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Dam removals and downstream bar-pool morphology

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dc.contributor.advisor Lancaster, Stephen T.
dc.creator Zunka, John Page Purnell
dc.date.accessioned 2011-06-20T22:20:27Z
dc.date.available 2011-06-20T22:20:27Z
dc.date.copyright 2011-06-06
dc.date.issued 2011-06-20
dc.identifier.uri http://hdl.handle.net/1957/21821
dc.description Graduation date: 2012 en_US
dc.description.abstract Bar-pool morphology in rivers can provide vital habitat to aquatic species, notably salmonids, which require gravel riffles to bury eggs and pools for hydraulic and cold-water refuge. In some cases, the erosion and subsequent deposition of coarse sediment downstream of a dam removal can modify habitat by inundating bar-pool structure, filling pools, and homogenizing the channel bed. To assess extents and durations of geomorphic impacts of dam removals, project managers may devote significant resources to detailed one-dimensional numerical modeling studies and requisite data collection, but the manner in which these width-averaged sediment inundation depths are expressed laterally and interact with pre-existing morphology is not considered. We address the uncertainty associated with the lateral impacts of sediment pulses by presenting and evaluating a conceptual framework for both visualizing dam removal data and explicating hypotheses describing the response of cross-channel bed relief to changing sediment thicknesses. Within this conceptual framework, we examine, using data from two dam removals in Oregon, the hypothesis whereby bed relief in a cross-section is formed and initially increased by sediment deposition and subsequently diminished during continued deposition. Results suggest that the conceptual framework is a useful means for visualizing dam removal data and effectively captured the different behaviors and changing morphologies observed in the cross-sectional data at each field site. Although there was some data that the hypothesis did not describe sufficiently, the confirmation of the general trends of the hypothesis in much of the data make it a good starting point for estimating the range of responses to dam removal of alluvial channels that exhibit bar-pool morphology and developing more physically detailed and site specific hypotheses. en_US
dc.language.iso en_US en_US
dc.relation Oregon Explorer en_US
dc.subject Dams en_US
dc.subject Rivers en_US
dc.subject Sediment en_US
dc.subject Morphology en_US
dc.subject.lcsh Dam retirement -- Oregon -- Calapooia River en_US
dc.subject.lcsh Dam retirement -- Oregon -- Sandy River en_US
dc.subject.lcsh River sediments -- Oregon -- Calapooia River en_US
dc.subject.lcsh River sediments -- Oregon -- Sandy River en_US
dc.subject.lcsh Bars (Geomorphology) -- Oregon -- Calapooia River
dc.subject.lcsh Bars (Geomorphology) -- Oregon -- Sandy River
dc.title Dam removals and downstream bar-pool morphology en_US
dc.type Thesis/Dissertation en_US
dc.degree.name Master of Science (M.S.) in Water Resources Engineering en_US
dc.degree.level Master's en_US
dc.degree.discipline Science en_US
dc.degree.grantor Oregon State University en_US
dc.contributor.committeemember Tullos, Desiree
dc.contributor.committeemember Meigs, Andrew
dc.contributor.committeemember Grant, Gordon
dc.contributor.committeemember Egbert, Gary


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