Rainfall is the primary trigger of shallow landslides that can cause fatalities, damage to properties and economiclosses in many areas of the world. For this reason, determining the rainfall amount/intensity responsible forlandslide occurrence is important, and may contribute to mitigate the related risk and save lives. Efforts havebeen made in different countries to investigate triggering conditions in order to define landslide-triggering rainfallthresholds. The rainfall thresholds are generally described by a functional relationship of power in terms ofcumulated or intensity event rainfall-duration, whose parameters are estimated empirically from the analysis ofhistorical rainfall events that triggered landslides.The aim of this paper is the derivation of critical rainfall thresholds for landslide occurrence in Sicily, southernItaly, by focusing particularly on the role of the antecedent wet conditions. The creation of the appropriatelandslide-rainfall database likely represents one of main efforts in this type of analysis. For this work, historicallandslide events occurred in Sicily from 1919 to 2001 were selected from the archive of the Sistema Informativosulle Catastrofi Idrogeologiche, developed under the project Aree Vulnerabili Italiane. The correspondingtriggering precipitations were screened from the raingauges network in Sicily, maintained by the Osservatoriodelle Acque - Agenzia Regionale per i Rifiuti e le Acque. In particular, a detailed analysis was carried out toidentify and reconstruct the hourly rainfall events that caused the selected landslides.A bootstrapping statistical technique has been used to determine the uncertainties associated with the thresholdparameters. The rainfall thresholds at different exceedance probability levels, from 1% to 10%, were defined interms of cumulated event rainfall, E, and rainfall duration, D. The role of rainfall prior to the damaging eventswas taken into account by including in the analysis the rainfall fallen 6, 15 and 30 days before each landslide. Theantecedent rainfall turned out to be particularly important in triggering landslides. The rainfall thresholds obtainedfor the Sicily were compared with the regional curves proposed by various authors confirming a good agreementwith these.
|Numero di pagine||1|
|Stato di pubblicazione||Published - 2015|