Geomorphic processes and risk related to a large landslide dam in a highly urbanized Mediterranean catchment (Genova, Italy)

We present our research on the Prato Casarile landslide dam in Genoa city to illustrate the interactions between slope instability processes and structural stabilization interventions aimed to reduce the hazard in a densely-populated area. Analysis of the degradation of structural interventions constructed after flood events in 1953, 1970 and 2014 contributed to an improved mitigation strategy. At the same time, the slope instability processes intensively advanced, and regressive erosion quickly proceeded to the landslide dam threshold. The discontinuity in human interactions in a geomorphic system, after the initial hazard reduction, resulted in an increased threat that combined with a rise in vulnerability due to urbanization expansion. The research findings underline the necessity of constantly assessing the geomorphic evolution and active processes involved in order to determine the specific actions and interventions required to ensure the stability of the landslide dam. Finally, and more generally, we illustrated that anthropogenic interaction in the geomorphic system, specifically when finalized for hazard mitigation, needs to be continuously performed through both the monitoring and maintenance operation phases of the artificial structures.