POSITIVE STUDY OF GRAVEL BARS RESTORATION IN SEGMENT 1 RIVER AT AOSHIMA AREA OF THE MIBU RIVER

Abstract

In the Tenryu River, The river morphology has dramatically changed during 40 years, because of building Dams and erosion control work as Sabo, and gathering sands and gravels from rivers. Because of reduction of gravel bars and a development of riparian woods, plants that depend on gravel bars like “Kawara Nogiku” are close to extinction. Our aim is to propose appropriate measures as physical index in Segment 1 river for self-sustaining recovery of gravel bars by experimental construction at Aoshima area of the Mibu River. In this study, we found six physical index for cutting gravel for self-sustaining recovery by monitoring flood’s impact-response. And we confirm accuracy or these index by the experimental construction by impact of three floods among two years. Furthermore we found that non-dimensional critical share stress of D30 is the important physical index of renewal of gravel bars.