Developing a Simple Unique Stage-Discharge Equation for Labyrinth and Normal Side Weirs with Different Angles and Openings

Side weirs are among important hydraulic structures that used in various projects such as water conveyance, flood control, and diversion of excess water in sewer networks. One of the most effective and economical way to increase the efficiency of this weirs is application of labyrinth side weir. Using labyrinth side weirs, the flow discharge is increased by changing the plan geometry and increasing the weir length. According to fairly complicated flow pattern around this weir, extracting simple stage-discharge relation for different conditions is necessary. Therefore, in this study, the stage-discharge relations for normal side weirs with opening of 0.3 and 0.5 and labyrinth side weirs with included angles 90, 60 and 45 and opening of 0.3, 0.5 and 0.6 were extracted. Comparison of simulated results with these relations indicated that accuracy of the relations is within ±15% which is acceptable for practical purposes. Due to decreasing the weir effective length, the flow discharge was reduced when the apex angle of labyrinth side weir has increased for a constant water head. Decreasing the effective width also caused the flow discharge to be reduced when opening was decreased for a constant water head.