(pubblicato in: Proceedings of the XXIV IUGG General Assembly “EARTH: OUR CHANGING PLANET” Perugia, Italy 2-13 2007)
Majone Ugo, Tomirotti Massimo , Galimberti Giacomo

ABSTRACT:The present paper describes the results of a regional analysis of peak flood flows that has been carried out on the basis of the data recorded in nearly 9000 gauging stations  belonging to different geographical areas of Europe (Italy, Switzerland, Austria, Great Britain, Portugal), North America (USA, Canada), Oceania (Australia) and to other sites of Africa, Asia and South America.

The regionalization procedure is based on the definition of a dimensionless variable Y, obtained by a suitable standardization of the peak discharge, whose probability distribution can be assumed constant for all the considered sites.

The probabilistic model (MG model) obtained by interpolation of the empirical non exceedance frequencies of the maximum values of Y observed at each gauged site gives the probability distribution of peak discharges for return periods ranging from 30-50 years up to about 4000 years. With respect to other probability distributions that are currently used for the same purpose, the MG model provides a better interpolation of the empirical non exceedance frequencies of peak discharges, especially for long return periods.

Keywords: peak flood flows, regional estimation, unpredictable events, maximum probable flood discharge