Experimental Study of Turbulent Flows in an Open Channel with Different Vegetation Patches

Flow-vegetation interaction has been a key research topic for river management. This study aims to clarify the effects of emergent vegetation patches on water depth, large vortices which develop along the edge of vegetation zone and mean velocity distributions. Flume experiments are carried out with changing the streamwise length of vegetation belt and the lateral location of the vegetation belt. Flow visualization demonstrates the large horizontal vortices generated along the vegetation belts persist over the gap region of vegetation belt. The removal of vegetation by half in the streamwise direction is found to exert a limited effect to increase the carrying capacity of flow. The vegetation belt adjacent to side bank shows high carrying capacity because of the low velocity and inhibited lateral mixing due to the side wall. Three velocity components are measured by electro-magnetic velocimetry. The evolution of primary velocity in the streamwise direction is shown in relation to the vegetation layout.