Abstract
Streamwise canyon of the roughness layer in armored bed of the dam-downstream river actually relates to the movement of sand. Wind tunnel experiments were conducted by changing the spacing of the rib structure of the roughness to clarify the bottom shear force in the streamwise canyon where flow is accelerated. The result shows that when the spacing is large, velocity near the bottom is high and the velocity is in logarithmic distribution. On the other hand, when the spacing is small, the velocity is in dog-legged distribution. The result indicates that separated eddies from the rib structure could narrow the flow accelerated region in the streamwise canyon. In addition, the average values of the shear force correction coefficient k have been obtained from 1.0 to 0.8 by using observed friction velocity and calculated one, and by calibrating the amount of bed load transport.
