Volume 12 Issue 4 May - July 2017
Research Paper
Intercomparison
of Log Normal and Weibull Distributions for Frequency Analysis
N. Vivekanandan*
Scientist-B,
Central Water and Power Research Station, Pune, Maharashtra, India.
Vivekanadan,N.
(2017). Intercomparison of Log Normal and Weibull Distributions for Frequency
Analysis. i-manager’s Journal on Future
Engineering and Technology, 12(4), 20-26. https://doi.org/10.26634/jfet.12.4.13628
Abstract
Quantitative
information on the low-flows regime of a stream is of utmost importance while
making decisions on varied water resources management issues. The paper details
a study on estimation of low-flows using 2-parameter Log- Normal (LN2) and
Weibull (WB2) distributions for river Periyar at Neeleswaram site. The maximum
likelihood method is used for determination of parameters of the distributions.
Goodness-of-Fit (GoF) tests, viz., Chi-square and Kolmogorov- Smirnov are used
for checking the adequacy of fitting of LN2 and WB2 distributions to the series
of annual minimum d-day average flows for different durations of 'd', such as
7-, 10-, 14-, and 30-days. Model Performance Indicators, viz., correlation
coefficient and root mean square error is used to evaluate the performance of
the probability distributions adopted in frequency analysis of low-flows with a
specific objective to identify the best suitable distribution amongst LN2 and
WB2 studied for estimation of low-flows. The GoF test results and values of
MPIs indicate the WB2 is better suited distribution for estimation of low-flows
at Neeleswaram site. Low-flow frequency curves using LN2 and WB2 distributions
are developed and presented in the paper.
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