Question

Calculate the top width of the weir wall (B’) if the head of the water over the weir wall at the time of the maximum flood is 2 m. Take the specific gravity of the floor material as 2.4.

(a) 1.7 m

(b) 2 m

(c) 2.4 m

(d) 1.3 m

The question was posed to me in an international level competition.

My question comes from Seepage Theories in division Seepage Theories and Weirs and Barrages Design of Irrigation Engineering

Answer 1

Right option is (a) 1.7 m

The explanation is: As per Bligh, the top width of the weir wall (B’) is given by B’ = H / (G-1)^1/2.

Given G = 2.4 and H = 2 m

B’ = 2 / (2.4-1)^1/2 = 1.69 m.