Integrated evaluation and attribution of urban flood risk mitigation capacity: A case of Zhengzhou, China

Study region: The Zhengzhou City in China Study focus: Urban flood risk mitigation (UFRM) refers to the runoff retention capacity of land surface in urban regions. Previous studies have focused on assessing the UFRM change in central urban areas. Nevertheless, analysis of the UFRM change considering the heterogeneity of urban and rural gradient is scarce. This study aims to evaluate the spatiotemporal change of UFRM and its influencing factors in different urban functional zones. An integrated framework combining the hydrological model and geographic information system (GIS) has been established to assess the evolution of UFRM in Zhengzhou between 2000 and 2020. New hydrological insights for the region: The findings illustrate the following: (1) The UFRM of Zhengzhou experienced a 10.76% increase from 2000 to 2010, followed by a subsequent 3.38% decrease from 2010 to 2020.(2) UFRM increased in ecological areas while decreasing in urban regions, revealing a disparity between UFRM supply and demand. (3) The adverse impact of impervious surfaces on UFRM surpasses the influence of precipitation intensity in urban regions. As a result, this study suggests that urban areas should avoid extensive expansion of impervious surfaces and prioritize implementing low-impact development practices. The ecological zones should implement rigorous policies to protect natural preservation. These findings provide policymakers a scientific foundation for devising sustainable urban development strategies to enhance urban flood resilience.