Experiments in Side‐Channel Spillways

Results of experimental observations in rectangular side‐channel spillways are presented, with particular attention to the effects of a nonprismatic cross section and the bottom slope on the free surface profile. For subcritical flow, the difference of surface profiles along the channel axis and the side walls is outlined. Further, flow configurations with supercritical inflow conditions and the possible formation of hydraulic jumps along the lateral inflow length are discussed. The observations are compared with predictions based on an extended theoretical approach, thereby including the streamwise momentum contribution due to the lateral flow. The agreement between the computed and the observed axial free surface profile is fair. The proposed extended model equation should be considered whenever the bottom slope of the side channel is larger than a certain percentage.