Monitoring and health evaluation of stormwater runoff processes: A case study of Handan metropolis, North China

Metropolitan areas are facing increasing environmental risks of urban flooding under changing climate and intensified human activities. Therefore, it is of vital importance to evaluate the health of processes of stormwater runoff in changing environment. In this paper, the health evaluation was conducted using an indices system integrating the Analytic Hierarchy Processes (AHP) and Key Performance Indices (KPI) methods. This system consists of four dimensions, i.e. rainfall, runoff generation, runoff routing and river retention, and 12 indicating indices, considering the impacts of urban development on water cycling processes. Case study was conducted in Handan metropolis, North China. Particularly, an extreme stormwater runoff event, i.e. "2017.06.21 Stormwater Event", one of the most severe and typical urban stormwater events recently, was analysed. Results showed that the processes of stormwater runoff in this study rest in a sub-health state. The production processes is the most critical link in the urban water cycling health assessment. This result maps out the problem of poor infrastructure construction in Handan metropolis. Methods and results of this study could help better understanding of urban stormwater management and could serve as a reference for health evaluation of urban flooding in other metropolitan areas.