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A debris flow chronology and analysis of controls on debris flow occurrence in the Upper Colorado River valley, Rocky Mountain National Park, CO

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dc.contributor.authorGrimsley, Kyle J., author
dc.contributor.authorRathburn, Sara, advisor
dc.contributor.authorWohl, Ellen, advisor
dc.contributor.authorBledsoe, Brian, committee member
dc.date.accessioned2007-01-03T05:58:38Z
dc.date.available2007-01-03T05:58:38Z
dc.date.issued2012
dc.description.abstractThe role of debris flows along the Upper Colorado River was recently highlighted when the Grand Ditch, a 19th-century water-conveyance ditch, overtopped from snowmelt in 2003 and triggered a large debris flow along Lulu Creek, a tributary of the Colorado. Historical aerial photographs indicate that at least two other debris flows have been triggered from the Grand Ditch over the last century. This study examines the natural regime of debris flows in the Colorado River headwaters to assess whether the Grand Ditch has increased magnitude and frequency of debris flow occurrence on the west side of the Colorado River valley. Ten distinct sites of debris flow deposition were mapped using aerial photographs and field exploration, dated from tree cores and tree scars, and analyzed for magnitude using field-estimated volumes of deposition. Six of these ten depositional sites are on the west side of the valley, and several of them have evidence of multiple debris flows. Forty scarred survivor trees and 38 cores from even-aged stands were dated, with corresponding dates of debris flow occurrence ranging from 1923 to 2003. At least 19 debris flows have occurred in this catchment over the last century, but only those at the across-from-Specimen Creek, Lady Creek, Lulu Creek, and Little Yellow sites appear to have been large enough to affect the Colorado River. There is not a substantial difference in the frequency of total debris flows catalogued at the ten sites of deposition between the east (8) and west (11) sides of the Colorado River valley over the last century, but three of the four largest debris flows originated on the west side of the valley in association with the Grand Ditch, while the fourth is on a steep hillslope of hydrothermally altered rock on the east side of the valley. Although ability to interpret the debris flow record is limited by frequent disturbance and burial of older deposits, and estimates of magnitude have high uncertainty, these data suggest that the Grand Ditch has altered the natural regime of debris flow activity in the Colorado River headwaters by increasing the frequency of debris flows large enough to reach the Colorado River. Likelihood of debris flow occurrence is augmented by steep slopes and hydrothermally altered rock, which are both common in the vicinity of the Grand Ditch. This study demonstrates the applicability of dendrochronology for dating geomorphic events in Rocky Mountain National Park and provides context for restoration following debris flows.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.identifierGrimsley_colostate_0053N_11386_opt.pdf
dc.identifierETDF2012500356GEOS
dc.identifier.urihttp://hdl.handle.net/10217/80348
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relationwwdl
dc.relation.ispartof2000-2019
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.subjectColorado River
dc.subjectRocky Mountain National Park
dc.subjectdebris flows
dc.titleA debris flow chronology and analysis of controls on debris flow occurrence in the Upper Colorado River valley, Rocky Mountain National Park, CO
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.disciplineGeosciences
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)

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