Labyrinth weirs are among the important hydraulic structures for regulating the water level and discharge in channels, rivers and dams reservoirs. Labyrinth weirs are used in regions where there is no enough space for increasing the weir width. Many factors affect labyrinth weirs. Ratio of head to weir height is one of the most important ones which is addressed. in this research via use of a numerical model investigating water level profile and stage-discharge curve in labyrinth weirs with triangular, trapezoidal and curved planform shapes. It was observed that in a fixed head, discharge from a curved weir is higher than trapezoidal weir which is higher than triangular one. This difference in performance is for long heads is too small. In practice there is no significant difference in discharge of these weirs in high heads. Weirs with H/P>0.9, have the same performance and the shape does not influence the discharge.

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