Vegetation communities are often observed to grow in stripe pattern or patches within many stream channels. In such a situation, hydraulic engineers should examine an appropriate vegetation management system paying attention to flood control and vegetation ecosystem. On the other hand, the cavity zone along riverside is expected to produce native habitats of various ecosystems and water-friendly environment. However, effects of side cavities on flow resistance and turbulent flow structures are ambiguous. In this paper, the flow resistance and momentum transport in an open channel flow with permeable and impermeable side cavities in longitudinal direction were examined experimentally. Velocity fluctuations were measured by using a particle-image-velocimetry (PIV). Results showed that the flow resistance significantly depended on the aspect ratio of cavity. And we revealed the effects of the vegetation permeability on turbulent flow structure.
