The effect of downstream curved edge on local scouring at 60 degree open channel junction using SSIIM1 model

Despite a large amount of research carried out on flow patterns in river confluences, only a few researches have focused on sediment transport. This research used 3D program (SSIIM 1) for calculating of local scouring and sedimentation at a 60 degree channel confluence. The model was tested by comparing with flow and sediment results of physical model. The results showed that the ability of model is relatively good to predict flow structure and position of the erosion and sedimentation pattern. The model was then applied to investigate the effect of downstream edge curvature with non-dimensional radius (r/w; r = radius of curvature, w = width of tributary channel) 0.25, 0.5, 0.75 and 1 with discharge ratio 0.5 and 0.66 on local scouring. The results showed that the reduction of scouring depth and sedimentation bar height for r/w = 1 comparing with sharp edge junction for discharge ratio 0.5 were 51% and 41% and for discharge ratio 0.66 were 28% and 19%.