Optimization of integrating life cycle cost and systematic resilience for grey-green stormwater infrastructure

•A multi-objective optimization and analysis framework for HGGI is proposed.•A trade-off between costs and systematic resilience for HGGI design is developed.•The HGGI layouts with different degree of decentralization is compared.•Importance of spatial allocation for HGGI is highlighted in different urban areas. The trade-offs for alternative grey-green infrastructure (HGGI) solutions between life cycle cost (LCC) and systematic resilience may impose many limitations in planning and implementation of urban stormwater strategies in high-dense urban catchment. This study presents a generic approach in the context of a multi-objective optimization, with the aim to (1) optimize and design HGGI under various uncertainties, and conflicting objectives (e.g., LCC, technological and operational resilience); and (2) determine the trade-offs between the multi-objectives and degrees of system decentralization in areas with various development intensities. Taking two areas in Guangzhou, China, as case studies, this study shows that decentralized HGGI exhibits economic advantages. However, to maintain a high systematic resilience in high-density catchments, it is often necessary to rely on solutions with high degree of centralization, which may incur higher cost. HGGI is found to perform better in terms of technological resilience under extreme storms, than operational resilience to the uncertainty associated with structure performance. In addition, porous pavement is found to exhibit high potential for wider application compared to bioretention cells as green infrastructure in HGGI. The framework developed in this study could support decision-making for stormwater management via enhancing both hydraulic reliability and hydrologic resilience. [Display omitted]