Frequency distribution models and L-moment characteristics of floods in turkish rivers

In the design of hydraulic structures it is important to determine the amount of a hydrologic variable for a given return period. Therefore the flood frequency analysis is significant in the planning of hydraulic structures. Hosking and Wallis (1993) indicated that determination of an acceptable design criterion depends on the probability distribution and statistical methods which are used to estimate the parameters of the distribution. On the other hand regional analyses provide a generalized evaluation of the information of an event in whole region so that the disabilities arising from the usage of point informations are avoided. Regional informations are applicable to the project areas without any observations or data. Regional frequency analysis based on the method of L-Moments is frequently used in the literature. The L-Moment statistics provide critical information about the regional and point information of floods. In this study, the presence of a parent flood frequency distribution function is investigated both on the basis of watersheds and on the basis of Turkey. Besides L-Moment parameters of maximum flows are studied on point- and regional-scales and the change of the effect of the parameters are investigated on a watershed-scale.