Gabriele Salvatore, Arnell Nigel, 1991, A hierarchical approach to regional flood frequency analysis, Water resources research 27 (1991): 1281–1289.,
URL: http://www.cnr.it/prodotto/i/277265

A hierarchical approach to regional flood frequency estimation is described, where higher-order parameters controlling the skewness of annual maximum floods are determined from larger regions than are used for determining parameters controlling the coefficient of variation. Procedures based on two-component extreme value and generalized extreme value distributions are developed, and it is shown that dividing a region into subregions to estimate some parameters can lead to more precise quantile estimates. The practical problem of defining the optimum number of subregions is discussed.

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