Experimental Study on Depth-Averaged Velocity and Bed Profile in a Braided Channel with a Mid-Bar

Abstract

Braided alluvial rivers with a mid-bar are common features occurred in alluvial river that consists of bifurcation and confluence channels. The formation of the mid-bar will affect the hydraulics of river systems in terms of velocity and bed morphology. The studies corresponding to the typical braided river with a mid-bar are still ongoing. This paper is to present the finding of depth-averaged velocity, Ud and bed profile at the bifurcation and confluence channel. A channel with a mid-bar and erodible bed was used in this research. The experimental work was carried out in the Hydraulic Laboratory at Universiti Teknologi Malaysia, (UTM). In the experiment, two types of flow which are low flow and high flow rates were considered. The study found that depth-averaged velocity distributions are influenced by flow discharge and varied at the braided channel. The highest Ud velocity is 0.35 m/s occurred at the bifurcation area and the lowest Ud is 0.2 m/s that was occurred at the confluence area. This genesis to more erosion occurred at the bifurcation area compared to the confluence area.