Premium
Intense Granular Sheetflow in Steep Streams
Author(s) -
Palucis Marisa C.,
Ulizio Tom,
Fuller Brian,
Lamb Michael P.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl077526
Subject(s) - bed load , hyperconcentrated flow , flume , streams , geology , debris , fluvial , sediment transport , debris flow , sediment , geomorphology , hydrology (agriculture) , bedform , stream bed , particle (ecology) , geotechnical engineering , flow (mathematics) , mechanics , structural basin , computer network , physics , oceanography , computer science
Quantifying sediment transport rates in mountainous streams is important for hazard prediction, stream restoration, and landscape evolution. While much of the channel network has steep bed slopes, little is known about the mechanisms of sediment transport for bed slopes between 10% < S < 30%, where both fluvial transport and debris flows occur. To explore these slopes, we performed experiments in a 12‐m‐long sediment recirculating flume with a nearly uniform gravel bed. At 20% and 30% bed gradients, we observed a 4‐to‐10 particle‐diameter thick, highly concentrated sheetflow layer between the static bed below and the more dilute bedload layer above. Sheetflow thickness increased with steeper bed slopes, and particle velocities increased with bed shear velocity. Sheetflows occurred at Shields stresses close to the predicted bedload‐to‐debris flow transition, suggesting a change of behavior from bedload to sheetflow to debris flow as the bed steepens.