Resumen en español

The objective of this article is to apply the momentum principle in open channels flow as an independent methodology from other physical principles. It remedies a fault of the technical literature by the additional interpretation of hydraulics phenomena that normally are studied with the energy conservation principle. It concludes about the flow depth faced with several flow conditions or flow variations or hydraulics controls. This paper shows the momentum equation applied to the interpretation of the flow depth in several openchannel flow situations: uniform, gradually varied, and some local phenomena as transitions and hydraulic jump. Hydraulic jump equations are obtained for several cross sections in terms of the initial and sequent depth of flow.