<p>Relative sensitivity of the criterion.</p>

Rapid urbanization and climate variability in Addis Ababa’s steeply sloped watersheds—characterized by poorly draining Vertisol soils and high impervious cover—have increasingly overwhelmed stormwater infrastructure, resulting in frequent flooding and erosion. To address the lack of systematic performance data, this study conducted a systematic performance evaluation of 30 representative stormwater infrastructure units across five spatially delineated blocks within a 30-hectare urban micro-watershed in Addis Ababa, Ethiopia. The objective was to develop an evidence-based framework for prioritizing maintenance and green infrastructure (GI) retrofitting interventions. Six critical performance criteria—flood conveyance capacity, structural integrity, erosion control effectiveness, sediment accumulation, maintenance accessibility, and flood control effectiveness (from hydrologic modeling)—were assessed through structured field inspections and Personal Computer Storm Water Management Model (PCSWMM) simulations. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), integrated with expert-derived weights from the Analytic Hierarchy Process (AHP), was applied to rank the five blocks. A comprehensive sensitivity analysis tested ranking robustness against five alternative weighting scenarios. Results showed that sediment accumulation and flood conveyance capacity emerged as the most influential criteria. Spearman’s rank correlation coefficients exceeded 0.92 in all cases, confirming strong ranking stability. Block 3 achieved the highest performance score (Cᵢ = 0.7), while Block 4 ranked lowest (Cᵢ = 0.43) due to structural deficiencies and sediment buildup. The analysis revealed that 42.3% of the study area is ready for GI retrofitting, while 57.7% requires prioritized maintenance and rehabilitation. The TOPSIS–AHP–PCSWMM framework provided a transparent, evidence-based mechanism for prioritizing interventions, offering practical insights for optimizing stormwater management in Addis Ababa and comparable data-scarce urban environments in the Global South. This work supports the United Nations Sustainable Development Goals (UN-SDGs) 11 (Sustainable Cities), 12 (Responsible Consumption), and 13 (Climate Action).