Experimental study on flow and sedimentation characteristics under the effects of low-head, run-of-river dams

Flume experiments were carried out to investigate the flow and sedimentation characteristics under the effects of run-of-river dams. Based on an image measuring technique, the flow field and sedimentation characteristics were analyzed. It was observed that the longitudinal velocity of the cross-sections behind the dam had an attenuation zone on the vertical line, which decreased when there was an increase in the flow intensity. The distribution of longitudinal and vertical velocity along the vertical line of the dam crest cross-section presented significant zoning characteristics, and the zoning boundaries were almost unaffected by the flow intensity. When water depth increased at the crest of the dam, the vortex center, in the downstream of the dam, moved towards downstream and river bed, and both its area and intensity increased. The characteristics of the sedimentation morphology were very sensitive to changes in the flow intensity. At low-intensity flow, the slope of sedimentation was close to the dam body, while at high-intensity flow, no stable sedimentation was formed finally. A dynamic and stable slope entailed sedimentation in the downstream of the dam. Due to the strong vortex at the dam downstream, dynamically stable sedimentations maintain therein, and their surface profiles approximately follow the parabola law with no observable variations among different flow conditions considered here.