Form drag resistance of two-dimensional stepped steep open channels

Abstract

Flow in rough steep open channels is mostly found in mountain streams and in flow overtopping protected weirs. In both cases, the energy of the flowing stream may be dissipated by artificial means so that the flowing water does not result in serious damage due to scour or erosion downstream of the main slope. The best way of achieving this purpose is to lead the flow over a series of steps. In this investigation, the author tried to determine the form drag of stepped steep open channels, considering the steps as two-dimensional triangular roughness elements. Key words: open channel flow, flow resistance, channel roughness, form drag, steep channels.