ABSTRACT This study presents a replicable methodology for assessing the multi-benefit performance of nature-based solutions (NBSs) in urban stormwater management. The framework quantifies four benefits – flood risk reduction, water quality improvement, urban heat mitigation, and public well-being – using grid-based spatial analysis, hydrological simulations (Stormwater Management Model (SWMM)), design-based water purification analysis, and land cover classification. The method was tested on seven pilot sites across Estonia, Sweden, Finland, and Latvia. Flood mitigation was evaluated using both passive and real-time control (RTC) designs. RTC systems achieved up to 3.8 times greater flood reduction coefficients compared to passive systems. Water quality improvements were highest at sites with large surface areas and extended flow paths, with sediment and nitrogen removal rates reaching up to 95%. Urban cooling benefits were linked to high water and vegetation coverage, while public well-being was maximised in areas with multifunctional public spaces. Economic analysis using the present value (PV) and benefit-cost ratio (BCR) showed BCR values ranging from 1.28 to 3.62, confirming strong financial viability.The proposed methodology supports early-stage planning and investment in multifunctional NBSs by providing quantifiable, site-specific performance indicators. It offers a practical decision-support tool for urban planners and policymakers seeking integrated solutions for climate resilience.
Kõiv et al. (Fri,) studied this question.