Best- Fit Probability Distribution Model for Peak Flow Data (Rivers of West-Azerbaijan Province, Iran)

Estimating flood return period is important in designing and calculating entrance discharge to the water structures such as dams, canals, bridges and rivers and watershed management. In this study, flood frequency analysis done using data from 30 hydrometric stations in West Azerbaijan province. In this regard, randomness, homogeneity and stationarity of stations tested using Wilcoxon and Mann-Kendall tests and the best-fit probability distribution function selected by chi-square test for each station. Results showed that the log-Pearson type III and log-Normal III distributions performed the best by occupying 70% of the total station number. Using selected distribution functions peak flow of studied stations for different return period estimated. Then results of Calculate the peak flow in the region will be great help in determining dam reservoirs volume.