The Effect of Downstream Wall Slope of Curved Labyrinth Spillways on Discharge Coefficient

Labyrinth Spillways are one of the hydraulic structures to regulate and control the flow of water in canals, rivers and reservoirs. In some situations, there is no enough space for increasing the length of the weir to increase the discharge. Therefore, labyrinth spillways are one of the solutions for this problem. If the cycle of linear labyrinth spillway is located on the curve, then the crest length increases, and as a result the inlet flow condition is improved and the hydraulic coefficient increases. In this laboratory study, the discharge coefficient for different downstream wall slopes is studied. 2 different spillways with side-wall angle (6 and 11/25) and 4 downstream wall slope are studied. The results indicate that downstream wall sloping reduces the hydraulic coefficient. Discharge coefficient variations with downstream slope and flow height on spillway crest were studied. Different equations were presented to estimate the discharge coefficient of the spillway by considering the downstream slope.