Experimental study on the mechanisms of flow and sediment transport in a vegetated channel Available to Purchase

Laboratory experiments were conducted in a flume containing three types of artificial flexible submerged and emergent vegetation. Detailed measurements of velocity and sediment concentration in the channel were taken. The results showed that submerged and emergent vegetation generates a much greater resistance to flow and significantly alters the vertical distributions of velocity, especially in vegetated and downstream regions. In comparison with the non-vegetated case, the turbulence kinetic energy and Reynolds stresses in the vegetated and downstream regions were much higher, indicating strong flow turbulence and momentum exchange in these areas. The high turbulence also resulted in a nearly constant fine suspended sediment concentration in the water column for all cases, while the increased resistance caused the coarser suspended sediment concentration to decrease. In addition, sediment retention by small-height vegetation was found to be insignificant while, for a canopy of large height, significant sediment deposition was found at the upstream region of the vegetated region.