Effect of using stepped gabions on the distance of the hydraulic jump

Abstract

The present study investigates the effect of using stepped gabion weir in a laboratory channel on the distance of the hydraulic jump. A set of 25 laboratory experiments and 175 operation tests were conducted using a laboratory flume with dimensions 10 m long by 0.3 m wide, and 0.5 m high. The tested gabion weir had different five possible lengths 0.88 m, 0.96 m, 1.04m, 1.12 m, and 1.20 m, and the filling material used was natural quarry mono graded gravel in five different sample sizes of average equivalent diameter 11.75 mm, 16.50 mm, 22.00 mm, 31.25 mm, and 43.75 mm. Operation discharge values ranged between 0.7 to 15.0 l/s. The data set was subject to dimensional analysis to generate dimensionless groups, and correlated using the Buckingham Pi-Theorem. The results of this study showed that in case of direct representation between the parameters, the distance of hydraulic jump has a direct relationship with discharge but both the gravel sample used and the overall length of the weir give an undular behaviour with its increment. While using of dimensional representation shows that both the gravel sample and weir length have an inverse relationship with the distance of the hydraulic jump. Many trials have been made to formulate the best equation which combine the studied parameters with good agreement.