Correct option is B
Garret's diagram
It is graphical representation of design of canal dimensions based on Kennedy theory.
The diagram is discharge plotted on abscissa (X-axis), and slope of the channel on the left side of ordinate (Primary Y-axis) and depth of the channel and critical velocity on the right side of the ordinate. (Secondary Y-axis).
Garret's diagram is applicable only for side slope of the channel of 0.5: 1.
The diagrams are specified for manning's coefficient (N) of 0.0225. However, these charts can be extended to any value of N using a nomogram at the top of each diagram.
