ABSTRACT
This chapter is best suited for engineers and engineering students, as the design of hydraulic control structures should be performed by engineers. Also, some of the topics in this chapter are best learned in an advanced course. All readers are encouraged to read Sections 8.1 through 8.3. In Chapter 7, we considered steady uniform ow in a channel. It was understood that the ow was turbulent; that there was considerable variability in the velocity at different points in a cross section; that some of ow might even occur in an upstream direction; and, that as the ow moved around a bend, it behaved somewhat like a roller coaster. Despite all this variability, useful estimates of the mean velocity and discharge can be obtained using a resistance equation such as Manning’s equation or the Darcy-Weisbach equation. However, there are many times when use of one of these equations is not appropriate. If we consider the energy of the ow, we will see that the following three basic types of ow can occur in an open channel: subcritical, critical, and supercritical (Figure 8.1). Uniform ow is only one kind of subcritical ow regime.
