Future Urban Setting and Effects on the Hydrographic System. The Case Study of Bologna, Italy

Urban planning should include the natural features of the territory such as its geology, geomorphology, and urban settlements, but this only happens marginally. Hydrogeological risk affects 31% of the Italian territory, and extreme events are increasingly frequent. They put in crisis the systems of sewerage systems or that generate the flooding of waterways. For these reasons, it is important to study the role of natural infrastructure in flood hazards and the service of sediment retention in a catchment. The study area is the portion of the water catchment area of the Reno River, which collects water from the Tuscan-Emilian Apennines, upstream of the metropolitan area of the city of Bologna. The choice of the study area is linked to the extreme meteoric event that occurred in September 2021, which put in crisis the sewerage network of Bologna city and caused severe hardship to the population and strategic structures. The analyses concern two ecosystem services: urban flood risk mitigation and overland sediment generation and delivery. Specifically, using InVEST (IntegratedValuation of Ecosystem Services and Tradeoffs) software, it is assessed how the full implementation of the municipal planning forecasts can affect the provision of these services. Local planning transposes the overarching constraint planning, but it is essentially adding the knowledge of the ecosystem services that are usually neglected in the definition of plan strategies. The inclusion of ecosystem services, in addition to contributing to a holistic vision, guarantees a more resilient territory, especially concerning the growing threats related to climate change.