GreenStorm targets nature-based solutions designed to manage stormwater (NBSsw) as a means of urban transition, with a specific focus on climate adaptation, resilience of urban vegetation, but also enhanced social benefits. The hydrologic and thermal performance of NBSsw during present and future climate extremes (high intensity rainfall, drought, heat waves, frost/thaw) will be assessed for a range of NBSsw structures and a wide span of European climates, by coupled monitoring / modeling. Improved NBSsw structures, and pathways for their acceptable implementation in urban areas will be developed based on cocreation workshops with all relevant stakeholders (professionals and citizens). A real case study in Copenhagen will serve to demonstrate NBS implementation in a community engaged approach and, based on a cross analysis with data and feedback from Paris, Athens, Genoa and Östersund, allow to identify drivers for NBSsw upscaling. Based on these results, potentials for widespread implementation of NBSsw at urban catchment scale will be analysed in the 5 partner countries (France, Denmark, Sweden, Greece, Italy) and the hydrologic/hydraulic and thermal benefits modelled.