Bar deposition in glacial outburst floods: scaling, post-flood reworking, and implications for the geomorphological and sedimentary record

Hdl Handle:
http://hdl.handle.net/10034/605920
Title:
Bar deposition in glacial outburst floods: scaling, post-flood reworking, and implications for the geomorphological and sedimentary record
Authors:
Marren, Philip M.
Abstract:
The appearance of a flood deposit in the geomorphological and sedimentary record is a product of the both the processes operating during the flood, and those that occur afterwards and overprinting the deposit with a record of ‘normal’ processes. Nearly half of the total discharge of the November 1996 jökulhlaup on Skeiðarársandur was discharged through the Skeiðará river. The flood deposits have been extensively reworked since, up until 2009 when the channel was abandoned, effectively leaving the Skeiðará as a terrace, when retreat of Skeiðarárjökull directed meltwater to the adjacent Gígjukvísl river system. This paper describes the creation and modification of jökulhlaup barforms in the Skeiðará river, relating the changes to post-flood fluvial processes and glacier retreat. Large compound bars formed from the amalgamation of unit bars up to 1.5 km long. The location of the compound bars was governed by the macro-scale topography of the flood channel, and their size by upstream channel width in accordance with bar-scaling theory. Jökulhlaup bars are therefore scale invariant and formed in a similar fashion to braid bars in non-jökulhlaup braided rivers. Post-flood fragmentation and reworking of the bars consistently increased the length-width ratio of preserved bar fragments from approximately two and one half to over five. These observations increase our understanding of the preservation potential and final form of jökulhlaup deposits and provide the basis for an improved model for the recognition of jökulhlaup deposits in the geomorphological and sedimentary record.
Affiliation:
University of Chester
Citation:
Marren, P. M. (2016). Bar deposition in glacial outburst floods: scaling, post-flood reworking, and implications for the geomorphological and sedimentary record. Géomorphologie: relief, processus, environnement, 22(1), 51-60. DOI: 10.4000/geomorphologie.11262
Publisher:
GFG
Journal:
Géomorphologie : relief, processus, environnement
Publication Date:
Mar-2016
URI:
http://hdl.handle.net/10034/605920
DOI:
10.4000/geomorphologie.11262
Additional Links:
http://geomorphologie.revues.org/11262
Type:
Article
Language:
en
EISSN:
1957-777X
Appears in Collections:
Geography and Development Studies

Full metadata record

DC FieldValue Language
dc.contributor.authorMarren, Philip M.en
dc.date.accessioned2016-04-19T15:30:12Zen
dc.date.available2016-04-19T15:30:12Zen
dc.date.issued2016-03en
dc.identifier.citationMarren, P. M. (2016). Bar deposition in glacial outburst floods: scaling, post-flood reworking, and implications for the geomorphological and sedimentary record. Géomorphologie: relief, processus, environnement, 22(1), 51-60. DOI: 10.4000/geomorphologie.11262en
dc.identifier.doi10.4000/geomorphologie.11262en
dc.identifier.urihttp://hdl.handle.net/10034/605920en
dc.description.abstractThe appearance of a flood deposit in the geomorphological and sedimentary record is a product of the both the processes operating during the flood, and those that occur afterwards and overprinting the deposit with a record of ‘normal’ processes. Nearly half of the total discharge of the November 1996 jökulhlaup on Skeiðarársandur was discharged through the Skeiðará river. The flood deposits have been extensively reworked since, up until 2009 when the channel was abandoned, effectively leaving the Skeiðará as a terrace, when retreat of Skeiðarárjökull directed meltwater to the adjacent Gígjukvísl river system. This paper describes the creation and modification of jökulhlaup barforms in the Skeiðará river, relating the changes to post-flood fluvial processes and glacier retreat. Large compound bars formed from the amalgamation of unit bars up to 1.5 km long. The location of the compound bars was governed by the macro-scale topography of the flood channel, and their size by upstream channel width in accordance with bar-scaling theory. Jökulhlaup bars are therefore scale invariant and formed in a similar fashion to braid bars in non-jökulhlaup braided rivers. Post-flood fragmentation and reworking of the bars consistently increased the length-width ratio of preserved bar fragments from approximately two and one half to over five. These observations increase our understanding of the preservation potential and final form of jökulhlaup deposits and provide the basis for an improved model for the recognition of jökulhlaup deposits in the geomorphological and sedimentary record.en
dc.language.isoenen
dc.publisherGFGen
dc.relation.urlhttp://geomorphologie.revues.org/11262en
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/*
dc.subjectFluvial geomorphologyen
dc.subjectIcelanden
dc.subjectBraided riveren
dc.subjectJokulhlaupen
dc.subjectProglacialen
dc.titleBar deposition in glacial outburst floods: scaling, post-flood reworking, and implications for the geomorphological and sedimentary recorden
dc.typeArticleen
dc.identifier.eissn1957-777Xen
dc.contributor.departmentUniversity of Chesteren
dc.identifier.journalGéomorphologie : relief, processus, environnementen
dc.date.accepted2015-12-21en
or.grant.openaccessYesen
rioxxterms.funderxxen
rioxxterms.identifier.projectxxen
rioxxterms.versionAMen
rioxxterms.licenseref.startdate2016-04-28en
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