Two New Equations for Energy Dissipation down a Stepped Spillway with Channel Slopes between 3.4° and 26.6°

A stepped spillway is a hydraulic structure provided at storage and detention dams to release flood water that cannot be retained safely in reservoirs. Its purpose is to increase the energy dissipation that would have caused dangerous scour in the natural channel below the hydraulic structure. Several studies in the literature highlight the destructive effects of the kinetic energy of water falling on the nature water channel. However, only a few of these studies considered the impact of energy losses resulting from stepped spillways with channel slopes of 3.4
and 26.6
. Additionally, the existing model for predicting energy dissipation in stepped spillways features a parameter, the friction factor, f, which is difficult to estimate with certainty, thereby giving rise to its subjective estimation by those involved with the design of stepped spillways. The authors resolve these issues by reviewing researchers' publications on horizontal stepped spillways with dam slopes between 3.4



26.6
conducted in transition and skimming flows in large-size facilities with phase-detection intrusive probes. They obtain data sets from them, which they reanalyzed to develop two new energy dissipation models without the parameter, f (the frictional factor) that govern transition and skimming flows over a wide range of operating conditions. The data sets from these new models compare favourably with the measured data sets, with coefficients of correlation ranging from 0.95 to 0.99. These models are simple to use and produce more accurate results than the current model.