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Modeling Sediment Transport in Ice-Walled Subglacial Channels and Its Implications for Esker Formation and Proglacial Sediment Yields

Beaud, Flavien and Flowers, Gwenn E. and Venditti, Jeremy G. (2018) Modeling Sediment Transport in Ice-Walled Subglacial Channels and Its Implications for Esker Formation and Proglacial Sediment Yields. Journal of Geophysical Research. Earth Surface, 123 (12). pp. 3206-3227. ISSN 2169-9003. http://resolver.caltech.edu/CaltechAUTHORS:20190201-111654179

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Abstract

Sediment yields from glacierized basins are used to quantify erosion rates on seasonal to decadal timescales as well as conditions at the glacier bed, and eskers hold valuable information about past subglacial hydraulic conditions in their spatial organization, geometry, and sedimentary structures. Ultimately, eskers are a record of past glacio‐fluvial sediment transport, but there is currently no physical model for this process. We develop a 1‐D model of morphodynamics in semicircular bedrock‐floored subglacial channels. We adapt a sediment conservation law developed for mixed alluvial‐bedrock conditions to subglacial channels. Channel evolution is a function of melt opening by viscous heat dissipation from flowing water and creep closure of the overlying ice, to which we add the closure or enlargement due to sediment deposition or removal, respectively. We apply the model to an idealized land‐terminating glacier and find that temporary sediment accumulation in the vicinity of the terminus, or the formation of an incipient esker, is inherent to the dynamics of the channelized water flow. The alluviation of the bed combined with the pressurized channel flow produces unexpected patterns of sediment evacuation: We show that the direction of hysteresis between sediment and water discharge is not necessarily linked to a supply‐ or transport‐limited system, as has been hypothesized for proglacial sediment yields. We also find that the deposition of an incipient esker is a function of a compromise between water discharge and sediment supply, but perhaps more importantly, ice‐surface slope and the temporal pattern of water delivery to the bed.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2018jf004779DOIArticle
https://researchdata.sfu.ca/pydio_public/beaud_etal_jgr_simulation_repoRelated ItemSumlations
https://bitbucket.org/Flavien/beaud_etal_jgr_code_r-channel/src/master/Related ItemCode
ORCID:
AuthorORCID
Beaud, Flavien0000-0002-0687-8741
Flowers, Gwenn E.0000-0002-3574-9324
Venditti, Jeremy G.0000-0002-2876-4251
Additional Information:©2018. American Geophysical Union. Received 1 JUN 2018. Accepted 14 NOV 2018. Accepted article online 16 NOV 2018. Published online 6 DEC 2018. We would like thank the editor in chief, Bryn Hubbard, as well as two anonymous reviewers for their constructive comments on the manuscript. Funding was provided by the Swiss National Cooperative for the Disposal of Radioactive Waste (Nagra) within the framework of investigating ice‐age effects related to the long‐term safety of radioactive waste disposal. Funding was also provided by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canada Research Chairs Program, and Simon Fraser University (SFU). F. Beaud would like to acknowledge funding from the Swiss National Science Fund through an Early‐Mobility postdoctoral fellowship. The simulations used for the paper can be downloaded here: https://researchdata.sfu.ca/pydio_public/beaud_etal_jgr_simulation_repo. The code can be dowloaded from the following repository: https://bitbucket.org/Flavien/beaud_etal_jgr_code_r-channel/src/master/. The authors declare no conflict of interest.
Funders:
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Canada Research Chairs ProgramUNSPECIFIED
Simon Fraser UniversityUNSPECIFIED
Swiss National Science Foundation (SNSF)UNSPECIFIED
Swiss National Cooperative for the Disposal of Radioactive WasteUNSPECIFIED
Subject Keywords:Sediment transport; Subglacial hydrology; Glacial erosion; Esker; Glacio‐fluvial processes
Record Number:CaltechAUTHORS:20190201-111654179
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20190201-111654179
Official Citation:Beaud, F., Flowers, G., & Venditti, J. G. (2018). Modeling sediment transport in ice‐walled subglacial channels and its implications for esker formation and proglacial sediment yields. Journal of Geophysical Research: Earth Surface, 123, 3206–3227. https://doi.org/10.1029/2018JF004779
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92564
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:01 Feb 2019 22:31
Last Modified:03 Jun 2019 16:14

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