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dc.contributor.authorCoe, Jeffrey A.
dc.contributor.authorBessette-Kirton, Erin K.
dc.contributor.authorSlaughter, Stephen L.
dc.contributor.authorRengers, Francis K.
dc.contributor.authorContreras, Trevor A.
dc.contributor.authorMickelson, Katherine A.
dc.contributor.authorTaylor, Emily M.
dc.contributor.authorKean, Jason W.
dc.contributor.authorJacobacci, Kara E.
dc.contributor.authorHanson, Molly A.
dc.date.accessioned2019-08-13T18:59:22Z
dc.date.accessioned2022-02-02T14:38:56Z
dc.date.available2019-08-13T18:59:22Z
dc.date.available2022-02-02T14:38:56Z
dc.date.issued2019
dc.identifier.urihttps://hdl.handle.net/11124/173164
dc.identifier.urihttp://dx.doi.org/10.25676/11124/173164
dc.description.abstractLong-term records of the magnitude and frequency of debris flows on fans are rare, but such records provide critical information needed for debris-flow hazard and risk assessments. This study explores the history of debris flows on a fan with seasonally inhabited cabins at Pope Creek along the Entiat River about 48 km upstream from the town of Entiat, Washington. Motivation for this study was provided by the Duncan Fire, a wildfire which burned the Pope Creek basin in 2014 and resulted in debris flows and water-dominated floods on the fan between August 2014 and October 2016. We excavated and mapped seven 6-m long (2.4- m deep) trenches, mapped deposits on the surface of the fan, and constrained the ages of deposits using radiocarbon dating and the computer program OxCal. Preliminary results indicate that there have been at least 10 debris-flow events (DFEs) since 4000 cal yr BP. The mean recurrence interval between events was 433 +/-44 years, but intervals range from 724 to 20 years. The four most recent events have the shortest recurrence intervals. The largest event had an estimated sediment volume of 97,000 m3 and occurred at about 285 cal yr BP (1665 AD) during the Little Ice Age. The most recent debris-flow event that was triggered by rainstorms following the Duncan Fire was about 8x smaller than the largest event. These results may indicate that the largest DFE was triggered by an exceptional meteorological event that occurred during a cool, wet time, and that smaller DFEs were triggered by less exceptional meteorological events that occurred following wildfires.
dc.format.mediumborn digital
dc.format.mediumproceedings (reports)
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado School of Mines. Arthur Lakes Library
dc.relation.ispartofSeventh International Conference on Debris-Flow Hazards Mitigation - Proceedings
dc.relation.ispartofAssociation of Environmental and Engineering Geologists; special publication 28
dc.rightsCopyright of the original work is retained by the authors.
dc.sourceContained in: Proceedings of the Seventh International Conference on Debris-Flow Hazards Mitigation, Golden, Colorado, USA, June 10-13, 2019, https://hdl.handle.net/11124/173051
dc.subjectdebris flow
dc.subjectfan
dc.subjectmagnitude
dc.subjectfrequency
dc.subjectWashington State
dc.title4000-year history of debris flows in north-central Washington State, USA: preliminary results from trenching and surficial geologic mapping at the Pope Creek fan
dc.typeText
dc.publisher.originalAssociation of Environmental and Engineering Geologists


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