This paper presents some analytical results and numerical illustrations onthe asymptotic properties of flood peak distributions obtained throughderived flood frequency approaches. It confirms and extends the results ofprevious works: i.e. the shape of the flood peak distributions areasymptotically controlled by the rainfall statistical properties, givenlimited and reasonable assumptions concerning the rainfall-runoff process.This result is partial so far: the impact of the rainfall spatial heterogeneity has not beenstudied for instance. From a practical point of view, it provides a general framework foranalysis of the outcomes of previous works based on derived flood frequencyapproaches and leads to some proposals for the estimation of very largereturn-period flood quantiles. This paper, focussed on asymptoticdistribution properties, does not propose any new approach for theextrapolation of flood frequency distribution to estimate intermediate returnperiod flood quantiles. Nevertheless, the large distance between frequentflood peak values and the asymptotic values as well as the simulationsconducted in this paper help quantifying the ill condition of the problem offlood frequency distribution extrapolation: it illustrates how large therange of possibilities for the shapes of flood peak distributions is.
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