Effect of sponge city construction on urban waterlogging reduction in semi-humid areas of China

Abstract

Abstract Urban waterlogging frequently occurs in semi-humid areas due to the short duration of heavy rainfall in summer and the high rates of subsurface hardening caused by high-intensity urban development. To solve the problem of urban waterlogging, China has launched the construction of ‘sponge cities’ and made some progress, but there is still a lack of comprehensive consideration of the functional types and spatial layout of low impact development (LID) facilities. Qian'an, a city of Hebei Province, is one of the first sponge city pilot cities in China. This paper focuses on Yanshan South Road and its surrounding areas, a historical waterlogging section of Qian'an city. Four common LID measures (sunken green space (SG), bioretention ponds (BP), infiltration ponds (IP), and reservoirs (RE)) in two function types are selected and combined through centralized (CE) and decentralized (DE) different spatial layouts, a total of 80 design scenarios are proposed. Then, using the storm water management model (SWMM) to calculate the effect of each scheme on peak flow reduction under different rainfall return periods. The results showed that all LID scenarios can effectively alleviate the urban waterlogging problem, among which the schemes of DE-SG-BP (1:1), DE-IP-SG (1:1), DE-SG-IP (3:1), DE-SG-IP (1:3), and DE-SG-BP (3:1) had the highest peak flow reduction rate, up to 95.46%. The schemes of CE-RE-IP (3:1) and CE-IP-RE (3:1) had better hydrological performance in occupying less surface space, with a peak flow reduction rate of 8.68% per square meter. Therefore, the distributed layout combined with infiltration LID facilities and storage LID facilities can be used in urban built-up areas with limited land use conditions, which has a more obvious effect on reducing waterlogging.