ROBUST SIMPLE SCALING ANALYSIS OF FLOOD PEAKS SERIES

Simple scaling theory explains the spatial variability of peak flow pr ocesses by their indexation on a set of scale parameters, such as the size of drainage basins. On this basis, a regional analysis can be con ducted to construct a unique growth curve. However, a drawback of the simple scaling approach is that it assumes that the coefficients of Va riation of peak flow distributions are identical throughout a region. Although empirical data might display statistical properties which cor respond to simple scaling assumptions, the coefficient of variation of flood peaks depends on drainage area. We discuss this fact here and w e suggest using the empirical Bayes method to take into account this r egional variation of the coefficient of variation. The advantage of us ing an empirical Bayes analysis subsequent to simple scaling modeling is illustrated using a set of 109 flood series from the Province of On tario, Canada.