Blue-green infrastructure for climate adaptation: a socio-economic assessment of decentralised rain-water management measures in the urban environment

Abstract. This study assesses decentralised blue-green infrastructure measures for urban climate adaptation in Berlin and Cologne using a dual approach that combines multi-criteria analysis and cost–benefit analysis. Twenty sustainable urban drainage system variants, including swales, trenches, tree pits, green roofs, and cisterns, are evaluated with respect to economic, social, environmental, and hydrological performance. Results show that vegetated measures, particularly swales and tree-based systems, achieve the highest overall scores and positive net-benefit values, while predominantly underground systems perform less well. The integrated assessment highlights important co-benefits and trade-offs of blue-green infrastructure and provides decision support for prioritising nature-based solutions in urban rainwater management.