Best distribution and plotting positions of annual rainfall in the catchment of holy Karbala in Iraq

Abstract EN

The research data analysis of annual rainfall in the Catchment of holy Karbala for the purpose of finding the appropriate frequency distribution of the data.

Seven were applied theory of probability distributions, namely Normal, Log-Normal, Log-Normal Type III, Gamma, Pearson Type III, Log-Pearson Type III and Weibull Type III distributions were investigated as distributions for modeling at-site annual rainfall using several plotting positions formulas at Euphrates river basin in Kerbala.

Frequency curves based on each of these distributions are derived.

Goodness of fit tests, namely Chi-square, Anderson-Darling and Kolmnogorov-Smirnove are applied to fit the theoretical distributions for the observed data.

The study shows that Gamma distribution is one of the best models for annual rainfall in the Catchment of holy Karbala.

The annual rainfall (mm) in the Catchment of holy Karbala, for different return periods (10, 25, 50, 100), were calculated.