COASTAL VULNERABILITY ASSESSMENT OF VENETO BEACHES AND BARRIER ISLANDS, NORTHERN ADRIATIC, ITALY

The assessment of coastal vulnerability to sea storms is critical in coastal management since sea level rise and human pressure affect both the morphological and sedimentary constraints, thus increasing coastal risks. In this work we present an assessment of sea storm vulnerability for the 170 km of coastline of the Veneto area (Northern Adriatic, Italy), using an adaptation of the Coastal Vulnerability Index. The methodology relies on a comprehensive coastal geodatabase and includes the estimate of the Intrinsic Vulnerability (Vi): several variables were analysed and weighted to define the physical and evolutionary conditions of the coast, under the assumption that there is no defence against sea storms. Subsequently, the classification and evaluation of coastal defences (hard and soft) allows the shift from intrinsic to Real vulnerability (Vr). Owing to a methodological adjustment made for the various coastal types (barrier islands or beaches), the results show varying grades of Vi depending on distinct morpho evolutive conditions. Low values of Vi are typical of coastal tracts acting as sedimentary traps in proximity to jettied or unjettied tidal inlets. At the same time, along the Po delta, some barrier islands have dissipative characteristics and positive sedimentary budget due to the sandy load from river branches. In many cases, beaches with moderate Vi benefit from the widespread distribution of hard coastal defences and the presence of coastal dunes, which mitigate vulnerability. Finally, littoral sections with high Vi are mostly afflicted by a persistent sedimentary deficit, resulting in absent or narrow beaches with steep shoreface. Overall, the massive use of hard defence works ensures safety, although impeding any resilience of the morpho sedimentary system.