屈曲度の大きな蛇行河道の再現実験：堆積物物性の効果

抄録

Meandering channels with high thalweg sinuosity were reproduced in a small flume. A mixture of fine-grained plastic sand and kaolin clay was used for bank material. Channel patterns greatly varied depending on the clay content and water saturation of bank sediment. The relationship between the discharge and meandering wavelength in the flume is consistent with those in natural rivers. Meandering river occurred under conditions with high clay content and water saturation, and braided river occurred under conditions with low clay content and saturation. In the area where meandering is maintained, sinuosity increases with decreasing clay content and saturation. However, in between meandering and braided conditions, sinuosity was higher in the meandering condition. The difference in saturation caused the difference in mean curvature of meandering bends: lower curvature predominates in higher saturation. For reproducing a simple meandering river, it is effective to use mixture of light sand and cohesive clay with appropriate water saturation.