Open Channel Hydraulics101040010108001011107Open Channel HydraulicsFundamentalsThe primary driving force for flow in open channels is gravity, rather than pressure gradients (as in pipes flowing full). The longitudinal slope of the channel bottom is therefore a key parameter in determining flow rate and flow velocity in an open channel. The specific energy of the open channel (total energy per unit weight) is described as the energy of the free surface streamline with respect to the channel bottom.
Indranil Goswami, Ph.D., P.E.: Civil Engineering All-In-One PE Exam Guide: Breadth and Depth, Third Edition. Open Channel Hydraulics, Chapter (McGraw-Hill Professional, 2015), AccessEngineering