Best Fitting Distribution of Daily Stream Flow at Chalus River in Chalusrood Catchment

A comparison of different probability distribution models for describing the daily stream flow in Chalus River is reported. Three stations in catchment were included in the study,each having stable and natural flow records of at least 30 years in length. Time series of discharge flows were derived to categorizedand uncategorized data, in categorized type, data divided to seasonal and monthly classes and then flood frequency analysis was carriedout using 61 distribution functions. In uncategorized method, data examined using distribution functions without any classification.'Easy fit' software was used to fit the most appropriate probability distribution. The study showed that where monthly data wereconsidered, stations tended to be best represented by Burr, Burr 4P,Log Logistic 3P and GEV distribution models, seasonally data were best described by Log Normal distribution model for spring and Burr 4P distribution model for others. For annual series derived we used long duration flow data, Burr 4P model was generally moreapplicable. The study suggests that longer duration do not conform to the same distribution types as short durations, and that catchment properties can influence the type of distribution selected

Keywords:

Chalus River , Frequency Analysis , Probability Distribution , Stream Flow Discharge