Effects of Fines in Gravel Bed Streams Behavior

by Panayiotis Displas, Univ of Minnesota, St. Anthony Falls, Hydraulic Lab, Minneapolis, MN, USA,
Gary Parker, Univ of Minnesota, St. Anthony Falls, Hydraulic Lab, Minneapolis, MN, USA,



Document Type: Proceeding Paper

Part of: Water for Resource Development

Abstract:

A model-gravel bed stream is studied in the laboratory. Flow visualization of bedload motion correlates with bursting phenomena near the bed. The bedload variation as a result of the addition of fines correlates with the amount of fines in the subpavement and pavement. Initially the fines collect in the immediate subpavement, and consequently reducing the bedload rate. This trend is continued until the top of the subpavement has been saturated with fines, and a significant quantity of fines appears in the pavement. Then the bedload rate increases, due to the higher mobility of coarse particles moving over a surface rendered smooth by the filling of the crevices between roughness elements with fines. As the original gravel bed is buried below a sand bed, the bedload transport rate once again decreases, as a result of the reduced availability of grains from the original bed.

Subject Headings: Bed materials | River and stream beds | Bed loads | Pavements | Hydraulic roughness | Sediment transport | Pavement surface roughness

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