Regional analysis of superficial slope instability risk in Calabria (Italy) through a pluviometrical approach

alabria region does not present relevant homogeneity for what regards the number and the characteristics of the pluviometrical events affecting it. Using about 200 historical series of daily rainfalls, for which at least 15 years of observations are available., an investigation has been carried out to point out the spatial distribution of rainfall events number and magnitudes. The applications relative to this approach, called POT (Peak Over Threshold) or PDS (Partial Duration Series), examine the generic historical series constituting the whole stochastic process. First, the maximum intensity has been assumed as the magnitude of the generic event, then other factors such as total rain and average intensity of the event itself have been assumed too. The analysis has been carried out on events exceeding, in some prefixed threshold, conditions for what regards the above-mentioned factor. Definitively, the events of the past presenting peculiar characteristics over variable threshold values have been calculated and analysed. The description of the spatial variability of the number and magnitude of pluviometrical events exceeding threshold values is proposed through maps traced with the "Kriging" method. The methodology we used permits to delineate the areas of the regional territory affected by major pluviometrical risk for what regards shallow slope instabilities; moreover the periods during the year in which the events, relative to exceeding threshold values, are more frequent have been pointed out.