Modelling storm-induced coastal exposure using hindcast wave data in a densely urbanised coastal area

Abstract Coastal exposure assessment is a crucial prerequisite for reliable coastal risk evaluation and for the implementation of effective prevention and mitigation measures. This paper presents a high-resolution modelling approach for coastal exposure assessment, based on a 43-year wave hindcast dataset, applied to a densely urbanised stretch of coast along the eastern Ligurian Riviera (northwestern Italy). Forty extreme storms from the main directions affecting the Ligurian Sea were simulated through model chains based on a high-resolution digital elevation model (DEM), incorporating both morphological and urban features. Coastal flooding scenarios were derived from the estimation of wave run-up through numerical simulations, and the most appropriate parameter for defining exposure thresholds was selected according to the site-specific morphology and urban configuration. The results show that reliable coastal exposure assessment requires long-term wave datasets and high-quality morphological data, particularly in densely urbanised coastal settings where small variations in wave run-up can lead to abrupt transitions in exposure level. However, they also show that technical approaches alone may not be sufficient, and that effective prevention and mitigation strategies require complementary risk awareness and communication initiatives targeting the local population.