Minimizing Scour of Contraction Stepped Spillways

The scour downstream spillways can endanger the stability of the dams. Hence, determining the scour depth downstream of spillways was vital importance which scours holes formed around and near the foundations of spillways can endanger the stability of dams and may lead to their failure. So, this paper, investigate the scour downstream contraction stepped spillways. The experimental flume used 16.2 m length, 66 cm width and 65 cm depth. The used number of stepped spillways was 4 Sep, contraction ratio was 60% from flume width and the opening area in breaker 10% from the breaker area on all sides putting in down of breakers. The breaker used above the stepped spillway with different shapes of openings as rectangle, triangle and trapezoidal and different numbers by 2, 4, 6 and 8 of beakers. The divergent angle changes by 45º, 30º, 15ºand 10º. The results were showed that the best numbers of openings is 4openings with rectangle shape because it reduces the scour by 54.51%. In finally to improve this scour by divergent angle lead to the best angle is 10º can minimize the scour is 65.38%.