Development of meandering streams in bank erodible channels has been observed in the Otofuke River since the construction of straight low-water-channel in 1975, in contrast to a braided streams which was the typical bed configuration of the river before. In this study, numerical experiments with a field-scale channel were performed in order to reproduce the characteristics of the development process of meandering streams observed in the Otofuke River. It is found that meandering streams caused by alternate bar formation can be appeared in widening process of low-water-channel with local bank erosion at scouring points. The numerical experiments also suggest that the meandering streams can be changed to the braided streams after the low-water-channel widened to a certain extent. |