Climate change is increasingly intensifying extreme events in urban areas, including heavy rainfall and flooding as well as heatwaves and droughts. In this context, adaptive and multifunctional stormwater management through blue-green infrastructure (BGI) is gaining importance. This report presents the results of the socio-economic analyses conducted within the research project AMAREX – Adaptation of Stormwater Management to Extreme Events.

The aim of the analysis is to assess stormwater management measures not only in terms of their hydraulic performance and costs but also to systematically capture their additional ecological, social and economic benefits. 

In total, 20 stormwater management measures were analysed, differing in their objectives and design. These include conventional stormwater management measures (RWB), measures optimised for heavy rainfall events (RWB+), and measures with water storage capacity designed to address drought conditions (RWB-N). The analyses draw, among other sources, on hydrological modelling carried out by project partners for two urban pilot areas in Berlin and Cologne.

Methodologically, the report combines three core assessment steps. First, an impact framework was developed to systematically illustrate the direct and indirect effects of stormwater management measures on the water cycle, the environment, urban climate, human health and social aspects. Second, a multi-criteria analysis was applied, integrating ecological, social, economic, water-related and implementation-oriented criteria. Third, selected cost and benefit components were monetised to reflect the overall societal value of the measures within a cost-benefit analysis.

The results demonstrate that measures integrating green elements and water storage capacities deliver particularly high co-benefits. These include positive impacts on urban climate regulation and biodiversity, enhanced recreational and aesthetic value, and improved resilience to heat and drought. By contrast, measures without green components tend to perform significantly worse, especially with regard to social and environmental criteria.

Overall, the report emphasises the importance of integrated and holistic assessment approaches for stormwater management planning. It shows that blue-green infrastructure not only contributes to flood risk reduction, but also plays a crucial role in creating climate-resilient cities with an increased quality of life.