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Treatment of Zeroes in Tail Modeling of Low Flows.

Durrans, S. Rocky, Ouarda, Taha B. M. J., Rasmussen, Peter F. et Bobée, Bernard (1999). Treatment of Zeroes in Tail Modeling of Low Flows. Journal of Hydrologic Engineering , vol. 4 , nº 1. p. 19-27. DOI: 10.1061/(ASCE)1084-0699(1999)4:1(19).

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Résumé

The presence of zeroes in a record of low flows usually has been interpreted as being indicative of a stream that goes dry during some periods. However, in some instances, zeroes may appear in a gauging record simply because the actual discharge was below a measurement threshold. For example, in some regions it is sometimes true that the lower limit of a stream gauge is above the true stream bottom, and any (censored) discharges not registered by the gauges are recorded as zeroes. This paper presents a comparison of alternative methods for treatment of zeroes in low-flow estimation procedures when tail models are employed for modeling purposes. Simulation experiments indicate that a Weibull tail model, as fitted using a likelihood-based method for inclusion of censored data, is the best estimator of the 10-year low-flow quantile when zeroes in a data set have arisen as a consequence of censoring. When zeroes in a data set exist because the stream is an ephemeral one, a lognormal mixed tail model fitted using maximum likelihood is the best performer. When one is not sure whether zeroes in a data set are real, it is recommended that the 10-year low-flow quantile be estimated by treating the zeroes as censored values and performing the estimation using the Weibull tail model fitted using maximum likelihood.

Type de document: Article
Mots-clés libres: water discharge measurement; hydrologic data; water discharge; stream gauge; comparative studies; river and stream beds; rivers and streams; low flow
Centre: Centre Eau Terre Environnement
Date de dépôt: 03 févr. 2021 19:42
Dernière modification: 03 févr. 2021 19:42
URI: https://espace.inrs.ca/id/eprint/11142

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