Theme-2-5-Uncertainties in probabilistic modelling of floods.

Abstract

The paper discusses the various components of hydrologic and hydraulic uncertainties that combinedly constitute the hydraulic risk of a water resources structure; and specifically examines in detail model and parameter uncertainties inherent in generally used statistical extrapolation procedures for estimation of extreme flood magnitudes for different design frequencies. The study illustrates the use of moment-ratio diagram, wherein coverage areas/points of distributions commonly used for analysis of hydrologic data are shown, for reducing model uncertainty. Further, the paper presents a procedure, which can potentially reduce parameter uncertainty of the identified model by developing generalised values of the parameters through the use of a weighting between sample and regional parameter estimates. A numerical example, reported in the paper, illustrates the general applicability of the procedures detailed.