Question

A discharge of $72m^3/s$ is to be allowed through siphon spillways of 2 m width and 75 cm depth with a working head of 8 m. The number of spillways to be provided will be (Take coefficient of discharge for the spillways = 0.64)

• A. 2
• B. 4
• C. 6
• D. 8

Answer 1

The correct option is C 6

Discharge through one syphon spillway is given by

$Q=C_d.A\times \sqrt{2gH}$

$=0.64\times 2\times 0.75\times \sqrt{2\times 9.81\times 8}$

$=12.02m^3/s$

$\therefore \text{Number of spillways}=\frac{72}{12.02}=5.98\simeq 6$