JFET_V12_N4_RP1
Intercomparison of Log Normal and Weibull Distributions for Frequency Analysis of Low-Flows
N. Vivekanandan
Journal on Future Engineering and Technology
2230–7184
12
4
20
26
Chi-square Test, Correlation, Kolmogorov-Smirnov Test, Low-flow, Log-Normal, Mean Square Error, Weibull
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.
May - July 2017
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