Submergence effect on flow and resistance due to a single groyne

Groynes have been used for the protection of banks, stabilization of bed morphology and also for establishing navigation channels. A typical Japanese river is characterized by large and sudden variations in discharge due to big amounts of rainfalls, so that the groynes are often in submerged condition. The present study focuses on the effects of submergence on the mean flow pattern and resistance around a single groyne. The PTV method and numerical shallow flow analysis are adopted in order to calculate velocities accurately. The flow pattern and flow resistance are estimated by comparing velocities at several points between upstream and downstream of groyne. The relations between flow resistance and submerged flow depth are discussed in the present study.