Optimum Frequency Distributions of Rainfall Erosivity Factor in Iran

Document Type : Complete scientific research article

Authors

Tarbiat Modares University

Abstract

Evaluation of frequency distributions for rainfall erosivity factor analysis has been less considered. Thus, the present study aimed to identify and evaluate different frequency distributions fitted to the amount of rainfall erosivity factor in monthly, seasonal and annual scales in Iran. For this attempt, entire available rainfall events reported for 20 years in 70 stations were analyzed based on the Wischmeier and Smith equation. The different frequency distributions were then fitted to data in each of the time scale and station using EasyFit software with the help of chi-square test. According to results maximum Gumble distribution was selected as the best fitted distribution in most of months and seasons and also, 3-parameter lognormal, gamma and 2-parameter lognormal frequency distributions stood in the first rank among fitted frequency distributions. Also, stations with more stable rainfall regime and influenced by similar rainfall regimes had less variability in the type of fitted distributions in different time scales.

Keywords

References

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Journal of Water and Soil Conservation
Volume 23, Issue 1
May 2016
Pages 301-306

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