Author(s): Akihiro Sasao; Yasunori Muto; Takao Tamura; Takuto Nomura
Linked Author(s): Yasunori Muto
Keywords: Channel transition; Sediment discharge; The THALWEG; Sandbar; Natural and artificial impact
Abstract: River development works have put emphasis mainly on flood control for a long time but at the same time brought deterioration of river environment. Although river administrators have not fully understood the impacts on rivers by those works, people recently more require technologies that improve river environment regarding longitudinal and cross sectional forms of the channel. In this paper, we think effects of natural and artificial impacts have much to do with the fluctuation of sediment discharge. In order to confirm the effects of feeding sand on sandbar, we conducted hydraulics model tests. As a result, we clarify the floods have great effect on sediment deposition, deep dig and change of channel. In case of the sediment discharge half of the equilibrium one, it causes the thalweg fall, wavelength of sandbar is short and particle size composition is large. Whereas in case of the sediment discharge twice the equilibrium one, it causes the thalweg rise, wavelength of sandbar is long and particle size composition is small. When the mean diameter of feeding sediment is smaller, it causes wavelength of sandbar is short and fine sand deposit on sandbar. In all cases, particle size composition isn’t changed in the thalweg.
Year: 2016