Stima con modelli idrologici del rischio idraulico del Rio Torriane

The flooding of a watercourse is one of the major environmental risks linked to human activities, with consequences on the safety of the population and economic losses due to the interruption of services. It is therefore necessary to define intervention strategies for the hydraulic protection of areas potentially subject to flooding. There is a clear need for increasingly detailed analyses of these phenomena, to foresee and define the most exposed areas and design defense works, by evaluating case by case the best solution between structural and non-structural interventions. This study, carried out in collaboration with the Consorzio delle Bonifica Renana, aims to analyze the hydraulic functioning of the Torriane River, a hilly watercourse that is a left tributary of the Savena torrent in the municipality of Bologna. The hydrographic left of the Torriane River is partly occupied by a public road system subject to periodic overflows during the most intense rainfall events. Using the rational method, the flood flows are defined, relative to return period, of 2, 30 and 200 years. Flood flows are evaluated basing on the local rainfall regime and the characteristics of the basin. The calculation protocol related to the study of the rainfall regime is established by the competent basin authority, which publishes the regionalization models of rainfall and flow rates relative to the various regional basins. The geometric features of the Torriane basin and its sub-basins were defined through a detailed analysis. Once the flood flows were defined, the estimation of the extent of the floodable areas was carried out using the Hec-Ras software. In order to design the hydraulic works of the basin, aimed at preventing new floods, preliminary survey and in situ investigation activities have been developed. The reshaping of the riverbed and the creation of a retaining wall to support the road system are proposed solutions to reduce the risk of flooding in critical sections.