Supply-demand measurement and spatial allocation of Sponge facilities for Sponge city construction

Sponge City Construction (SCC) has been extensively explored for controlling frequent urban waterlogging and non-point source pollution. Assessing the "supply" and "demand" of SCC as a city-wide approach may aid in appropriate areal coverage to achieve optimal performance on flood control based on local priorities and sus-tainable urban development plans. However, to date, very few studies have examined the potential spatial mismatches in the "supply" and "demand" of SCC. This study presented the development of a framework to explore the supply-demand relationship based on a spatial multi-criteria evaluation of the existing SCC facilities, risk exposure, and socio-economic vulnerability. The feasibility and application of such a framework were successfully demonstrated in a field application in Guangzhou, China. The results indicated that most of the high -density areas in the city centres of Guangzhou were exposed to high risk with strong SCC demands. Furthermore, Liwan and Yuexiu districts exhibited SCC supply deficits, while SCC supply surpluses were observed in other central districts in Guangzhou. The findings of this study provided insight into the development of a generalised and replicable method that could be used to achieve a balance between the "supply" and "demand" of SCC for more participatory, strategic and multifunctional planning of SCC in various urban contexts.