Question

A bridge culvert is to be constructed across a proposed lined canal. The afflux at this site for a contracted canal width can be computed by __________

(a) Unwin’s formula

(b) Broad-crested weir formula

(c) Orifice formula

(d) Molesworth formula

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I want to ask this question from Small Road Bridges Construction topic in division Culverts and Small Road Bridges Construction of Irrigation Engineering

Answer 1

The correct answer is (d) Molesworth formula

The explanation is: The afflux for non-erodible beds may be easily computed by using the Molesworth empirical formula given as-

h = [V^2/17.88 + 0.01524] [(A/a)^2 – 1]

Where, h = afflux in meters, V = velocity in an unobstructed stream in m/sec, A = unobstructed sectional area of the stream in sq.m and a = obstructed reduced c/s area of the stream at the bridge site.