Developing a framework for the assessment of current and future flood risk in Venice, Italy

Abstract. Flooding has been a serious struggle to the old-town of Venice, its residents and cultural heritage and continues to be a challenge in the future. Despite this existence-defining condition, limited scientific knowledge of flood hazard and flood damage modelling of the old-town of Venice is available to support decisions to mitigate existing and future flood risk. Therefore, this study proposes a risk assessment framework to provide a methodical and flexible instrument for decision-making for flood risk management in Venice. It uses a state-of-the-art hydrodynamic urban model to identify the hazard characteristics inside the city of Venice. Exposure, vulnerability, and corresponding damages are modelled by a multi-parametric, micro-scale damage model which is adapted to the specific context of Venice with its dense urban structure and high risk awareness. A set of individual protection scenarios is implemented to account for possible variability of flood preparedness of the residents. The developed risk assessment framework was tested for the flood event of 12 November 2019. It was able to reproduce flood characteristics and resulting damages well. A scenario analysis based on a meteorological event like 12 November 2019 was conducted to derive flood damage estimates for the year 2060 for a set of sea level rise scenarios in combination with a (partially) functioning storm surge barrier MOSE. The analysis suggests that a functioning MOSE barrier could prevent flood damages for the considered storm event and sea level scenarios almost entirely. It could reduce the damages by up to 34 % for optimistic sea level rise prognoses. However, damages could be 10 % to 600 % times higher in 2060 compared to 2019 for a partial closure of the storm surge barrier, depending on different levels of individual protection.