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Erosion and sedimentation patterns associated with restoration structures of bendway weirs

Hemmati, Mohammad, Daraby, Pejman
Journal of hydro-environment research 2019 v.22 pp. 19-28
rivers, sediments, topography, weirs
Bendway weirs (B.W.), known as new and innovative river training structures, are positioned from the outer bank of the river bend and angled upstream toward the flow. In order to investigate the effect of bendway weirs on the sediment process, experiments were conducted in a 90° bend with a relative curvature of 3.3 with and without bendway weirs. Following the installation of bendway weirs with different crest slopes, the scour and sedimentation patterns were evaluated under clear water conditions. To this end, a series of B.W. (7 weirs) with three crest slopes (0, 5, and 10 percent) were installed at the outer bank side in different hydraulic conditions. Erodible bed topography measurements revealed that the maximum scour depth occurred at the tip of the first and last weirs. Moreover, the findings of this study clearly demonstrates the potential of bendway weirs in modifying morphology of river bends and their efficiency in reducing erosion and sedimentation. In general, compared to non-weirs condition, the eroded sediment volume increased by 53, 36, and 15 percent due to the installation of weirs with crest slopes of 0, 5, and 10 percent, respectively. Finally, this study revealed that the maximum scour depth decreased with an increase in the crest slope.