IDENTIFICATION AND DELINEATION OF HYDROLOGICAL HOMOGENEOUS REGIONS BY USING L-MOMENT FOR SELECTED BASINS

Abstract

The paper presents results of an application of the L-moments based regional flood frequency analysis to annual maximum peak (AMP) flows observed at five stations (Balikian,Jundian.Manguba,Bekhme and Eski-Kelek) located on the main stream of the Greater Zab River and its tributaries in Iraq. L-moments based regional homogeneity measure (H) showed that the region, defined by five stations, is homogeneous; also, the basin has been sub-divided into four homogeneous regions using Ward’s clustering method based on the site characteristics only. The results of various goodness-of-fit measures (L-moment ratio diagram, average weighted distance and Z ^DIST measures) showed that region under study has three candidates: gamma (GAM), exponential (EXP) and weibull (WEB) as regional distribution. Based on the results of different accuracy measures mentioned before a dimensionless flow duration curve (DFDC) was obtained by averaging the standardized empirical flow duration curve of all gauging stations.The multiple regression equation. was obtained and used to estimate the index flow for Bekhme station and finally the flow duration curve of this station was estimated by multiplying the dimensionless regional flow duration curve by the estimated of index flow.