Experimental Study on suspended sediment deposition process in Karkheh dam reservoir

One of the most essential works for sediment management in dam reservoirs is to identify the characteristics and effective parameters of deposition of sediments in the dam reservoir. In this research, the sedimentation process of fine sediments deposited into Karkheh dam reservoir was investigated in order to determine the required hydraulic conditions for desilting of the reservoir. Experiments were carried out in an annular flume located in Hydraulic Laboratory of Shahrekord University and sediment samples were taken from reservoir of Karkheh dam. Experiments were done at initial concentrations of 5, 10 and 20 g/l, and various shear stresses to determine the threshold shear stress for partial deposition and full deposition of suspended sediments. The obtained results showed that the shear stress of the initiation of sediment deposition was 0.1 N/m2. It was also found that when the flow velocity to be exceed up to 0.61 m/s, the sediments would be completely remained in term of suspension. Under these conditions, the shear stress and Froude number were obtained as 2.55 N/m2 and 0.43, respectively. Also, the results showed that in higher sediment concentrations, increasing of shear stress is more effective in the sediment deposition rate.