eChapter Name: Practical Aspects of Design of Canals
9789358871494
eBook Name: CANAL DESIGN AND CONSTRUCTION
by V. K. Bairathi
Theoritical aspects of design has been discussed in chapter 1. Discharging capacity of canal is
computed by Manning Equation (1)and continuity Equation (2) (Para 1.4).
In the Manning's equation V = R2/3 S1/2 / N (Eq. 1, Para 1.4); N and R play most important role.
The effect of R has been discussed in para 1.4.1, Chapter 1. In this chapter the complexities of Manning's n (or N, also known as Manning's rougosity coefficient
or simply rougosity coefficient) and some practical aspects of composite sections and velocity in best
Mehboob, trapezoidal or rectangular sectioned channels are discussed.
2.0 Manning's Rugosity Coefficient (n)
Value of N depends upon a number of factors such as , surface roughness, vegetation, obstructions, type of lining, age of lining, erosion and damages in lining, curves, discharging capacity , perimeters, depth of flow, velocity etc. These are discussed below and commonly adopted values of n are given in tables 2.1 to 2.3.