Design and Evaluation of Green Space In Situ Rainwater Regulation and Storage Systems for Combating Extreme Rainfall Events: Design of Shanghai Gongkang Green Space to Adapt to Climate Change

Global climate change has led to more extreme rainfall events. Exploring the different design schemes of rainwater in situ regulation and storage systems in green spaces to cope with extreme rainfall events is critical to cities for combating flood disasters. Using the Gongkang green space as the research object and the XPDrainage software program as the simulation tool, this study explored and evaluated different design schemes of rainwater in situ regulation and storage systems in green spaces and their responses to extreme rainfall events in Shanghai. Based on the simulated results of the runoff curves, paths and ponding area of the Gongkang green space, the ideal number and position of rainwater regulation and storage facilities were determined. Four different schemes were examined: Scheme A (diversion-oriented), Scheme B (infiltration- and detention-oriented) and schemes C and D (comprehensive rainwater regulation and storage systems). From the simulation evaluation, the total runoff volume capture rate of Scheme C reached 100%, 99.8% and 98.2% under one-, three- and five-year return period rainfall events, respectively. For the 210 mm extraordinary rainstorm event, Scheme C’s and Scheme D’s total runoff volume capture rates reached 81.9% and 94.7%, respectively. Therefore, the comprehensive rainwater regulation and storage schemes (schemes C and D) met the runoff control requirements under extreme rainfall events in the Gongkang green space. This study provides a technical reference for the optimal design of a rainwater in situ regulation and storage system in a green space and promotes the construction of resilient cities.