Assessment of Flood Control Effectiveness of Green-Grey-Blue Infrastructure During Extreme Rainstorms:A Case Study of East-sha Lake Watershed

To address the limitations of urban flooding studies,which mainly focus on a single green or grey infrastructure or green-grey infrastructure,we modeled the East-sha lake watershed in Wuhan based on a coupled hydrological-hydrodynamic model.We generated extreme rainfall scenarios with return periods of 1~1 000 years by using the Wuhan rainstorm formula and transplanting the Zhengzhou “7·20” rainstorm event.We analyzed the stormwater control capacity of green-grey-blue infrastructure under extreme rainstorms.The results show that the green infrastructure is efficient for rainfall of 1~5 years,and provides peak shaving and peak delaying effects.The optimization of grey infrastructure helps the city to cope with extreme rainstorms,and its effect is more obvious the higher the rainfall intensity,but it has the negative effect of increasing the peak value and advancing the peak time.Blue infrastructure has great potential for stormwater storage and can provide protection against extreme rainstorms,but its comprehensive benefits need to be considered in the development of multi-level water level control plan.It is necessary to integrate the green-grey-blue infrastructure to optimize the assessment,which is because the backwater effect reflects their hydraulic connection and coupling relationship.This study can provide scientific basis for urban flood disaster management and sponge city construction planning.