A Multidimensional Framework for Resilient Wastewater Systems: Linking Spatial Flood Hazard, Circularity, and Financial Bankability

Wastewater treatment plants (WWTPs) face increasing climate-change-induced flooding, yet flood resilience is seldom integrated into design, operation, or investment decisions. This study presents a multidimensional framework to support climate-resilient, circular, and bankable wastewater infrastructure planning. The methodology combines spatial flood exposure mapping using QGIS and Aqueduct flood layers for 2030, 2050, and 2080 with a 142-indicator Circular Economy (CE) scoring framework. Applied to five WWTPs in Türkiye, we develop the Index for Climate Risk and Circularity (ICRC), linking facility-level circularity performance with physical flood exposure. The results show that some technically advanced facilities achieve relatively high CE scores while remaining exposed to partial or near-complete inundation under future 1000-year flood scenarios, particularly in coastal areas. By connecting flood exposure, circularity, and operational cost reduction potential, the framework translates technical sustainability improvements into investment-relevant metrics for utilities, engineers, and financiers. It shows that circularity investments (e.g., renewable energy, resource efficiency) strengthen bankability only when combined with physical climate adaptation. Robustness checks, including alternative weighting assumptions and a cross-facility comparison, suggest that the main investment-prioritization logic remains broadly stable. The framework provides a replicable decision-support tool for prioritizing investments that enhance circularity, climate resilience, and long-term financial viability, while supporting the Sustainable Development Goals (SDGs) 6, 9, 11, and 13.