Effects of End Sill and Step Slope on Stepped Spillway Energy Dissipation

Document Type: Original Article


1 Department of Technical and Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran

2 Civil Engineering Department, Islamic Azad University, South Tehran Branch, Tehran, Iran


In this study, experimental procedure and laboratory works have been conducted to investigate the energy loss rate on stepped spillway, using inclined steps together with end sill. To have a more elucidated investigation inclined steps with different slopes (Horizontal , 7, 10, and 12 degrees with respect to the horizon) and end sill with different thicknesses (5 and 10 mm) and heights (6, 8, 10, and 15 mm) were used to determine the impact of these parameters on the relative energy loss. Results show that using inclined steps together with end sill has a considerable effect on the energy loss of both nappe (30 liter/sec) and skimming (90 liter/sec) flows; however, energy dissipation in nappe flows is greater than that in skimming flows. Energy loss resulted from end sills with smaller thicknesses is higher than that of end sills with greater thicknesses. Comparison of the results of the current survey with similar studies reveals that the approach used in the current investigation is more efficient than previous ones.