirmed our findings and helped understand the potential underlying mechanism. The current research is expected to provide scientific knowledge for better urban planning and preparedness for urbanization‐induced hazards. Plain Language Summary The Yangtze River Basin (YRB) has experienced rapid urbanization in recent decades, accompanied with increases in heavy rainfall, decreases in light rainfall, and prolonged dry days. However, how urbanization modifies the asymmetrical changes of rainfall and urban drought remains unknown. Here we investigate the changes of rainfall and drought over five urban agglomerations in YRB and quantify the effects and relative contribution of urbanization to these changes. Over the period of 1981–2019, urbanization tends to increase heavy rainfall, suppress light rainfall, and exacerbate drought. Results show that urbanization contributes 42.7% and 30.8% of the increases of heavy rainfall in the Middle Region of Yangtze River and the Yangtze River Delta while 30.6% contribution to the decrease of light rainfall over five urban agglomerations. Key Points The urbanization effects on rainfall and drought were investigated over five urban agglomerations in the Yangtze River Basin, China Urbanization tended to increase heavy rainfall, suppress light rainfall, and exacerbate drought Statistical methods and Weather Research and Forecasting‐based simulations further confirmed the urbanization effects on rainfall and drought