عنوان مقاله [English]
An important tool in current multi-purpose erosion control, stream restoration, and habitat improvement projects is the bendway weir. A series of upstream-angled low-elevation stone sills (bendway weirs) are designed to control and redirect currents and velocities throughout a bend of a river or stream. Consideration of scour and sedimentation pattern at a 90 degree bend (with relative radius of curvature equal to 3.3) in the presence of weirs and without weirs is the aim of this study. To reach the purpose of this study, series of bendway weirs (7 weirs) with height of 30, 50 and 70 percent of flow depth were constructed in multiple flow conditions at the outer bank side. The inclination angle, length and distance of weirs were kept fixed in all tests, and set equal to 60 degree, 30 percent of canal width and three times of weir length, respectively. The results showed that the channel talweg moved as effective length of weir from outer bank to the center and along the weirs tips at the result of bendway weirs installation. Owing to installation of bendway weirs with 0.5D and 0.7D height the scour volume accessed 53% and 120% higher than no-weir state, respectively. While for weirs with 0.3D height, it was equal to no-weir condition. Also, the maximum relative scour depth at the tip of weirs with height of 0.5D and 0.7D were two times of weirs with 0.3D height.
Key words: Bend Migration, Erosion Control, Height of Bendway Weirs, Local Scour,
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