» Research Note « Increasing the Discharge Capacity of an Ogee Spillway by Bending the Crest

Document Type : Technical Note


1 M.Sc., Water Engineering, Water Research Institute (WRI) , Tehran, Iran.

2 Professor, Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran.

3 B.Sc., Water Engineering, Water Research Institute (WRI) , Tehran, Iran.


The effective length of spillway is an important factor in increasing its discharge capacity and consequently decreasing the head over the spillway crest and the dam height. On the other hand, increasing the straight crest length increases the chute width and volume of excavations. Increasing the effective length of the spillway in a limited width is a method to reduce the construction costs. Curved crest spillway is an example of such methods. In the present work, discharge coefficient of a curved crest ogee spillway is compared with a straight one, both with the same chute width in a physical model.  Results showed that the discharge coefficient of the curved ogee crest is similar to the straight one. Therefore, discharge capacity of the curved ogee was more than the straight one due to its longer length. Based on the results of the present work, designers can increase the discharge capacity of ogee spillways by bending them in a constant chute width. It should be noticed that the transition between the curved ogee and the chute and also the upstream guide walls should be designed so that these transitions make no disturbance and shockwave.


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