Abstract
A lot of groynes are set up in Tonegawa. Recently, the groyne of the megalith volume in the Maebashi Park and the water passage part maintained as one body is constructed to the hemicycle among those to make a close contact with water image. There is a report that the scour damage of the shore protection and the existing groyne had generated at the flood decreased after constructing them. It is understood that the large-scale separating flow is formed in the downstream part around a hexahedron groyne to which the cylinder shape was put out according to a current finding. In the present study, the control effect of the flow decided to be clarified experimentally for the hemicycle groyne. As a result, the effect of avoiding water weakens more than a hexahedron groyne by setting up the hemicycle groyne. The range of the ascending current generated in the groyne downstream decreases as for the flow velocity decrease rate of the groyne of the hemicycle large from a hexahedron groyne.
