Calculate the effective length of the spillway which consists of 6 spans having a clear width of 10 m each. The thickness of each pier may be taken as 2.5 m and the total design head on the crest including velocity head is 16.3 m. Assuming 90° cut water nose piers and rounded abutments.

(a) 55 m

(b) 60 m

(c) 65 m

(d) 75 m

I have been asked this question in an internship interview.

Origin of the question is Ogee Profile in division Spillways, Energy Dissipators and Spillway Gates of Irrigation Engineering