Use of Gamma Distribution in Hydrological Analysis

Authors: HAFZULLAH AKSOY

Abstract: In this study, amounts of daily rainfall and the ascension curve of the hydrograph are investigated. In both cases, the 2-parameter gamma distribution is used. The distribution is fitted to the amounts of daily rainfall and to the differences between the flows of successive days on the ascension curve of the hydrograph. The shape and scale parameters of the distribution, in both cases, are estimated in a monthly time interval. A 30-year daily rainfall series and a 35-year daily runoff series are used for the application. It may be seen that the distribution fits very well to the rainfall data and also that the ascension curve of the hydrograph can easily be represented by the distribution.

Keywords: Gamma distribution, daily rainfall, daily runoff, hydrograph, ascension curve.

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