AN EXPERIMENT ON THE FLOW-DOWN OF DRIFTWOOD ON RIVERBEDS WITH SANDBARS

Abstract

This study focuses on the driftwood trapping function of riverside forests, aiming to clarify the behavior of flowing driftwood and verify the positions at which riverside forests in sandbars can trap driftwood effectively from the viewpoint of riverside forest management. The river channel form between two points (KP: 15.2 and 16.2) on the Tokoro River and the riverside forest vegetation conditions were reproduced in an experimental channel to enable experiments on driftwood behavior at a variety of flow rates and the trapping of driftwood by riverside forests. The experiment on driftwood trapped by riverside forests was conducted for two cases. Most driftwood was trapped by a riverside forest upstream of a sandbar. The pieces that flowed down without being trapped were caught by another riverside forest upstream of the next sandbar. The locations where driftwood was captured varied by the time of flooding, and it was found that riverside forests situated upstream of sandbars were effective in trapping driftwood.