Abstract
Stepped spillways are used to improve the hydraulic performance of a water-flow structure. This research describes the study of two types of physical models to investigate the impacts of rough steps on stepped spillways in terms of energy dissipation and hydraulic jumps. To this end, six stepped spillway models, including a flat spillway with smooth steps and five models with rough steps using gravel with a given grain size (i.e., d50 = 18.9 mm), were made with different step arrangements. The results showed that stepped spillways with rough steps and in the nappe flow regime show a better performance regarding energy dissipation of about 20.97 % compared to smooth steps. On the smooth stepped spillway, the non-dimensional residual head was 4.65, and for similar operating conditions, the average dimensionless residual head on the rough steps was 2.92. Furthermore, when rough steps are placed on all steps, the hydraulic jump characteristics, including sequent depth ratio, jump length, and roller length, decrease by 3.34, 8.61, and 8.14 %, respectively, compared to smooth steps.
•Investigation of the hydraulic jump characteristics and energy dissipation using rough steps on stepped spillway.•The reduction in jump characteristics and increase in energy dissipation depends on the arrangement of the rough steps.•The reduction of the relative jump length and roller length in the rough steps was calculated as 31.13% and 35.54%.•Rough steps on stepped spillways increased the energy dissipation by 20.97 % compared to smooth steps.