Steinbakk, Gunnhildur Högnadóttir; Thorarinsdottir, Thordis L.; Reitan, Trond; Schlichting, Lena; Hølleland, Sondre; Engeland, Kolbjørn
Water Resources Research, vol. 52, p. 6897–6915, 2016
American Geophysical Union (AGU)
Statistical ﬂood frequency analysis is commonly performed based on a set of annual maximumdischarge values which are derived from stage measurements via a stage-discharge rating curve model.Such design ﬂood estimation techniques often ignore the uncertainty in the underlying rating curve model.Using data from eight gauging stations in Norway, we investigate the effect of curve and sample uncertain-ty on design ﬂood estimation by combining results from a Bayesian multisegment rating curve model and aBayesian ﬂood frequency analysis. We ﬁnd that sample uncertainty is the main contributor to the designﬂood estimation uncertainty. However, under extrapolation of the rating curve, the uncertainty bounds forboth the rating curve model and the ﬂood frequency analysis are highly skewed and ignoring these featuresmay underestimate the potential risk of ﬂooding. We expect this effect to be even more pronounced in aridand semiarid climates with a higher variability in ﬂoods.