Author(s): Sumida Hideyuki; Muto Yasunori; Tamura Takao
Linked Author(s): Yasunori Muto
Keywords: Weir; Bed morphology; Partial removal; Experiment; Sand bar
Abstract: River crossing structures have contributed to flood control and irrigation. However, they adversely affect the river’s biota and sediment transport. Recently methodology of full or partial removal of a weir in order to eliminate discontinuity of the river is under consideration. Nevertheless, impact on bed morphology and channel development due to the removal has not been fully explored. In this paper flume experiments were conducted to study effects of partial removal of a weir on bed morphology in its upstream. The depth and width of the removed part were systematically changed. The sand bar formation and bed degradation were focused in the upstream. In the downstream, a local scouring beneath the weir opening was remarked. It is found that the channel is formed at the center of the flume by partial removal. In comparing the systematic changes of the removal depth and width, it was noted that changes of the removal depth affects in wider area than the removal width. Moreover, the results revealed a channel deformation process after the partial removal. The results indicate that partially removed weir can improve sediment movement from the upstream to downstream. The downstream side, the relationship between the shape of removal and the deepest bed level of local scour was not confirmed. Since the various bed shapes can be formed by the partial removal, there is a possibility that can contribute to improve habitats of river organisms, such as riffle-pool structure and a smooth slope by deposition along the bank side.
Year: 2014