An integrated framework to select resilient and sustainable sponge city design schemes for robust decision making

To mitigate the impacts of rapid urbanization and climate change on hydrology and water quality, the new concept of urban stormwater management, sponge city, has been proposed to increase the city's resilience. Although 30 cities in China have been chosen to implement sponge city construction, there is a lack of a quantitative evaluation method to help decision makers select resilience and sustainability schemes. This paper proposes a new integrated framework in selecting the resilient and sustainable sponge city design schemes. The developed framework consists of the following 10 indicators: resilience, flood volume, flood duration time, hydraulic performance index, annual runoff volume control, rainfall usage, pollution control, social acceptability, greenhouse gas emission, and cost. The Storm Water Management Model (SWMM) was used to simulate the rainfall-runoff process to calculate the indicators. The multi-criteria analysis methods of the improved AHP were used to calculate the weights of indictors, while the technique for order preference by similarity to ideal solution (TOPSIS) was used to rank the design schemes. The proposed framework was then applied to Xining, China, as a case study. The performances of three sponge city design schemes (51, S2, and S3) with different sponge city construction areas and different low impact development (LID) controls were analyzed for the LID construction project. The results identified 51 as the best scheme where 50% permeable pavement and 30% rain barrel are implemented in residential areas. In contrast, S3 had the lowest scores, with the largest LID construction area. This integrated framework will assist policy-makers in the selection of optimal sponge city design schemes.