Bivariate extreme analysis for coastal flooding in the Adriatic Sea

This study investigates the interaction between storm surge and wave height in the Adriatic Sea, focusing on their combined joint influence on coastal flooding risk under different climate scenarios and return periods. Using bivariate statistical analysis based on measured data (water levels) and hindcast data (significant wave heights), the research quantifies the joint probabilities of extreme storm events and highlights the contribution of waves (wave set-up) in amplifying extreme sea levels (ESLs) in the coastal area. In particular, the study aims to assess extreme sea levels in the Adriatic Sea by providing ESLs maps for different return periods and two IPPC climate change scenarios (SSP1-1.9 and SSP5-8.5). Maximum ESLs are observed in the northern Adriatic, with Venice identified as a hotspot. Wave contributions are shown to substantially double water levels, particularly in the areas between Ancona and Zadar and near the southern entrance at Otranto, emphasizing the need for a bivariate approach to accurately capture these interactions. The projected sea level rise further exacerbates the risks posed by storm events, particularly for vulnerable coastal areas. The present study underscores the need for a more comprehensive understanding of the combined joint effects of storm surge and waves, and enable more effective coastal flooding risk assessments along the Adriatic coast due to extreme sea levels by providing valuable support for designing mitigation measures to address climate-driven extreme events.