Nature-based solutions for urban water management

The traditional means of urban water management relied heavily on engineering measures, or the use of “gray” infrastructure. Recently, there has been a call to integrate green infrastructure. This study conducts a systematic survey to characterize various nature-based solutions (NBS) adopted in different regions of the world and to elaborate on the benefits and limitations. It highlights the role of NBS in urban flood risk management under ongoing climate change and rapid urbanization. It shows that NBS could effectively mitigate urban flooding caused by high-frequency precipitation events, with additional economic, ecological, and social benefits. However, NBS are less effective at helping cope with pluvial flooding caused by extreme precipitation events over a short period of time, while gray infrastructures also have limitations as a mitigation measure against extreme pluvial flooding. It is thus recommended that integrating green and gray infrastructure is critical for urban water management, in particular with deep uncertainty in future.