Question

What is the range of value of Manning’s coefficient for straight alignment for cast in-situ concrete lining?

(a) 0.012 – 0.015

(b) 0.015 – 0.018

(c) 0.018 – 0.020

(d) 0.020 – 0.025

I got this question during an interview for a job.

My doubt stems from Advantages of Lining in division Lining of Irrigation Canals and its Economics of Irrigation Engineering

Answer 1

The correct choice is (b) 0.015 – 0.018

Easy explanation: In absolutely straight reaches and with relatively higher discharges lower values of Manning’s constant may be attained. For cast in-situ concrete lining, the value of n varies from 0.015–0.018 and for cement plastered masonry the value varies from 0.012-0.015.