Road interruptions due to landslides and floods in Southern Italy

Abstract Road networks in regions exposed to rainfall-induced geo-hydrological hazards are highly vulnerable to service disruptions, yet systematic analyses of road interruption data remain limited. This study addresses this gap by examining road closures caused by landslides and floods along the primary road network of Calabria region (southern Italy), one of the most hazard-prone areas of the country. Using records provided by the national road authority for the period 2016–2024, 241 landslide-induced (RI-L) and 210 flood-induced (RI-F) interruptions were analysed. The results show that RI-L and RI-F occurred with average frequencies of 27 and 23 events per year, respectively, with a pronounced concentration between October and February, consistent with the regional rainfall regime. Approximately one-fifth of Calabria’s municipalities experienced at least one RI-L or RI-F, with clear spatial patterns: RI-L predominantly affected the steep western mountain sectors, whereas RI-F were more frequent along the gentler eastern slopes. Overall, rainfall events linked to both RI-L&F located in the eastern side of the region are characterised by higher cumulated rainfall. Landslides caused more localized, yet longer-lasting closures compared to floods, also because they were triggered by rainfall events more severe than those linked to floods. These findings demonstrate how structured analyses of road interruption chronologies can reveal distinct hazard signatures across different territorial settings and provide useful insights for road managers and territorial authorities, as well as a reproducible framework that can be applied to other regions where comparable data is available.