Submerged sluice gates may be used as discharge measuring structures in irrigation channels. One commonly used model to predict discharge under submerged gates is based on the simultaneous solution of the energy and momentum equations (EM method). The conventional assumption for the solution is that the roller forming downstream of the gate is a static bubble of water with zero net flux of both momentum and kinetic energy. Energy losses along the submerged gate flow are commonly neglected. In this study, rational analysis of the EM method shows that the roller momentum flux and the energy loss may be considerable. A novel formulation of the EM method accounting for these two phenomena is proposed. Although it yields results similar to those of the conventional method, the new method introduces rationality in the application of the EM equations for submerged gate flow and helped to critically revise the assumptions in which the conventional EM method is based. © 2013 American Society of Civil Engineers.

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