Question

Manning’s equation is not used to calculate_________

(a) Normal depth

(b) Roughness

(c) Critical depth

(d) Hydraulic radius

The question was asked in a national level competition.

My enquiry is from Characteristics of Surface Profiles in chapter Non Uniform Flow in Channels of Fluid Mechanics

Answer 1

Right choice is (c) Critical depth

For explanation I would say: Manning’s equation is an empirical equation that applies to uniform flow in open channels. Manning’s equation is used to calculate normal depth, roughness, wetted area and the hydraulic radius.