Experimental Investigation of the Effect of Submergence and Transitions on Stage-Discharge Relations for Lopac Gates

Lopac gates, controlling and regulating water level in irrigation canals, have recently been considered due to their practical advantages. So far, a few researches have been conducted on Lopac gate. In this study, the stage-discharge relationships of Lopac gate with different structures including no transition, sudden and gradual transition, in free and submerged condition were investigated. The experiments were performed to provide a wide range of effective non-dimensional parameters including gate angle and relative submergence. It was found that there is a relationship between the non-dimensional form of discharge () and the ratio of upstream water depth to gate opening for free condition and between the Q* and the submergence ratio for submerged conditions. In each of the above mentioned circumstances, using dimensional analysis and regression methods between the effective non-dimensional parameters, some explicit equations were presented for stage-discharge relationship of Lopac gates, with no transition, gradual and sudden transitions under free and submerged condition.