Un criterio di valutazione delle prestazioni delle funzioni di probabilità applicate alle portate di piena ed alle precipitazioni intense di elevato tempo di ritorno

In the present paper a criterion is presented to identify the probability distribution that is more suitable to model the historical series of the annual maxima of peak flood discharges and of rainfall depths for a given duration with special reference to high return period estimates. This method is based on the analysis of a great amount of data referring to peak flows recorded in about 12000 gauging stations distributed across the five continents and to 1 and 24 hour maximum rainfall depths recorded in about 2000 rain gauge stations located in Italy and in the USA. The proposed procedure has been applied to the probability distributions that are currently used for the analysis of the above-mentioned hydrological variables. The results provide useful information in order to select the probability distributions to be used in the formulation of regional models for the estimation of peak discharges or maximum rainfall depths for a given duration corresponding to high return periods (>100 years).