抄録
It is an indispensable subject to understand the formation mechanism of the plane shape of a river channel, when considering maintenance of a river channel, and it serves as the basic point of river improvement or river environment. A meandering channel and a braided stream are generally mentioned as the plane shape of a river channel. Research on these formation mechanisms has been conducted. However, the relationship between sand bars and bank erosion which governs the plane shape of a river channel has not been amply clarified. The hydraulic experiments on bar formation using an erodible bank channel were conducted in this research. When alternate bars were formed, straight channel shifted to the meandering channel. When double row bars were formed, there were a case of shifting to meandering channel and a case of shifting to a gourd type channel. When riverbank erosion starts, migration speed of bars becomes slow and the bars develop to the transverse direction. It was confirmed that the observed wavelength of meandering or a gourd type wavelength is almost double of the stability analysis result.
