Experimental Studies on Determination of Discharge Capacity of Circular Labyrinth Weirs Located on A Straight Channel

Labyrinth weirs are particularly wellsuited for spillway rehabilitation where dam safety concerns, freeboardlimitations, and a revised and larger probable maximum flow have requiredreplacement or modification of the spillway. Labyrinth weirs with multiplecrest elevations can be used in spillway design to confine base flows to asection of the crest and/or satisfy discharge hydrograph requirements.Labyrinth weirs provide higher discharge capacity than conventional weirs, withthe ability to pass large flows at comparatively low heads. Over past 50 yearsmany research investigations have considered the hydraulic performance of labyrinthweirs, particularly as dependent on the geometric features. The previous workhas improved the design basis for such weirs. In the present study, dischargecoefficients were experimentally determined for both sharp crestedsemi-circular labyrinth weirs and trapezoidal labyrinth weirs of side wallangle (α=370).A comprehensive laboratory study including 9 models was conducted to determinethe discharge coefficient of the semi-circular labyrinth weirs. It was foundthat from this experimental study the discharge coefficient of the circularlabyrinth weir is higher than that of the linear weir, but lower than that ofthe trapezoidal weir.