Coastal vulnerability assessment and challenges for nature - based solutions (coastal dunes) in the Northern Adriatic sea

As sea level rise and human activities increasingly affect both morphological and sedimentary dynamics, coastal risks are becoming more severe. As a result, assessing coastal vulnerability to storm events and identifying innovative, resilient, nature-based solutions to combat erosion have become essential components of modern coastal management strategies. This study presents an integrated assessment approach applied to 140 km of sandy coastline in the Northern Adriatic Sea (Italy), an area characterized by varying degrees of anthropogenic impact. An adapted version of the Coastal Vulnerability Index was employed to estimate the Potential Vulnerability (Vp), which reflects the morpho-evolutionary conditions of individual coastal cells under the assumption of no protective measures against sea storms. The subsequent classification and evaluation of both hard and soft coastal defences — including natural features such as dunes— enable the transition from Potential to Real Vulnerability (Vr). To more specifically assess the presence, functionality, and development potential of coastal dunes, the analysis incorporates two complementary dune indicators: ISand, which measures the system’s potential for aeolian-driven transport of beach sediment towards the dune, and IDune, which evaluates the current eco-morphodynamic condition of the existing dune systems.