Author(s): H. K. Cigizoglu
Linked Author(s):
Keywords: Exceedance probability; Lognormal distribution
Abstract: In this study a method to obtain flow duration curve is presented. In this method the exceedance probability for each flow value is computed repeatedly for all time periods within a year. The applicability of the method to daily mean flows is tested assuming various marginal probability distributions like normal, Pearson type III, log-Pearson type III, 2-parameter lognormal and 3-parameter lognormal distributions. It is seen that the observed flow duration curves were quite well approximated by the 2-parameter lognormal average of probabilities curves. In that case the method requires the computation of the daily mean and standard deviation values of the observed flow data. The method curve enables extrapolation of the available data providing the exceedance probabilities for the flows higher than the observed maximum flow. The method is applied to the missing data problem and the results are quite satisfactory.
Year: 2003