ABSTRACT
The Kakogawa River, which has a catchment area of 1730 km2 and a length of 96.0 km, flows through Hyogo Prefecture in Japan. The influence of runoff due to barrage water and the Mino River tributary, combined with a meander in the river upstream from the large barrage on the Kakogawa River (Kakogawa Barrage), has promoted the development of a sandbar on the riverbank opposite the confluence. This sandbar, which has enlarged and become fixed, currently deflects the passage of water back to the left bank and has decreased the river’s usable water-surface area. To wash away the sandbar, a groin was installed in 2015. The purpose of this study was to survey the river’s topography in the vicinity of the Mino River confluence and identify the factors responsible for sandbar development using model experiments and numerical analysis. In addition, the function of the groin and the effects of changing its characteristics were verified.
