Velocity distribution in open channels with submerged aquatic plant



The vegetation in channels results in the loss of energy from, and the retardance of, flowing water. However, it helps to stabilize the slopes and bottoms of open channels. Recently, vegetated channels have been utilized to improve the quality of surface water and reduce the delivery of sediment and nutrient to rivers and swales. Accordingly, understanding the velocity distribution of vegetated channels is important. The velocity distribution above the canopy is normally assumed to follow the well-accepted logarithmic law, whereas that below the canopy follows an exponential law or power law. However, logarithmic, exponential, and power laws can be affected by some characteristics of the vegetation, resulting in a highly inaccurate description of velocity distributions in vegetated channels. In this study, a velocity distribution equation that is based on probability is developed for submerged vegetated channels. An extensive series of laboratory experiments were performed using Egeria densa, and the results of earlier research on channel beds of flumes are adopted to devise and validate a velocity distribution equation. The results reveal that the developed model of velocity distribution can be used to study the effect of submerged aquatic vegetation on velocity distribution. Copyright © 2011 John Wiley & Sons, Ltd.