Author(s): Haruki Watabe; Hiroshi Kisa; Kenji Hashimoto; Takahiro Itoh And Yasuharu Watanabe
Linked Author(s): Yasuharu Watanabe, Haruki WATABE
Keywords: Channel divergence Log Sand bar configuration Multiple bars Hydraulic model test
Abstract: Some research shows that multiple bars and alternating bars are generally formed by the relationship between non-dimensional shear stress, relative flow depth and bed slope (Kuroki et al., 1984). The relationship helps flow channel form consequently. It is sometimes that main and sub flow channel change alternatively starting from the point of channel divergence. In the Tottabetu River in Hokkaido, Japan, a flood exceeding the plan size occurred on between August 28th to 31st, 2016. A large amount of sediment and woody debris deposited on the riverbed, which is considered that logs deposition also could influence the sand bar configuration. In this research, hydraulic model test is carried out to consider how channel divergence relates in regime criteria of sand bar configurtaion. The influence of log movement on channel divergence is also considered. The main conclusion is as follows; (1) The data obatined near channel divergenece in the model tends to be plotted around the border of multiple bars regime. The result shows that channel divergence could be figured out from the regime criteria. (2) Logs tend to deposit uprtream of sand bars or near the water edge. In paritcular, logs depsited upstream of sand bars.
Year: 2025