Investigating the effect of a skimming wall on controlling the sediment entrance at lateral intakes

Abstract

Sediment entering lateral intakes depends on the flow pattern at the intake entrance. Using a structure in front of the intake entrance can change this pattern and as a result the entering sediment. One of the effective method to change the pattern and manage sediment entering a lateral intake is to use a skimming wall. The removal of sediments from the intake entrance using a skimming wall led to reduction of sediment volume at the intake. To guide flow into the diversion canal and increase skimming wall performance a spur dike was utilized at the opposite side of the intake channel. In this study, the effect of the skimming wall's angle with the bank, a combination of spur dike and skimming wall and discharge changes on controlling sediments entering the intake, intake ratio and bed topography were investigated experimentally. The effect of a skimming wall with three angles (10°, 14°, and 18°) and a combination of skimming wall and spur dike on opposite sides of the intake were investigated. Conducting dimensional analysis, non-dimensional ratios were extracted and test variables were specified. Results showed that in the case of having a skimming wall combined with a spur dike, the amount of sediment entering the intake decreased by 81%, 78.5% and 76% on average for walls with angles of 10°, 14° and 18° respectively. Combining a skimming wall and spur dike has a higher effect on reducing sediments entering the intake compared with a skimming wall alone by about 15%.

Experimental Study on the Placement of the Angle and the Distance of Parallel Skimming Walls to Reduce Inlet Sediment in a Lateral Intake

“…To make a comparison between the results of the present study and comparable works, the results and findings of Barkdoll et al (1999), Raudkivi (1993), Hassanpour (2007), and Moradinejad et al (2017) were studied. Fig.…”

“…iments for a single Froude number, but he focused on a range of 0.4 to 0.6 for the Froude number. Moradinejad (2017) assumed that the value of varies Q R between 0.1 to 0.2 and that an increase Q R in leads an increase in the ratio of the deviated sediment to the intake. He showed that a 14% increase in a stream's Froude number causes an increase in the ratio of the inlet sediment ratio to the intake up to 118%.…”

“…Abbasi and Nejad-yazdi ( 2014) reported that the utilization of a sill and submerged vanes leads to a decrease in the amount of the entry of sediment into the intake up to 72% relative to the mere deployment of a sill and up to 45% relative to the mere deployment of submerged vanes. Moradinejad et al (2017) experimentally studied the flow patterns and sediment control using a skimming wall and spillway at the input section of the lateral intake.…”

Experimental study of flow pattern and sediment behavior near the intake structures using the spur dike and skimming wall

“…Sediments were weighted after 30 min. Like study Moradinejad et al (2017), to control sediments movement as bed load in selected discharge range, Shields diagram was used. The experimental conditions were as follows: minimum discharge: 0.025 m 3 /s, slope of moving bed: 0.002, flow depth: 4.6 cm, hydraulic diameter: 0.0452 m, shear velocity: 0.0298 m/s, boundary Reynolds (Re*): 25.48 and Shields parameter (θ): 0.0548.…”

“…Spur dikes are simple hydraulic structures which are used to organize river bends or their straight line. They are used to control erosion and protect river banks and are of the deviation type (Moradinejad et al 2017;Daneshfaraz et al 2015). This structure causes changes in the flow pattern due to the reduction in the flow separation at the bottom.…”