ANALYSIS BASED ON LONGITUDINAL PROFILE OF FRICTION VELOCITY FOR A GRAVEL RIVER BED VARIATION AFTER EXCAVATION

Abstract

To confirm the applicability of river bed variation estimating with quasi-2D non-uniform flow calculation, we investigate relationship of actual river bed variation and longitudinal profile of friction velocity ratio of after to before river bed excavation. In the result, reach-scale profile of the ratio gives acceptable agreements with actual river bed variation after excavation. Furthermore, to estimate river bed variation around bend section, we also conduct the flood flow computation with a general-coordinate 2D current model. The result indicates that noted river bed degradation after excavation is involved in progress of gravel bar after river improvement plan, and shows the importance of monitoring in excavated river.