Optimized strategies of green and grey infrastructures for integrated control objectives of runoff, waterlogging and WWDP in old storm drainages

Lijun Xiong; Shiqiang Lu; Juan Tan

doi:10.1016/j.scitotenv.2023.165847

Optimized strategies of green and grey infrastructures for integrated control objectives of runoff, waterlogging and WWDP in old storm drainages

Sci Total Environ. 2023 Nov 25:901:165847. doi: 10.1016/j.scitotenv.2023.165847. Epub 2023 Jul 30.

Authors

Lijun Xiong¹, Shiqiang Lu², Juan Tan³

Affiliations

¹ Shanghai Academy of Environmental Sciences, Shanghai 200233, China. Electronic address: xionglj@saes.sh.cn.
² Shanghai Academy of Environmental Sciences, Shanghai 200233, China. Electronic address: Lusq@saes.sh.cn.
³ Shanghai Academy of Environmental Sciences, Shanghai 200233, China. Electronic address: Tanj@saes.sh.cn.

PMID: 37527707
DOI: 10.1016/j.scitotenv.2023.165847

Abstract

Frequent waterlogging occurs in old high-density urban areas where the sewage is inappropriately connected to storm drainages, resulting in serious wet weather discharge pollution (WWDP). To address urban waterlogging and runoff, the optimization of green infrastructures (GIs) and grey infrastructures (GRs) has been proposed to improve rainwater management efficiency. However, most strategies neglect WWDP and fail to achieve integrated control of runoff, waterlogging, and discharge pollution. In the present study, a new optimization method was introduced to identify optimal solutions for renovating outdated storm drainage systems, considering the management of discharge pollution in wet weather. A case study in Shanghai, China was conducted to demonstrate the application of the method. The cost-benefit index (CBI) of optimized GIs (0.06) was lower than that of optimized GRs (2.78) under 22.2 mm rainfall (no runoff and WWDP), but the costs of the former were only half those of the latter. In a 5-year return period storm (no waterlogging), optimized GIs had a significantly higher CBI (2.85 times) compared to optimized GRs, costing only 44 % of the latter. When WWDP reached the control objective (COD≤70 mg/L), the optimized GIs needed to be further optimized with GRs. The CBI of optimized GI-GRs was higher than GRs by 2.50, and the cost was 58% of the latter. In areas with frequent low-intensity rainfall, optimized GIs and GRs should be selected based on local cost or benefit requirements for drainage reconstruction. In high-intensity storm-prone areas, the optimized GI-GR combination should be selected for drainage reconstruction. The proposed method can compensate for the shortcomings of existing optimization methods in controlling WWDP for the reconstruction of old storm drainages.

Keywords: Green infrastructures (GIs); Grey infrastructures (GRs); Integrated control of runoff; Old storm drainages in high-density urban areas; Optimized strategies; Waterlogging and WWDP; Wet weather discharge pollution (WWDP).