A novel multi-objective optimization framework for urban green-gray infrastructure implementation under impacts of climate change.

Frequent urban flooding disasters can cause severe economic and property losses. Accordingly, the construction of sponge city has become critical to alleviating urban flooding. However, the functional and structural integration of Green Infrastructure (GI) and Gray Drainage Facility (GDF) is still a matter of concern. This study proposed a novel implementation framework for GI and GDF synchronization optimization (G-GSOIF) based on the SWMM and SUSTAIN models, and used data from Beilin District in Xi'an, China to verify the effects. The results show that the spatiotemporal integrated optimization design of GI and GDF proves to be effective in stormwater management. The total investment was reduced by 16.7% and economic benefit was increased by 15.4% based on disaster risk control, and the utilization rate of rainwater resources exceeded 40%. The Staged optimization model (SSOM) based on the SUSTAIN model established in the G-GSOIF was demonstrated to effectively cope with the impact of future climate change by adjusting and optimizing the design scheme dynamically in different simulation scenarios. Integrated LID (I-LID) measures are conducive for simulation of large catchment areas, and have the same implementation effect as distributed LID measures. The results of this study could support decision-making for urban stormwater management and sponge city construction.