A labyrinth weir is one of the most effective ways of increasing weir discharge efficiency compared with a linear overflow structure. In this study, two proposed models of labyrinth weir, one with a dentate crest and another with a row of orifices along and below the crest edge were compared with a simple labyrinth weir, measuring their effects on the discharge coefficient. Experiments on nine labyrinth weir models were conducted in the hydraulic laboratory flume. These experiments indicated that creation of both dentate crest edge and row of consecutive orifices led to an increased discharge coefficient of between 11 to 25.3% and 31.6 to 52.9%, respectively, relative to simple labyrinth weir. By increasing the upstream head water, the discharge coefficient for the labyrinth weir model with dentate crest and the model with a row of consecutive orifices are closer together and eventually will converge.
