Comparative Analysis of Coastal Flooding Vulnerability and Hazard Assessment at National Scale

The evaluation of the coastal hazard and vulnerability caused by storm conditions is an important issue related to coastal flooding and erosion. Although these topics have been widely tackled by past research, they cannot be avoided, but need to be carefully managed by local authorities in order to limit damage to coastal infrastructure, to protect human life, habitats and sensitive species. Usually, this issue is tackled through common approaches at the regional scale. This paper illustrates the first steps of a research project aimed at assessing coastal hazard and vulnerability to wave-induced flooding at the national scale. In order to apply the method to the national scale, it is necessary to select a suitable dataset. This has to be consistent with the whole application area, concerning its spatial distribution, reliability and availability. Thus, one of the aims of this project is to perform a comparative analysis using data available at the national and local scale. The analysis was performed for the area of Montalto di Castro (Tyrrhenian Sea) by using datasets with different spatial resolutions. The results revealed that the use of low resolution data does not significantly affect the estimated nearshore wave features, while the wave runup in underestimated by about 25%. This underestimation influences also the vulnerability and hazard assessments. In particular, the vulnerability is conservatively assessed if low resolution data are used. On the other hand, the hazard is conservatively assessed when low resolution data are used only if the wave runup is amplified by considering the 25% underestimation. The results presented herein can be extended to other sites with the same general features (i.e., microtidal and dissipative coastal stretches).