A prototype system to forecast rainfall induced landslides in Italy

We are designing a system to forecast rainfall-induced landslides in Italy. The system is based on a set of rainfall thresholds for the possible initiation of landslides, and an ensemble of small scale landslide hazard and risk zonations. Rainfall thresholds include existing and new, national, regional and local empirical thresholds of the intensity-duration (ID) and normalized-ID types. The new thresholds were calculated using objective methods and robust statistical techniques, exploiting existing and new data on rainfall events that have resulted in landslides. The synoptic landslide hazard zonation was obtained through multivariate statistical analysis of small scale environmental information, and catalogues of historical landslides. Similarly, the risk zonation was prepared exploiting a catalogue of historical landslides with human consequences in Italy. The information obtained from the rainfall thresholds and the hazard and risk zonations is combined in a national-scale warning system for rainfall-induced landslides to support civil defense decisions. tablish if the expected slope failures occur in areas that are considered highly susceptible to landslides, or where landslide risk is severe or significant. 2.2 Rainfall thresholds The set of rainfall thresholds used in the prototype system includes existing (Guzzetti et al. 2007, 2008, and references therein) and new national, regional and local thresholds of the intensity-duration (ID) and normalized-ID types (Fig. 1). Figure 1. Twenty-six rainfall intensity-duration (ID) thresholds for the possible occurrence of landslides in Italy. Very thick lines are national (global) thresholds, thick lines are regional thresholds, thin lines are local thresholds, and dashed lines are thresholds for catastrophic events. Modified after Guzzetti et