Hydraulics of flow in gabion stepped spillways, an experimental study

In this study, the effect of different hydraulic parameters on the energy loss of flow over gabion stepped spillways are examined using physical models and comparisons are made with the other studies. Two end sills including rectangular and inclined shapes are used on each spillway step. The results showed that the influence of end sills in gabion stepped spillways with lower slopes is greater than that of spillways with higher slopes. The influence of end sills on energy loss in spillways with d50=40 mm and S = 1:2 is about 10% more than the spillways with d50=10 mm and S = 1:1 (d50 is the mean diameter of gravel in the gabion and S is the downstream slope of the gabion stepped spillways, vertical: horizontal). Energy dissipation in spillways with d50=10 mm and S = 1:2 is about 30 to 35 percent more than spillways with d50=10 mm and S = 1:1. Hence, end sills in spillways with gravel size of d50 = 10 mm have the most significant impact on the energy loss. Instead, the influence of the rectangular end sill on the energy loss is about 3-4% more than the effect of a triangular (inclined) end sill.