Experimental Study of the Effects of Hydraulic and Geometric Parameters of the Sediment Transport Tunnel on the Deviation Flow and Transmitted Sediment

In recent decades, although dam construction has been increased, but most of them have experienced huge sedimentation problems during operation. To solve this problem scientifically and efficiently, Sediment Bypass Tunnels (SBTs) could be incorporated. SBTs are division channels that transfer the flow containing sediments from the upstream to the downstream of the dam reservoir. In this experimental study, the effect of division channel width on deviated flow rate and sediment rate into the secondary channels has been investigated. For this purpose, Froude number and flow depth as variables were studied in three different widths of the diversion channel. The results of this study reveals that increasing Froude number reduces the deviated flow rate and sediment rate to the lateral channel up to 20 and 44% respectively. On the other hand, 33% width reduction of the diversion channel could result a reduction of 8.5% in the deviated flow rate and 50% increase in the width could increase 13% the deviated sediment rate into the lateral channel. The performance index was greater than one and ranged from 1.6 to 3.77. Hence the 90-degree diversion channel has a good performance for sediment transportation. By decreasing Froude number and increasing flow depth in a diversion channel (with dimensionless width=0.41), it is possible to find the optimum choice for sediment transportation by which the highest sediments could be deviated by the lowest deviated flow rate.