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Practical aspects of low‐flow frequency analysis
Author(s) -
Nathan R. J.,
McMahon T. A.
Publication year - 1990
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr026i009p02135
Subject(s) - weibull distribution , quantile , statistics , mathematics , maximum likelihood , method of moments (probability theory) , flow (mathematics) , probability distribution , estimation , frequency distribution , frequency , selection (genetic algorithm) , distribution (mathematics) , computer science , mathematical analysis , engineering , geometry , systems engineering , estimator , artificial intelligence
This paper considers some practical aspects concerning the application of the Weibull distribution to low‐flow frequency analysis. Two‐ and three‐parameter forms of the distribution are fitted to a total of 987 distributions derived from the daily flow data of 134 catchments located in southeastern Australia. The relative performance of three estimation methods (moments, maximum likelihood, and probability weighted moments) is investigated, and it is found that the different estimation methods provide distinct sets of quantile estimates. The method of probability weighted moments is more likely to give unsatisfactory estimates of the smallest drought and in general tends to yield less severe estimates of drought volumes relative to the other two methods. The method of maximum likelihood, however, occasionally provides estimates of drought volumes that are many times greater than that yielded by the methods moments or probability weighted moments. In addition, the differences between low‐flow frequency estimates based on calendar and hydrologic years is investigated, and recommendations are given for the selection of an appropriate subset of the data to be fitted.