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The effect to the river environmental preservation of artificial flood in Satsunai River
Published in Silke Wieprecht, Stefan Haun, Karolin Weber, Markus Noack, Kristina Terheiden, River Sedimentation, 2016
Y. Watanabe, K. Sumitomo, S. Yamaguchi, H. Yokohama
In the case without artificial flood (Case 4), the excavated entrance of the anabranch was maintained, but a tendency of accretion was seen in the anabranch and the main channel was scoured, as shown in Figure 8(a) and Figure 9(a). As a result, it is predicted that the river channel form becomes a single channel. In the case with artificial flood (Case 5), the entrance and watercourse downstream of the entrance were eroded, and clear braided streams, where water flowed into the anabranch, were created, as shown in Figure 8(b) and Figure 9(b). In a snowmelt flood, sediment deposition readily occurs during the discharge decrease period in sections of the watercourse where the flow velocity is low and the water depth is shallow. The artificial flood, which has a greater peak discharge and greater differences between the highest and lowest discharges than those of the snowmelt flood, caused more erosion than accretion in the anabranch. The riverbed disturbance caused by the artificial flood in a short period of time is thought to have contributed to the maintenance of the anabranch.
Bedload and channel morphology along a braided, sand-bed channel: insights from a large flume
Published in Journal of Hydraulic Research, 2019
Robert Ettema, Dylan L. Armstrong
Bar formation and confluence development significantly impacted the braiding pattern. Time-lapse photographs showing the evolving formation and eventual decay of a bar document bedload and bar influence on anabranch formation (Armstrong, 2017). The process of bar formation typically occurred over a 1.5-h period. As a bar enlarged, it progressively retarded flow along a main anabranch and diverted flow, which subsequently eroded a substantial portion of the bar and forming vertical banks, as a new anabranch grew. As the bar eroded, sediment transport visibly increased downstream along the new, main enlarging anabranch.