Stochastic analysis of long dry spells in Calabria (Southern Italy)

A deficit in precipitation may impact greatly on soilmoisture, snowpack, streamflow, groundwater and reservoirstorage. Among the several approaches available to investigatethis phenomenon, one of the most applied is the analysisof dry spells. In this study, a non-homogeneous Poisson modelhas been applied to a set of high-quality daily rainfall series,recorded in southern Italy (Calabria region) during the period1981–2010, for the stochastic analysis of dry spells. Firstly,some statistical details of the Poisson models were presented.Then, the proposed model has been applied to the analysis oflong dry spells. In particular, a Monte Carlo technique wasperformed to reproduce the characteristics of the process. As aresult, the main characteristics of the long dry spells haveshown patterns clearly related to some geographical featuresof the study area, such as elevation and latitude. The resultsobtained from the stochastic modelling of the long dry spellsproved that the proposed model is useful for the probabilityevaluation of drought, thus improving environmental planningand management.