Maintenance of the Fairway at River Confluence Using Spur Dike

Inland navigation requires a stable navigational path with least available water depth (LAD). River confluence is an important feature of a river network where two flows merge with different flow characteristics. It is the site of the natural scour phenomenon. The eroded sediment is deposited as a bar at the inner bank, reducing effective navigational width, particularly in the dry season. Existing river training works like vanes or piles installed in the main channel are problematic for navigation. Hence, in the present study, introducing a spur dike in the lateral channel is proposed to control bar formation and blockage ratio (Wb/Wd, bar width/downstream channel width). Experiments are conducted on a mobile bed model with a confluence angle (θ) of 90°. The results show a reduction in bar volume and blockage ratio by 38.5% and 22.4%, respectively, at river confluence using a 60° downstream-oriented (θs) spur dike with an effective length of (Leff) 0.2Wl (Wl is the lateral channel width), placed at a distance of 6Leff in the lateral channel from the inner corner of river junction.