Alleviation the scouring problem downstream of dam spillways through a reversed cross-jet flow dissipator

In this paper, a reversed cross-jet flow is developed to dissipate the energy of flow over an ogee weir spillway. The problem is handled analytically and experimentally. Both measured and calculated data indicate a great effect on the forced hydraulic jump characteristics compared to those describing the characteristics of the free jump condition. The obtained results revealed that, the reversed flow, can speed up the transition from supercritical to subcritical flow by creating a forced perfect jump starting at the contracted section and consequently, shortening the protection length needed to counter the problem of scouring downstream of the channel, since the length of the perfect hydraulic jump was reduced by 19%, while reduction in the length of the stilling basin amounted to 79%, in comparison to the case without a dissipator. The efficiency of such energy dissipation methods can have a significant impact on the overall cost of hydraulic structures projects.