[1] Bed surface coarsening was found to be an important effect for the formation of ripples and the dynamics of the boundary layer above a predominantly silt-sized sediment bed (median particle size equal to 26 mm; 20% fine sand, 70% silt, 10% clay) under oscillatory flow (with orbital velocities of 0.32–0.52 m/s) in a laboratory wave duct. Following bed liquefaction, substantial winnowing of t...

[1] Mountain rivers in particular are prone to sediment input in the form of pulses rather than a more continuous supply. These pulses often enter in the form of landslides from adjacent hillslopes or debris flows from steeper tributaries. The activities of humans such as timber harvesting, road building, and urban development can increase the frequency of sediment pulses. The question as to ho...

Representative bed material samples were taken from the two gauging sites on rivers omi for sieve analysis to obtain the grain size distribution of its bed materials. The analyses of the grain size distribution showed that the bed load accounted for 9% of the total estimated suspended sediment load of 1,703, 548.113 kg/annum in river omi. River omi bed material had a geometric mean particle siz...

[1] Independent lithologic and structural controls in fluvial bedrock systems interact with coarse sediment transport processes to play a key role in bedrock incision processes such as abrasion. During a 3 year study on the Ocoee River in the Blue Ridge Province of the southern Appalachians, USA, we used painted tracer clasts to measure coarse sediment transport dynamics and address whether dif...

A longstanding problem in the study of sediment transport in gravel-bed rivers is related to the physical mechanisms governing bed resistance and particle motion. To study this problem, we investigated the motion of coarse spherical glass beads entrained by a steady shallow turbulent water flow down a steep two-dimensional channel with a mobile bed. This experimental facility is the simplest re...

Like many montane rivers in the western U. S., the Middle Fork of the John Day River is characterized by alternating narrowand wide-valley segments. Although the river has a low gradient (generally < 0.01) alluvial channel, changes in valley width exert a clear infl uence on channel morphology. A spatial hierarchical model of channel morphology was applied to the Middle Fork to understand reach...