Analysis of flow velocity distribution in vegetation channels with different densities

Predicting and analysing flow in the vegetated channel and wetland is the main challenging environmental and hydraulic problem. It is due to the high dependency of the hydraulic properties of the flow to the physical structure, density, and distribution of vegetation in wetlands and channels In this study, velocity profiles are investigated in emerge vegetated channels with considering density effect. The experiments were performed in a laboratory flume with vegetation called Eleocharis and three different types of densities. This study aims to provide a comprehensive analysis of velocity profiles in emerged vegetation channels in the presence of real plant species and to provide a more accurate relationship. Therefore, studies were performed in a laboratory flume with a rectangular cross-section 20 meters long and 1.5 meters wide with a fixed floor slope of 0.005, in which a type of vegetation called Eleocharis was used in three types of low, medium, and high density. The results showed that the velocity in the upstream areas is the lowest which on average shows an average velocity in the upstream compared to the downstream for different densities of about 4 to 12 percent. Meanwhile, the average velocity decreases by increasing the plant density from 23 to 42 and from 42 to 72 about 12 and 4.5 percent in the upstream and about 11 and 4 percent in the downstream, respectively. Also, to estimate the average flow velocity in the vegetation area, a modified relationship was presented which has acceptable accuracy. The application and accuracy of this relationship in artificial wetlands and channels are important to eliminate runoff pollution and sedimentation.