The part of the total stream load that is moved on or immediately above the stream bed, such as the larger or heavier particles (boulders, pebbles, gravel) transported by traction or saltation along the bottom (Bates & Jackson 1987)
The sediment that moves by sliding, rolling, or bounding on or very near the streambed; sediment moved mainly by tractive or gravitational forces or both but at velocities less than the surrounding flow
The larger or heavier particles of the stream load moved along the bottom of a stream by moving water and which are not continuously in suspension or solution