An ogee spillway of a concrete gravity dam having FRL of 328 m and MWL of 340 m is provided with vertical gates between piers erected on the spillway. The effective length of the spillway is 60 m. The discharge through the spillway when gates are opened up to the actual reservoir level of 331.0 m will be_____________

An ogee spillway of a concrete gravity dam having FRL of 328 m and MWL of 340 m is provided with vertical gates between piers erected on the spillway. The effective length of the spillway is 60 m. The discharge through the spillway when gates are opened up to the actual reservoir level of 331.0 m will be_____________ Correct Answer 1700 cumecs

The discharge is given by the equation – Q = Cd. A. (2gH)1/2 Where Cd is the coefficient of discharge through the orifice A is the area of the opening = 60 x 6 =360 m2 H is the water head over the centre line of the opening = RL (331 – 328) = 3m Q = 0.62 x 360 x (2 x 9.81 x 3)1/2 = 1700 cumecs.

Related Questions

Statement (I): The ogee spillway is a control weir having an S-shaped crest profile which provides a high discharge coefficient without causing cavitations. Statement (II): The crest profile of ogee spillway conforms to the lower nappe of flow over a ventilated sharp-crested weir and ensures a constant discharge coefficient for all heads.
The discharge passing over an ogee spillway is given by (where, L is effective length of spillway crest and H is the total head over the spillway crest including velocity head.)