礫の形状が河川中流域における土砂の分級におよぼす影響

抄録

This research showed that shape of a gravel has an effect on its transportation pattern and deposition area. A circular gravel has small critical tractive force and can be transported very quickly. It tends to roll and move linearly by inertia force. A flat gravel has larger critical tractive force and is transported slowly. It tends to slide and move smoothly along a streamline. These trends affect the sorting process in a river channel. Circular gravels are deposited on the upstream side of a weir where tractive power decreases. Flat gravels are deposited on the downstream side of a weir where is being eroded. Circular gravels move linearly and they tend to be deposited on the upstream edge of a dry riverbed. Since these sorting patterns occur during a recession period of a flood, they are not seen particularly in a river which has a sharp hydrograph.