Abstract
These days, 2-D numerical simulation are used for river management. However, estimating sediment deposition inside vegetated area of a river is still one of the most important research topics for river management. In this paper, the series of flume experiments would have been taken in order that the way how to estimate shear velocity inside vegetated area is investigated. Firstly, the results of some trial experiments led how to take experiments to measure the flow velocity distributions with PIV. The series of experiments were taken, and the vertical distribution of flow velocity and Reynolds stress inside rigid vegetated area, especially near channel bed, could be measured. These results indicated that the vertical distribution of the flow velocity have three regions : the upper region where the averaged velocity takes a fixed value controlled by vegetated area condition; the region near bed surface where the velocity should be controlled by bed roughness; the transit region between the upper and lower region. The vertical distribution of flow velocity and Reynolds stress inside rigid vegetated area were investigated in detail. These results indicate that Reynolds stress changes linearly in the region near bed surface, and the flow velocity distribution follows the logarithmic law. And also these experimental results indicated that shear velocity are evaluated by the weight of thickness of the region near the bed surface under the condition of hydraulics rough boundary. On the other hand, more investigation of detail velocity distribution on the hydraulics smooth boundary are needed.
