Regional flood frequency analysis forÇoruhBasin ofTurkey withL‐moments approach

In this paper, a regional flood frequency analysis of Ç oruh Basin was performed with the L ‐moments method. Because the area of Ç oruh Basin is large (21 100 km 2 ), and the climatic, hydrologic, and topographic characteristics vary throughout the basin, it was divided into four sub‐regions for examination. Discordancy measure tests were performed for the sites located in each sub‐region. The H heterogeneity test was carried out by performing 500 simulations with the K appa probability distribution for the homogeneity of the region. With the help of a diagram of the L ‐moment ratios and by administering the Z goodness‐of‐fit measure test, the appropriate distribution was determined for each sub‐region. The distributions were used to identify the quintiles according to various probabilities of non‐exceedance. The accuracies of the estimated measured for the regional growth curves and quantiles were calculated using M onte C arlo simulation. Finally, the flow values determined from the quantiles estimated with the L ‐moments method were compared with those estimated previously with an at‐site frequency analysis ( G umbel distribution) on the basin master plan for four large dams in the Ç oruh B asin.