ABSTRACT
In Chapter 2 we studied specific energy from the idealized perspective of a frictionless, horizontal channel. In Chapter 3, we continued to analyze frictionless systems except that we found that energy was lost within a hydraulic jump. In this chapter, we finally relax the assumption of a frictionless channel and explore two commonly used friction equations-Chézy’s and Manning’s equations. The fundamental concept of normal depth is introduced, and how it arises in open channel flow analogously to the concept of terminal velocity in projectile motion is examined. We explore how normal depth varies as a function of the conditions in the channel: discharge, roughness, channel size and shape, and channel slope. To conclude the chapter, a reach classification system is developed that is largely dependent on the relative magnitudes of normal and critical depth.
