HYDRAULIC MODEL EXPERIMENTS ON THE EFFICIENCY OF THE DRIFTWOOD CAPTURE WORKS

Abstract

This facility plan is one of the project at the Ono River, Oita prefecture, a tribute of the Kagetsu River in the Chikugo river basin and related with the disaster of heavy rain in north Kyushu occurred in July 2017 that caused transport and accumulate of driftwood on bridges etc. In this study, the structure features such as position, shape or height of side overflow weir that can capture driftwood into catchment area efficiently was examined. It is found that there is a correlation between distributary rate and capture rate, so we aimed to increase distributary of water and driftwood into catchment area and drain water from catchment area efficiently. As a result, we shortened the length of upstream side bank between main stream and catchment area, replaced downstream side one into slit, and raised riverbed of main stream. The results show that the capture rate improved up to 50-70％ from 10-20％ on original plan.