Using Combined Slots as a New Approach for Optimizing Erodible Bed Changes Around the Spur Dikes in Series

The common spur dikes, which are used for river path control and bank protection, are utilized without any slots or with additional structures such as a collar or vane. The present research has been conducted to optimize the slot position in the spur dikes' body, reduce the scour depth, and improve the sedimentation conditions using the CFD model. The numerical result was compared with the Nayyer et al. (2019) experimental outcome. Results showed that the (L_S-W-Wi, T_S-W, T_S-W-Wi) combination contained the slots in the web and wing of the first and third spur dike, and the slot at the web of the middle spur dike was found as the best combination of slots under clear-water conditions. This combination was conducted to reduce the scour depth by 6.8% and increase deposition by 52% compared to the spur dikes without slots, which causes reducing scour depth and an increase in the sedimentation rate of materials between two consecutive spur dikes in series. Also, the maximum scours depth decreases by up to 20%. The results revealed that the presence of slots in spur dike and their different positions have complicated and considerable influences on the form and morphology of the bed.

Keywords: T-shaped spur dike, L-shaped spur dike, Mobile bed, Bed erosion, Numerical simulation, Simple spur dike.