Parent Flood Frequency Distribution of Turkish Rivers

摘要

This study investigates the existence of a single parent flood frequency distribution on a Turkish scale. In the design of hydraulic structures, estimating the project flood of a given period or probability is usually the first step. Determining an acceptable design criterion depends substantially on the probability distribution of floods. In this study, annual peak series from 268 Turkish rivers was collected and a database of L-Moment ratios was constructed. The best-fit probability distribution (PD) model was investigated among seven distribution models (generalized logistic, GLO, generalized extreme value, GEV, generalized Pareto, GPA, three-parameter lognormal, LN3, Pearson type 3, P3, Gumbel, GUM, and normal distribution, N) by using a framework of L-moment ratio diagrams. The L-Moment ratio framework used in this study consisted of two sequential procedures. The first graphical procedure evaluated the L-Moment diagrams visually while the second procedure is based on the hypothetical testing procedure of L-Moment diagrams. The results of a graphical inspection of the dataset show GEV distribution as a potential parent PD of the floods in Turkey. A more detailed hypothetical testing procedure comprises Monte Carlo simulations produced from a GEV model. In a hypothetical testing procedure the variability of L-skewness and L-kurtosis values of sample data are situated within the theoretical limits of GEV distribution. Consequently, the GEV distribution is accepted as a single parent PD for annual maximum flow series of Turkey.