Integrating risk and feasibility in the spatial planning of nature-based solutions: a cross-city analysis of Barcelona, Boston, and Rotterdam

Abstract Urban areas increasingly turn to nature-based solutions (NbS) to adapt to climate-related risks, which require integrated and systemic planning evaluating risks and feasibility of implementation. Here we develop a transferable, SETS-based decision-support framework that spatially analyzes multi-hazard climate risk and feasibility for four NbS types: green roofs, permeable pavements, rain gardens, and urban parks, across Barcelona, Boston, and Rotterdam. Integrating spatial and statistical analyses, we identify where different kinds of NbS are both most needed and most feasible for mitigating urban flooding and heat stress. Results reveal strong spatial clustering of risks and feasibility across all cities, with heat risk showing the highest spatial autocorrelation. Across cases, green roofs and permeable pavements consistently exhibit high feasibility in dense, heat-prone urban areas, whereas rain gardens and urban parks are constrained by land availability and underground infrastructure. The comparative analysis highlights how urban morphology, governance structures, and socio-economic factors shape feasibility for NbS implementation. Overlaying risk and feasibility identifies priority high risk –high feasibility zones for rapid implementation and flags high-risk/low-feasibility neighborhoods where infrastructure deficits and vulnerability may constrain adaptation, supporting more justice-oriented, context-sensitive NbS planning.