An approach for flood hazard modelling and mapping in the medium Valtellina

In Lombardy Region, as in many other contexts all over the world, hazard maps does not have a precise legislative confirmation. Despite this, they are necessary to support several institutional activities, among which local urban planning. An approach has been presented of hazard analysis and mapping that fits the Lombardy Region legislative framework, but introduces a level of experimental modelling, making use of SOBEK 1D-2D as a tool for hydrodynamic simulations. A stretch of 17 km of the Adda river in Valtellina has been modelled, referring to twelve scenarios characterised by different temporal probabilities, and comprising the main sources of uncertainty. Result were compared with available local hydraulic studies, and combined to obtain two complementary flood hazard maps which could usefully support urban planning. Advantages and drawbacks of this modelling approach, together with considerations related to flood hazard mapping are discussed.