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Record W2072120877 · doi:10.4296/cwrj3204251

Detection of Trends in Low Flows across Canada

2007· article· en· W2072120877 on OpenAlexvenueaboutno aff
Eghbal Ehsanzadeh, Kaz Adamowski

Bibliographic record

VenueCanadian Water Resources Journal / Revue canadienne des ressources hydriques · 2007
Typearticle
Languageen
FieldEnvironmental Science
TopicHydrology and Drought Analysis
Canadian institutionsnot available
Fundersnot available
KeywordsTrend analysisGeographyLow latitudeStructural basinClimatologyLatitudeEnvironmental sciencePhysical geographyGeologyStatisticsMathematics

Abstract

fetched live from OpenAlex

Abstract A study of trends and variability of low flow characteristics was conducted for the Reference Hydrometric Basin Network (RHBN). A seven-day low-flow index from 57 hydrometric stations was extracted and examined to detect trends and changes in the timing of summer and winter seven-day low-flows. A modified Mann-Kendall (MK) nonparametric trend test was applied to the time series at a 0.05 significance level. The variance of the S statistic was modified if the absolute value of serial correlation was significant at a 0.1 significance level. Numerical analysis indicated that northern Canada (stations located above latitude 60oN) experienced an increasing significant trend in seven-day low-flows. A significant downward trend dominated the Atlantic Provinces and southern British Columbia. No evidence of significant trends in the Prairies and eastern Ontario was found. Summer seven-day low-flow shifted to arrive earlier in the year in the Atlantic Provinces and southern Ontario; however, it arrived later in the year in western and northwestern Canada. In 88% of significant trends, winter seven-day low-flow shifted to arrive earlier. Although both winter and summer low flows experienced a shift towards earlier dates in the eastern part of the country, they were in opposite direction in western Canada where winter seven-day low-flows were arriving earlier whereas summer seven-day low-flows were arriving later in the year. Une étude des tendances et de la variabilité de caractéristiques d'écoulements faible a été entreprise pour le réseau hydrométrique de bassin de référence (RHBN). L'index de débit faible de sept jours de 57 stations hydrométriques du commencement de leurs enregistrements à 2003 a été extrait et examiné pour détecter des tendances et changement dans la synchronisation de sept jours d'écoulements faibles de l'été et l'hiver pour différentes et continues longueurs de l'enregistrement. L'essai non paramétrique de tendance de Mann-Kendall (MK) a été appliqué à un niveau de signifiance de 0.05. Afin d'expliquer la corrélation périodique, la variance de la statistique de S a été modifiée quand sa valeur absolue à été significative à un niveau de signifiance de 0.1. L'analyse numérique a indiqué que le Canada nordique (stations situées au-dessus de latitude 60oN) a montré une tendance significative d'augmentation de débit faible de sept jours. Une tendance à la baisse significative a dominé les provinces atlantiques et Colombie Britannique méridionale. Aucune évidence des tendances significatives dans les Prairies et Ontario oriental n'a été trouvée. On a observé que le débit faible de sept jours d'été a été décalé de manière significative pour arriver plus tôt dans les provinces atlantiques et l'Ontario méridional, mais il arrivait plus tard dans l'ouest et du nord-ouest du Canada. Dans 88% de tendances détectées, le débit faible sept- jours d'hiver a été décalé pour arriver plus tôt.Les deux, le débit faible d'été et d'hiver, démontrait un décalage vers des dates plus rapprochées dans la partie orientale du pays. Cependant, du Canada occidental, les tendances en hiver étaient descendantes tandis que les tendances d'été étaient ascendantes.

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How this classification was reachedexpand

Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.002
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesMeta-epidemiology (narrow), Insufficient payload (model declined to judge)
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Not applicable · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.827
Threshold uncertainty score1.000

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0020.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.001
Science and technology studies0.0010.000
Scholarly communication0.0000.000
Open science0.0010.000
Research integrity0.0000.001
Insufficient payload (model declined to judge)0.0010.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.006
GPT teacher head0.201
Teacher spread0.194 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one teacher head, not a consensus.

Study designNot applicable
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations32
Published2007
Admission routes2
Has abstractyes

Explore more

Same venueCanadian Water Resources Journal / Revue canadienne des ressources hydriquesSame topicHydrology and Drought AnalysisFrench-language works237,207