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Multi-scalar response of an experimental fixed-wall meandering channel to a sediment supply increase

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dc.contributor.authorCortese, David, author
dc.contributor.authorNelson, Peter, advisor
dc.contributor.authorMorrison, Ryan, committee member
dc.contributor.authorWohl, Ellen, committee member
dc.date.accessioned2021-01-11T11:20:21Z
dc.date.available2021-01-11T11:20:21Z
dc.date.issued2020
dc.description.abstractMeandering river planforms are prevalent and well-studied features in the natural landscape. These rivers commonly exhibit a characteristic morphology of fine-grained point bars along the inner banks of meander bends with coarser pools along the outer banks. If subjected to a change in sediment supply, these rivers are likely to respond at various spatial and temporal scales through adjustments to sorting patterns, cross-sectional shape, and reach-scale morphology. In this study, a flume experiment was conducted to document the temporal progression of responses across scales of a fixed-wall meandering channel to a sediment supply increase. The 0.344 m wide experimental channel consisted of four meander bends following a sine-generated trace with a 20-degree crossing angle, meander wavelength of 2.75 m, and a unimodal sediment mixture with median grain size of 0.62 mm. The channel was provided constant flow and sediment supply until an initial equilibrium was established, after which the sediment supply was doubled until a new equilibrium state was reached. The experimental channel developed characteristic bar-pool morphologies and sorting patterns with superimposed, mobile, scaled gravel-dune bed forms during both phases of the experiment. After the sediment supply increase, dynamic adjustments occurring from smaller to larger scales took place. Initially, the dunes essentially disappeared, after which the relief of the bars decreased. Both of these sub-reach-scale responses were temporary, however, and ultimately the dunes and bar-pool morphology returned to their conditions at the beginning of the sediment supply increase. The long-term and largest-scale response to the supply increase was a 44% increase in bed slope. To explain these observations, we propose a conceptual model wherein the channel undergoes a temporal progression of responses from smaller to larger spatial scales, with the total response potential at each scale related to the conditions and constraints at that scale. This conceptual understanding allows us to reconcile seemingly divergent outcomes from previous research on how meandering rivers adjust to sediment supply changes.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.identifierCortese_colostate_0053N_16370.pdf
dc.identifier.urihttps://hdl.handle.net/10217/219557
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2020-
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectflume experiment
dc.subjectgravel-bed river
dc.subjectsediment supply
dc.subjectgeomorphology
dc.subjectchannel response
dc.subjectmeandering river
dc.titleMulti-scalar response of an experimental fixed-wall meandering channel to a sediment supply increase
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineCivil and Environmental Engineering
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)

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