Sediment Trap in the Downstream of Check Dam: The Effect of Changes in Channel Depth on Sediment Deposition

Reservoir sedimentation is a major problem experienced by reservoirs in Indonesia. Reservoir sedimentation can be overcome by reducing the amount of sediment that enters the reservoir, among others, by building a Check dam. Check dam deposits more sediment loads with coarse grains, while sediment loads with fine grains will escape and enter the reservoir. So it is necessary to have construction to hold and settle fine sediment loads downstream of the Check dam. Construction is planned like a sediment trap in an irrigation system with variations in the cross-sectional area. In this study, the cross-section was expanded by changing its depth. The purpose of this research is to determine the effect of changes in the channel depth with discharge and grain size distribution variation on sediment deposition that occurs. The calculation is done using the HEC-RAS software. Simulation results show the deeper the sediment trap, the smaller the amount of sediment deposit. The large discharge, the smaller of deposit percentage. The greater of fine sediment percentage, the less the deposit.