TXT-tool 2.039-1.3: Topographic and pedological rainfall thresholds for the prediction of shallow landslides in central Italy

Abstract

In Italy, rainfall-induced shallow landslides are frequent phenomena that cause casualties, damages and economic losses every year. At the national and regional scales, empirical rainfall thresholds can predict the occurrence of multiple rainfall-induced shallow landslides. In this work, we updated an historical catalogue listing 553 rainfall events that triggered 723 landslides in the Abruzzo, Marche and Umbria regions, central Italy, between February 2002 and March 2011. For each event, the rainfall duration (D) and the cumulated event rainfall (E) responsible for the failure are known, together with the exact or approximate location of the landslide. Landslides were mapped as single points and were attributed a level of mapping accuracy P, in 3 classes. To analyse the influence of topography and soil characteristics on the occurrence of rainfall-induced shallow landslides, we subdivided the study area in three topographic divisions, and eight soil domains. We analysed the (D, E) rainfall conditions that resulted in the documented shallow landslides in each topographic division and regional soil domain, and we computed ED rainfall thresholds at 5% exceedance probability level for the two subdivisions. We expect that the new topographic and pedological thresholds will contribute to forecast shallow landslides in central Italy, and in areas characterized by similar morphological and soil settings.