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Incipient sediment motion across the river to debris-flow transition

Prancevic, Jeff P. and Lamb, Michael P. and Fuller, Brian M. (2014) Incipient sediment motion across the river to debris-flow transition. Geology, 42 (3). pp. 191-194. ISSN 0091-7613. doi:10.1130/G34927.1.

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Sediment transport in mountain channels controls the evolution of mountainous terrain in response to climate and tectonics and presents major hazards to life and infrastructure worldwide. Despite its importance, we lack data on when sediment moves in steep channels and whether movement occurs by rivers or debris flows. We address this knowledge gap using laboratory experiments on initial sediment motion that cross the river to debris-flow sediment-transport transition. Results show that initial sediment motion by river processes requires heightened dimensionless bed shear stress (or critical Shields stress) with increasing channel-bed slope by as much as fivefold the conventional criterion established for lowland rivers. Beyond a threshold slope of ∼22°, the channel bed fails, initiating a debris flow prior to any fluvial transport, and the critical Shields stress within the debris-flow regime decreases with increasing channel-bed slope. Combining theories for both fluvial and debris-flow incipient transport results in a new phase space for sediment stability, with implications for predicting fluvial sediment transport rates, mitigating debris-flow hazards, and modeling channel form and landscape evolution.

Item Type:Article
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URLURL TypeDescription Material Material Material Material Material
Prancevic, Jeff P.0000-0003-1890-7551
Lamb, Michael P.0000-0002-5701-0504
Fuller, Brian M.0000-0002-4647-4717
Additional Information:© 2014 Geological Society of America. Received 11 July 2013. Revision received 5 November 2013. Accepted 12 November 2013. First published online January 10, 2014. Data Repository item 2014067. Funding was provided by National Science Foundation grant EAR-0922199, the Terrestrial Hazards Observations and Reporting center (THOR) at Caltech, and the Keck Institute for Space Studies. We thank C. Tran and C. O’Toole for help with experiments. Thanks to Editor J. Spotila, M. Church, and an anonymous reviewer for formal reviews, and R. Iverson, J. Andrade, N. Lapusta, and J.-P. Ampuero for helpful informal suggestions.
Group:Keck Institute for Space Studies, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Caltech Terrestrial Hazards Observations and Reporting center (THOR)UNSPECIFIED
Keck Institute for Space Studies (KISS)UNSPECIFIED
Issue or Number:3
Record Number:CaltechAUTHORS:20140422-072755679
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Official Citation:Jeff P. Prancevic, Michael P. Lamb, and Brian M. Fuller Incipient sediment motion across the river to debris-flow transition Geology, G34927.1, first published on January 10, 2014, doi:10.1130/G34927.1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45096
Deposited By: Ruth Sustaita
Deposited On:22 Apr 2014 15:22
Last Modified:10 Nov 2021 17:00

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