Abstract
A riverside concavity tends to cause recirculation eddies and resultantly the deposition of suspended sediment. In this study, effects of spur dike placed upstream side in a main channel on flow structures in a side concavity zone were investigated. Location distance of the spur dike from the upstream end of the concavity zone and the length of spur dikes were changed under two different discharges. The flow patterns, magnitude of recirculation eddy and water exchange velocity in the concavity zone were changed by these parameters. The reattachment length of the separated wake zone behind the spur dike is important for the control of the flow structures in the concavity zone. When the reattachment point lies upstream of the downstream end of the concavity, the flow in the concavity is accelerated. The effects of spur dike are changed with water depth because the length of the separation zone behind spur dike is reduced in cases of submerged spur dike.
