Planning Nature Based Solutions against urban pluvial flooding in heritage cities: A spatial multi criteria approach for the city of Florence (Italy)

City of Florence, central Italy Aiming at defining a nature-based strategy to mitigate pluvial flood risk, two-tiered methodology is proposed. Firstly, the areas prone are identified by spatial multi-criteria analysis that combines five criteria (imperviousness, slope, hydrologic soil groups, density sewer system and social vulnerability) build Pluvial Flood Index (PFI). The PFI validated comparison with historical events in city it used for identification high priority intervention. Then, this information merged urban planning NBS design constraints identify suitable installation. Results allow definition implementation against flooding identifying each hotspot set measures can be implemented solve problem. proposed approach represents flexible assessment technique reproduced other context provide useful support adoption risk management heritage cities. • A index elaborated combining 5 environmental socioeconomic criteria. hotspots Florence identified. feasibility assessed analyzing constraints. applied contexts.