The Effect Of Uniform Reed Population To The Open-Channel Flow

The author uses the natural reeds as experimental material and plants them in a simulant indoor watercourse. The impact of reed population on the velocity distribution and turbulence intensity is studied under the discharge of 70,80 and 90L/s through 6 cross-sections and 3 longitudinal-sections, with reeds at the density of 0,54,108 and 202s/m2. The results show that (1) the standard deviation of instantaneous velocity is larger within the reed population, the time-average velocity increase in a devious way from the bottom to the surface, and such a distribution does not fit well the power-law function; (2) on the midline of the channel, the difference of the internal and external velocity becomes larger when the reed density increases to 202 s/m; (3) the turbulence intensity becomes larger when the reed population is denser or at the junction of the water flow and reed population; (4) in the control experiment, the turbulence intensity increases with both the discharge and the distance to the channel-walls, while it is the contrary with the involvement of vegetation groups; (5) when the flow passes through the reed population, the turbulence intensity significantly decreases and the flow becomes more stable. This study enhances the understanding of the interaction between the reed and flow in an eco-watercourse.