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. In this paper, the flow resistance and momentum transport in open channel flow with discontinuous vegetation in longitudinal direction were examined experimentally. Velocity fluctuations were measured using a particle-image-velocimetry (PIV). Results showed that the flow resistance significantly depended on the longitudinal length of cavity between vegetation zones and the reason could be explained by the difference of momentum transport through the interaction among main flow, discontinuous vegetation and cavity.
