Comprehensive analysis of waterlogging control and carbon emission reduction for optimal LID layout: a case study in campus

Nowadays, sponge city reconstruction has become the focus of research because of the increasingly serious urban waterlogging. Carbon emission reduction, waterlogging area reduction, cost, and other indicators were considered to explore the optimal sponge allocation scheme in the study area. The two-dimensional coupled model MIKE FLOOD was established to analyze the causes of waterlogging through numerical simulation. Low-impact development (LID) combination scenarios were set to analyze the control effects of waterlogging water and total runoff. The carbon emission reduction capacity and economic benefit of each scenario were calculated and evaluated. The analytic hierarchy process (AHP) was used to comprehensively evaluate the LID combination scenario and explore the optimal cost–benefit LID configuration scheme. The results show that the campus rainwater pipe network is under overload operation, and the number of overflow nodes accounts for up to 58.1% under the 3a rainfall return periods. After setting up LID measures, the runoff control rate can be increased by 26.15–42.84%, and the waterlogging area where the depth exceeds 15 cm can be reduced by 72.87–100%. If the energy conservation and emission reduction benefits and costs are considered at the same time, the layout scenario of 9% bioretention facility + 3% green roof + 3% permeable pavement can achieve the best benefits. The research can provide a reference for planning and reconstruction of sponge campus and residential areas.