Application of submerged vanes for sediment control at Intakes from Irrigation trapezoidal channels



Construction of the intake structures to divert some portion of flow water from a main channel causes some variations of flow conditions at the intake entrance. These variations cause the reinforcement of the eddy flow and sedimentation in the bank of the intake. An effective measure to control the entry sediment is the use of submerged vanes. Most of previous studies in this regards have been conducted in a rectangular flume cross section. Since most of the main channel has trapezoidal cross sectional shape, this study was conducted with this shape. Four different longitudinal distances equal to 4H, 6H, 8H and 10H between vanes considered. Each distance was tested under four different flow conditions (Froude number equal to 0.45, 0.55, and 0.60 and 0.66). In all tests, the flow discharge ratio was kept constant equal to 7.5 percent. Total of experiments were carried out in a main channel with trapezoidal cross section (z = 1.5), 8.2 m length, and one channel as Intake with 2.6 m length and 600 diversion angle. The results of the study show that application of submerged vanes can cause the entry of sediment to intake an average reduction of 19-31 percent. The best distance between vanes was found to be 8H.