Assessing Potential Effects of Climate Change on Rainfall-Induced Shallow Landslides in the Peloritani Mountains Area, Sicily

Climate change due to atmospheric greenhouse gas emissions may cause significant modifications to precipitation and other meteorological processes, with potential consequences on the frequency of occurrence of shallow landslides. This study aims at investigating the potential effects of climate-change induced rainfall modifications on the future occurrence of rainfall-induced shallow landslides, based on the analysis of RCM projections and hydrologic and slope stability simulations. Changes in precipitation are assessed by comparing future RCM-simulated rainfall series with hindcasts valid for the historical baseline (assumed as 1961–1990), and by considering the two emission scenarios RCP4.5 (intermediate) and RCP8.5 (high-emissions). The estimated changes enable to adjust the parameters of a stochastic rainfall model, used as input to carry out Monte Carlo simulations allowing to estimate the probability of landslide triggering for future periods. The method is applied to the Peloritani mountains area in Sicily (Italy), which has been hit several times by diffused shallow landslides in the past decade. The obtained results prevalently indicate a future decrease of the probability of landslide triggering, directly connected with climate-change induced increase of the inter-arrival times of rainfall events. Outcomes of the study also evidence the importance of assessing RCM data uncertainty, given that different climate-projection data may provide opposite indications.