Impacts of Spatial Layout of Green Infrastructure in Urban Residential Areas on Surface Runoff During Long- and Short-Duration Rainfall Intensity: A Case Study in Wuhan, China

Owing to the frequent occurrence of extreme weather triggered by ongoing climate change and progressively accelerating urbanisation, urban stormwater management has become a critical issue. Under such circumstances, Green Infrastructure (GI) has steadily become a sustainable way to mitigate urban flooding disasters. For this reason, it is essential to look into the dissimilar regulatory roles of GI under long- and short-duration rainfall intensity, especially in mega cities with continuous rainfall. Wuhan is located in a temperate region in the middle and lower reaches of the Yangtze River, featuring such rainfall intensities. This study selected 43 typical residential areas in Wuhan and combined buildings with GI, which generalised them as three major types of GI spatial layouts, namely Freestanding, Attached, and Mixed layouts. Through K-means clustering and multiple linear regression analyses, the peak flow, final water storage, and integrated runoff coefficients of dissimilar spatial layouts were analysed in a systematic manner. As suggested by the research findings, we ultimately reach the following conclusions: ① In the Freestanding spatial layout, the combination of distributed green space and pavilion buildings has the optimal rainfall resilience under long- and short-duration rainfall intensity. ② In the Mixed spatial layout, the integration of distributed green space and enclosed buildings has the best rainfall resilience under long- and short-duration rainfall intensity. ③ In the Mixed spatial layout, the combined roof type has short-duration rainfall resilience, while the combined vertical type has long-duration rainfall resilience. Integrating the surface runoff impacts of diverse spatial layouts for long-and short-duration rainfall intensity, a conclusion can be reached that the combination of distributed green space and distributed enclosed buildings is most suitable for Wuhan residential areas. The quantifiable methodology adopted in this study can be generalised and applied to other regions with similar climatic characteristics and urban morphology, providing a scientific basis for the construction of sponge cities and resilient cities.