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Incipient sediment motion across the river to debris-flow transition

Jeff P. Prancevic, Michael P. Lamb and Brian M. Fuller
Incipient sediment motion across the river to debris-flow transition
Geology (Boulder) (January 2014) 42 (3): 191-194


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 approximately 22 degrees , 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.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 42
Serial Issue: 3
Title: Incipient sediment motion across the river to debris-flow transition
Affiliation: California Institute of Technology, Division of Geological and Planetary Sciences, Pasadena, CA, United States
Pages: 191-194
Published: 20140110
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 33
Accession Number: 2014-009746
Categories: GeomorphologyEnvironmental geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2014067
Illustration Description: illus.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201407
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