Effects of slope and step size on the hydraulics of stepped chutes : technical paper

Stepped spillways and chutes provide an effective means of dissipating energy in the release of flood water from impoundments. Their performance depends on whether flow is of the nappe or skimming type, and on the step geometry. Prediction of the flow type and energy dissipation performance is based on experimental results from model and prototype tests. This paper presents the results of an experimental investigation of the transition between nappe and skimming flow and energy dissipation for a wide range of flow conditions and step geometries. Previously proposed methods for predicting the transition conditions and nappe flow energy dissipation are shown to be inadequate for some conditions, and provisional new formulations are presented.