Deterministic and Probabilistic Rainfall Thresholds for Landslide Forecasting

In this paper, authors focus attention on different threshold schemes, which can be adopted when a model is used for landslide forecasting. In some cases they represent the occurrence probability of a landslide, in other cases the exceedance probability of a critical value for an assigned mobility function Y (a function of rainfall heights), indicated as Y-cr, and in further cases they only indicate the exceeding of Y-cr or its prefixed percentages. Clearly, the discussion here reported can be easily extended to the case of flood forecasting models. The empirical model named FLaIR (Forecasting of Landslides Induced by Rainfall, Capparelli and Versace 2011) is used for the study area of Gimigliano municipality (located in Calabria region, southern Italy), characterized by a database with 27 historical landslide events in the period 1940-2011.