TECHNICAL DEVELOPMENT FOR ENHANCING SEDIMENT FLUSHING FROM CROSS-RIVER STRUCTURE AND RECOVERY OF ALTERNATE BARS

Abstract

 The Aimoto weir interferes with the movements of gravel in the stony Kurobe River. This arises bed degradations and changes in arrangement of alternate bars downstream of the weir since 1995s flood. As a result, longitudinal dikes installed at flow attacking points are not able to work effectively. Therefore, we developed the sediment flushing channel paved with boulders for enhancing the discharge of gravels and cobbles through the sediment flushing gate of the cross-river structure. Our numerical results indicated that the sediment flushing channel was able to guide flood flow and gravels toward the sediment flushing gate. These effects mitigated the bed degradations and the changes in alternate bar patterns downstream of the Aimoto weir. Developed technique using the sediment flushing channel promotes recovery of stable meandering patterns of the alternate bars.