Simple Methods for Energy Dissipation at Culvert Outlets

Abstract

Experiments were performed to investigate the energy dissipation realized at the outlet of a culvert using two simple design alternatives: (1) Design I, a simple weir near the culvert outlet, and (2) Design II, a weir with a drop upstream in the culvert outlet barrel. The two designs are intended to reduce the flow energy at the outlet by inducing a hydraulic jump within the culvert barrel, without the aid of tailwater. This paper examines the jump geometry, the effectiveness of each jump type, and proposes a design procedure for practicing engineers. The design procedure is applicable to culverts with approach Froude numbers from 2.6–6.0. Both designs are effective in reducing outlet velocity 0.7 to 8.5 ft/s (0.21–2.59 m/s), momentum 10–48%, and energy 6–71%. The design layouts allow easy access for maintenance activities.