Cities struggle to measure whether green stormwater projects actually work
A new study reveals a critical gap: while cities increasingly adopt nature-based solutions like rain gardens to manage flooding, they lack consensus on how to measure whether these projects deliver promised benefits. The finding exposes a governance problem that could undermine billions in climate adaptation spending unless municipalities standardize their assessment approaches.
Originaltitel: Making sense of indicators for nature-based solutions in sustainable stormwater management: A governance-aware screening approach
Nature-based solutions are increasingly promoted in sustainable stormwater management to deliver multifunctional benefits. Translating these ambitions into decision-relevant assessments remains challenging, particularly for governance and socially oriented indicators, understood in this study as assessable prompts that capture broader governance and context-related decision conditions. Positioned within indicator-based sustainability assessment, this study develops and applies a governance-aware screening approach to support early-stage selection, interpretation, and sense-making of indicators in real decision contexts. In an expert survey, municipal practitioners and researchers assessed 40 indicators for two contrasting catchment cases under two dimensions: Relevance and Resources. Rather than ranking indicators, the analysis focuses on how judgments emerge when indicators are interpreted against catchment-specific technical and institutional contexts. Results show strong convergence in perceived Relevance across cases, while Resources judgments are more uncertain for socio-organizational and land-use related indicators, reflecting an operationalization gap resulting from interpretive ambiguity, institutional variability, and capacity constraints. This mismatch pattern suggests that indicator judgments are co-produced by land ownership, use rights and actor constellations within each catchment context. While Relevance–Resources patterns remain context-shaped, the screening logic is transferable as a pre-assessment indicator scoping step. The governance-aware approach clarifies Relevance–Resources trade-offs when interpreting indicators early in decision-making, complementing hydrological, technical, and economic evidence in sustainability assessment. • Governance and social indicators remain hard to operationalize in assessments. • A screening approach supports early-stage sense-making of indicators selection. • Relevance–Resources mismatch reveals operationalization gaps. • Resources uncertainty clusters in socio-organizational indicators. • The transferable logic clarifies trade-offs and complements hydrological and economic evidence.