The upstream and downstream profiles are not affected by the hydraulic jump, which arises between the open channel flow and the pipe flow processes. If the pipe is not completely filled, the equations for open channel flow are solved in order to determine the water shallow.

The energetic height in a profile i is determined by using the following equation:

The slope of the friction is approximated by a water level at the beginning or the height of the pressure level in the profile i. Likewise the energetic height is approximated by a water level at the beginning of profile i. If outlets or pipes are completely filled the energetic height consists of the level of pressure and the height, which describes the kinematical energy caused by velocity.

This height of kinematical energy results from the known discharge and the flow-through-area of the profile.