LOCATION OF AIR INCEPTION POINT FOR DIFFERENT CONFIGURATIONS OF STEPPED SPILLWAYS

Twelve stepped spillway models have been manufactured with three downstream slope angles: 25, 35 and 45°, and four numbers of steps: 5, 10, 15 and 20. The results of experimental work emphasize that for the same model air inception point location moved downstream as the discharge increased. For the same discharge, the location of air inception point was closer to the crest for larger step heights and lesser slope angle. The location o f air inception point was closer to the crest in pooled steps compared with flat steps; this location was farther than flat steps when the gaps between end sills and step rises were filled with gabions.