An experimental study to determine the effects of particle size and bifurcation angle on the distribution of flow and sediment transport parameters in a bifurcated channel.

Abstract Flow and sediment sharing in a bifurcated channel are considered to be a very important issues in river engineering and flood management. The present study has been conducted based on the field bifurcation of the Kangsabati river bifurcates at Kapastikri, about 75 km downstream of Kangsabati reservoir of West Midnapore, West Bengal, India. A scaled physical model simulating bifurcation region was conducted on a fixed-bed model at the Laboratory of River Research Institute (RRI), West Bengal (WB), India. The model set-up has been run with a range of discharges, including low, moderate, and high with three different sets of bifurcation angles. Furthermore, three different sizes of sediment of varying densities have been used to find the transport capacity of sediment for individual bifurcated angle. A set of data have been collected for different conditions like varying discharge, angle of bifurcation, mean size of sediment () particle and a comprehensive analysis have been done with respect to collected data to see how discharge and sediment load (bed-load) are distributed over the bifurcated branches. The present physical model study has determined the optimum discharge in the main channel for which the sediment and discharge get equally distributed over the bifurcated branches. The experimental data confirm that the distribution of bed load is dependent on the shape of the bifurcation and the sediment transport ratio ( s 1 /s 2 ) is sensitive to the angle of bifurcation in which s 1 & s 2 represent sediment transport rate (kg/hr) in respective branches.