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Un criterio di valutazione delle prestazioni delle funzioni di probabilità applicate alle portate di piena ed alle precipitazioni intense di elevato tempo di ritorno
No full textIn 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)
Modelli probabilistici per la stima delle portate di piena di elevato tempo di ritorno
No full textThe present paper describes the results of a regional analysis of peak flood flows carried out on the basis of the historical series recorded in more than 12000 gauging station distributed across the five continents; the regionalization procedure has been performed by means of suitable standardizations of the peak discharges. If the site-to-site variability of the statistical properties of peak flows is described in terms of the variability of the first two order moments - and therefore of the average and of the coefficient of variation CV - this approach leads to the MG model, introduced by the writers in previous papers. Accounting also for the variability of the third order moment - and therefore of the coefficient of skewness g - a new probabilistic model (generalized MG model) has been obtained. With respect to the other probability distributions considered in the paper, this model provides a better interpolation of the empirical frequency distributions of the peak discharges in the range of high return periods, especially for high values of CV and g. In the same respect, also the original MG model performs better than the probability distributions that are currently used for the analysis of peak flows. Moreover, the peak discharges obtained from the empirical absolute maxima of the standardized variables can be regarded as upper bounds to be used for the design of flood control structures in the presence of particularly high risk level (e.g. dam spillways or embankments to protect nuclear sites)
La ristrutturazione della diga di Mignano
No full textL'articolo presenta lo studio degli scaricatori di superficie relativamente alla ristrutturazione di una grande diga, specificamente la diga di Mignano sul T. Arda (PC). Lo studio rappresenta un esempio significativo di recupero di uno sbarramento esistente attraverso l'utilizzo delle più avanzate conoscenze tecniche e scientifiche3 in campo idrologico, idraulico e di modellistica di laboeratorio
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