Spur dikes were expected to create new aquatic habitats according to produce local scour and sediment deposition area around them on the movable bed. However, when the spur dikes were set on the rigid bed for creating new aquatic habitats, it was not known the potential ability to accumulate sediment deposition behind spur dikes. In this study, we conducted experimental flume tests and numerical analysis to confirm the characteristics of flow, sediment transport and bed deformation around the spur dikes on the rigid bed. These results showed that the sediment was not deposited behind the spur dikes, because the sheer stress is smaller than the critical sheer stress in the upstream area of the spur dikes, so that all bed materials were transported to the opposite bank side. However, when the flow is under unsteady condition, it is confirmed that the no sediment transport area is reduced because the large transverse water surface gradient is formed in the downstream area of the spur dikes during the increase process of water discharge and would change the direction of sediment transport material.
