Scenes from 'Bedload Transport of Binary Mixtures of Coarse Sand and Fine Gravel' used by permission (Copyright 1990 by Ronald L. Shreve and Thomas G. Drake; produced with support from the Donors of the Petroleum Research Fund).
Total Time &endash; 1:26 (14.7 MB)
First part shows the process of bedload sheet migration in water flow for a 100% sand bed (compare with bdld.mov). These low amplitude patches of material move down flow without an avalanche face (i.e. sheet face is less than angle of repose), over time they steepen to a true avalanche foreset. Sand transport is shown at three scales.
Second part shows down flow migration of sandy avalanche foresets. The topography of the starting bed is shown with a yellow line and provides a useful measure to see aggradation/progradation rate. Sand is transported along, or slightly above, the bed. Beyond the brink point, grains settle onto the foreset. After building up a bit some avalanche down slope.
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