Experimental study on the effect of skimming wall angle on sediment control in lateral intake

Sediment entering lateral intakes depend on flow pattern in 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 methods to change pattern and manage sediment entering lateral intake is using skimming wall. By removing sediments from intake entrance, the skimming wall reduces the volume of sediments entering the intake. To direct the flow towards intake and increase skimming wall efficiency, a spur dike is used on the opposite side of the intake. The length and angle of the spur dike were 0.25B and 60° and was located at distances 2b from intake center. In this study, the effect of skimming walls angle with the bank, a combination of spur dike and skimming walls and discharge changes on controlling sediments entering the intake, intake ratio and bed topography were investigated experimentally. The effect of the skimming walls with three angles (β1=10, 14, and 18 degrees) and a combination of skimming walls and spur dike on opposite sides of the intake was 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 spur dike, the amount of sediment entering the intake has decreased to 81%, 78.5% and 76% on average in walls with an angle of 10, 14 and 18 degrees respectively. The combination of using skimming wall and spur dike has a superior effect on reducing enterance sediments to intake than employing skimming wall alone, namely about 15% for three angles.