Author(s): Minoru Miyake; Hiroshi Cho; Terunori Ohmoto
Linked Author(s): Terunori Ohmoto
Keywords: Driftwood; Traditional river structure; Scour; Deposition; Permeability
Abstract: Seigyu, a kind of spur dyke, is a traditional river structure consisting of wooden frames and gabions. It alters flow velocities and directions, and has been installed to prevent river bank from erosion, to enhance the diversity of river environment and so on. There is a high potential to use it in river management as a green infrastructure technology after revitalization. In actual rivers, the jamming of driftwood at Seigyu is a common phenomenon during floods, which may affect the original hydraulic function of the structure. In this study, experimental studies were carried out to investigate the effect of driftwood jamming on the bed deformation characteristics around a Seigyu. The change of the permeability of the front surface of the Seigyu and the location of jammed driftwood were considered as two key factors. In the experiments, various permeabilities were tested for the former factor. While for the latter one, four kinds of scenarios were considered, i. e. driftwood were captured evenly in the vertical direction (Pattern A), evenly in the horizontal direction (Pattern B), as an impermeable part at the top (Pattern C), and as an impermeable part at the bottom (Pattern D). Based on the experiments, the scour and deposition shapes and volumes, local bed profiles and the amount of Seigyu’s movement were analyzed. It was found that the jamming of driftwood led to an increase of bed deformations despite of permeability and jamming location.
Year: 2024