Abstract
Abstract One of the most effective approaches for bank control erosion is using bank-attached vanes. In spite of the superiority of the bank-attached vanes to spur dikes, the vanes' tips are still vulnerable to local scour caused by flow–structure interaction. In this study, slotted bank-attached vanes are proposed to reduce local scour at the tip of the triangular submerged vane. For this, a rectangular slot is created parallel to the chord of the vane with an area of ten percent of the effective area of the vane surface. Two types of conventional vanes and slotted vanes were installed at different angles of attack of 23, 30, 40 and 60 degrees in an arch flume. Experiments were carried out in clear water conditions with different flow regimes with Froude numbers of Fr = 0.287, 0.304 and 0.322. The results show that the slotted vane outperforms the conventional vane by reducing maximum scour depth by about 70, 20, 17 and 54 percent for different angles of attack of 23, 30, 40 and 60 degrees, respectively. The proposed slotted vane also resulted in reduction of scour hole volume around the vane and formed the scour hole away from the outer bank.
Highlights
Bank erosion is a great challenge in meandering rivers and typically occurs in outer river bends
The effectiveness of vanes in reducing near-bank velocity considering different angles of attack was investigated by Odgaard & Kennedy ( ), concluding that for a greater angle of attack than 20, a scour hole is formed at the upstream edge of the vane
As shown in the figure, for an angle of attack of 23, there is no scouring at the upstream of the vane and the scour hole is completely transferred to the downstream of the vane
Summary
Bank erosion is a great challenge in meandering rivers and typically occurs in outer river bends. Limited lateral channel migration could be beneficial for some ecosystems (e.g., Piégay et al ), unrestricted bank erosion may demolish an existing riparian ecosystem. To cope with this issue, stabilization of river banks is of great importance. There are many studies in the literature proposing different methods for bank erosion protection including spur dikes (Copeland ), riparian vegetation (Croke et al ) and different types of vanes (Bhuiyan et al ; Pagliara et al ; Odgaard , ). In recent years, submerged vanes for the protection of riverbanks have increasingly been used because of their fast and easy way of installation compared with other traditional methods like dikes and groins (Biswas & Barbhuiya ). Odgaard & Spoljaric ( ) developed a Downloaded from http://iwaponline.com/ws/article-pdf/20/6/2175/766554/ws020062175.pdf by guest
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