Investigation on the effect of different parameters on maximum scour depth at triangular labyrinth weir without apron

We studied downstream scour at the triangular labyrinth spillway. In this study, we used labyrinth spillway with 6 different angles (150, 300,450, 67.50, Linear) and seven ratios (H/P=0.1-0.7 ). In this experiments the effect of H/P, Froude number and cycle angle on scour depth and hole dimensions were investigated. The results indicated that H/P, Froude number and cycle angle had a significant effect on scour depth and hole dimensions. When H/P increased 7 times, scour depth increased 12 times and scour length 10 times. Furthermore, whit increasing cycle angle 6 times, scour depth decreased 70%. There is no reasonable relationship between hydraulically parameters and the maximum height of sediment mound. Finally, with analyzing data and the results of experiments, we presented some empirical formulas for estimating of scour-hole dimensions.