Hydraulic Modelling and Historical Inundation Assessment for the Versilia River

Versilia river is located in Italy, in north-east Tuscany. In the nineties, 5 floods occurred in the basin causing a lot of damage also in terms of loss of human lives. The paper begin from the research of the historical floods occurred in the lower river basin starting from the sixteen century up to the tremendous floods that occurred on June 1996. The mathematical analysis of the flow in the floodplain has been carried out by means of 2D unsteady flow mathematical model that implements the complete De Saint Venant equations; this allows to assess the interconnection between historical information and the actual configuration of the river, of the alluvial fan and, above all, accounts for the infrastructures present in the floodplain. Particular stress has been put on the significant changes in the flood flow routing due to urbanisation and construction of the highway and roads. The final goal of the work is to show the usefulness of the historical approach together with a physically based model that can account for the microtopography, the change in the roughness coefficient, and the presence of infrastructures.