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NON‐ZERO LOWER LIMIT IN LOW FLOW FREQUENCY ANALYSIS? 1
Author(s) -
Lawal Semiu A.,
Watt W. Edgar.
Publication year - 1996
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/j.1752-1688.1996.tb03486.x
Subject(s) - skewness , limit (mathematics) , weibull distribution , mathematics , statistics , sampling (signal processing) , flow (mathematics) , series (stratigraphy) , zero (linguistics) , sample (material) , physics , mathematical analysis , thermodynamics , geometry , geology , paleontology , linguistics , philosophy , detector , optics
The implications of fitting distributions with non‐zero lower limits to low flow data are examined. The 3‐parameter Weibull distribution is fitted to annual minimum flow series from 60 long term stations in Canada. The relations between the estimated lower limit and three sampling variables (skewness, smallest, and largest observations) were investigated. The lower limit strongly depends on the sample skewness; it varies directly with the sample skewness, which in turn is highly influenced by the largest observation. For a given skewness, the value of the estimated lower limit is determined by the value of the smallest observation. Therefore, the lower limit cannot be accurately determined, and the resulting low flow estimates will be either too small or too high.