This spillway is suitable for earth or rock fill dams, in narrow canyons and other situations.
This spillway is also the best choice where a long overflow crest is require so as to limit the surcharge head and also under the situation where abutments are steep and precipitous.
In this spillway the control weir is kept along the side.
The flow after passing over the crest turns at approximately 90°.
Flow may enter the side channel from one side only or from both the sides and one end also.
Discharge characteristics are similar to ordinary overflow weir, except that at high discharge its crest may be partly submerged.
Generally a trough is formed on D/S side of the crest and water enters it before taking a turn to flow in the side channel.
