Re-considering reason of serious scour produced in Kariba Dam

Scour depth in Kariba Dam reaches 57 [similar to] 80 m. This is the most serious one in the world. There are many reasons in the aspects of the geology and the arrangement of the outlets. The primary causes generating scour are that the Froude numbers of releasing outlets are relatively low, the energy of 6 nappes entering downstream water body is highly concentrated, meanwhile, there was no any bed protection measure. Summing-up the experience can avoid the similar serious scours in China. This is significant for demonstrating the feasibility of water cushion pool without bottom lining but with protecting both bank slopes in Xiaowan and Xiluodu Projects. And it can be also used as a reference for other water projects.