Hydrological and Paleo-Drought Variability in the Winnipeg River Basin, Canada and the Canadian Prairies

Persistent Link:
http://hdl.handle.net/10150/194832
Title:
Hydrological and Paleo-Drought Variability in the Winnipeg River Basin, Canada and the Canadian Prairies
Author:
St. George, Scott
Issue Date:
2007
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Changing hydroclimatic conditions are the primary source of risk to hydroelectric power generation. The research described in this dissertation investigates hydrological and drought variability in the Winnipeg River basin, Canada, during the last several hundred years using instrumental hydroclimate data and paleoclimatic records derived from tree rings. The basin drains parts of northwestern Ontario, northern Minnesota and southeastern Manitoba, and is the most important component of the hydrological system used to generate power in Manitoba. Extreme low annual flows in the Winnipeg River are associated with enhanced meridional flow across western Canada during summer and autumn, which suppresses precipitation over the watershed and reduces runoff from spring snowmelt. In contrast to the declining flows observed for other regional rivers, mean annual discharge in the Winnipeg River basin has increased substantially since the early 1920s. For a longer perspective, fifty-four ringwidth chronologies (mainly Pinus resinosa and P. strobus) were used to assess changes in summer climate in the Winnipeg River region since AD 1783. Tree growth in this region is significantly, but weakly, correlated with both temperature and precipitation during summer. Synthetic tree-ring records produced by the Vaganov-Shashkin model of tree-ring formation are consistent with these relationships with climate, and suggest that the primary factor limiting tree growth switches from temperature to moisture in mid-summer. The Winnipeg River tree-ring record indicates that summer droughts were more persistent in the 19th and late 18th century than during the last 100 years, but there is no evidence that drought was more extreme prior to the onset of direct monitoring.This dissertation also examines past changes in summer drought over the broader region using 138 ringwidth records from the Canadian Prairies provinces and adjacent areas. Regional ringwidth signals are primarily related to summer moisture and drought conditions. These summer-sensitive records are not linearly related to major modes of climate variability, including ENSO and the PDO, which mainly affect the climate of western Canada during winter. Extended drought records inferred from regional tree-ring series indicate that drought on the Canadian Prairies has exhibited considerable spatial heterogeneity over the last several centuries.
Type:
text; Electronic Dissertation
Keywords:
Canada; Winnipeg River; Dendrochronology; Tree Rings; Drought; Canadian Praires
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Evans, Michael N.
Committee Chair:
Evans, Michael N.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleHydrological and Paleo-Drought Variability in the Winnipeg River Basin, Canada and the Canadian Prairiesen_US
dc.creatorSt. George, Scotten_US
dc.contributor.authorSt. George, Scotten_US
dc.date.issued2007en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractChanging hydroclimatic conditions are the primary source of risk to hydroelectric power generation. The research described in this dissertation investigates hydrological and drought variability in the Winnipeg River basin, Canada, during the last several hundred years using instrumental hydroclimate data and paleoclimatic records derived from tree rings. The basin drains parts of northwestern Ontario, northern Minnesota and southeastern Manitoba, and is the most important component of the hydrological system used to generate power in Manitoba. Extreme low annual flows in the Winnipeg River are associated with enhanced meridional flow across western Canada during summer and autumn, which suppresses precipitation over the watershed and reduces runoff from spring snowmelt. In contrast to the declining flows observed for other regional rivers, mean annual discharge in the Winnipeg River basin has increased substantially since the early 1920s. For a longer perspective, fifty-four ringwidth chronologies (mainly Pinus resinosa and P. strobus) were used to assess changes in summer climate in the Winnipeg River region since AD 1783. Tree growth in this region is significantly, but weakly, correlated with both temperature and precipitation during summer. Synthetic tree-ring records produced by the Vaganov-Shashkin model of tree-ring formation are consistent with these relationships with climate, and suggest that the primary factor limiting tree growth switches from temperature to moisture in mid-summer. The Winnipeg River tree-ring record indicates that summer droughts were more persistent in the 19th and late 18th century than during the last 100 years, but there is no evidence that drought was more extreme prior to the onset of direct monitoring.This dissertation also examines past changes in summer drought over the broader region using 138 ringwidth records from the Canadian Prairies provinces and adjacent areas. Regional ringwidth signals are primarily related to summer moisture and drought conditions. These summer-sensitive records are not linearly related to major modes of climate variability, including ENSO and the PDO, which mainly affect the climate of western Canada during winter. Extended drought records inferred from regional tree-ring series indicate that drought on the Canadian Prairies has exhibited considerable spatial heterogeneity over the last several centuries.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectCanadaen_US
dc.subjectWinnipeg Riveren_US
dc.subjectDendrochronologyen_US
dc.subjectTree Ringsen_US
dc.subjectDroughten_US
dc.subjectCanadian Prairesen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorEvans, Michael N.en_US
dc.contributor.chairEvans, Michael N.en_US
dc.contributor.committeememberMeko, Daviden_US
dc.contributor.committeememberBetancourt, Julioen_US
dc.contributor.committeememberOverpeck, Jonathanen_US
dc.contributor.committeememberHirshboeck, Katherineen_US
dc.identifier.proquest2417en_US
dc.identifier.oclc659748320en_US
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