Abstract:
The authors experimentally studied the velocitydistribution of flows in different types of vegetations such as arbors,shrubs and grass. The experimental procedures and the principle of ADV formeasuring the local velocities are described in detail. For vegetations onthe floodplain, the authors chose plastic grass, duck feathers and plasticstraws as model grass, model shrubs and model arbors, respectively. ADV wasused to measure the local flow velocities for different typesof vegetation on the floodplain, discharges and flume slopes. All measuredstreamwise velocities follow a logarithmic distribution fornon-vegetated floodplain, and obey S-shaped distribution for vegetatedfloodplain. The S-shaped distribution divides the flow into three regions.The range of every region is related to the flow depth, lateral location andvegetation type. For different types of vegetation, the S-shapeddistribution is different. In the meantime, it is found that the velocity inthe main channel increases and that on the floodplain decreases after thefloodplain is vegetated. The increasing or decreasing degree is related tovegetation type. Furthermore, the influences of bed slope on local velocitydistribution for different types of vegetation are distinct.