Planning Nature-Based-Solutions through geographic information tools to manage flood risk on Florence city environment

The growth of impervious surfaces due to an exponential and uncontrolled urbanization, the evolution of socioeconomic scenarios and the impacts of climate change have made the urban/peri-urban areas weaker against pluvial-flood risk (e.g. issues related to the correct management of the secondary river network, criticalities associated to culverted or covered rivers). Innovative strategies to make urban/peri-urban environment more resilient and sustainable are needed and Nature Based Solutions (NBS, i.e. actions inspired or supported by nature) can play an important role to provide integrated responses to the environmental, social and economic future challenges. In this context, the aim of the FLORENCE (FLOod risk and water Resources management with Nature based solutions on City Environment) project is to explore the effectiveness of NBS for the flood risk management of the City of Florence (Italy). The project is based on a quantitative evaluation methodology supported by geographic information tools that clarifies the benefits and co-benefits of NBS, highlighting their limitations and exploring the possible synergies with existing infrastructures. First, a GIS based analysis has been made in order to map Ecosystem Services (ES) priority areas, analysing the main ES supply and demand. This analysis is coupled with the identification of the constraints (regulatory, urban planning, economic, environmental, social) to realize a multicriteria zoning of Florence urban environment, highlighting the potential areas for NBS implementation. Lastly, the selection of suitable NBS and their hydraulic modelling is carried out in the identified areas. This allows the evaluation of NBS performances and the identification of the scenarios that best respond to the city's green development needs.