Submergence effects on head-discharge relationships for labyrinth and sharp-crested linear weirs

Considerable research has been reported describing the submergence effects on the hydraulic performance of linear weirs; however, a literature review revealed that little has been done regarding the effects on labyrinth weirs. The objective of this study was to develop a method for more accurately predicting the hydraulic performance of submerged labyrinth weirs. The currently recommended method approximates submerged labyrinth weir performance utilizing a relationship developed specific to linear weirs. This approach was found to have an average error of 8.9% in predicting the upstream head required to pass a given flow over a submerged labyrinth weir. In this study, testing was performed on a sharp-crested, linear weir and three different labyrinth weirs to determine the hydraulic performance of each under submerged conditions. From this a dimensionless relationship was developed predicting upstream head on a submerged weir with an average error 1.7%, independent of weir design.