ABSTRACT
A culvert structure typically incorporates an inlet, a barrel, and an outlet. Considering a box culvert with invert set at ground level and built in a flood plain with a mild slope, the culvert operation at less-than-design flows would include a relatively smooth flow convergence into the inlet leading to the barrel entrance. In some cases, a lower invert may allow to retain a pool of water in the culvert barrel during dry to very low-flow conditions. During the lifespan of a culvert, regular inspections and maintenance must be undertaken. A range of wall boundary treatments and appurtenances were tested with the aim being to improve the upstream passage of small fish in the culvert barrel, focusing on boundary conditions that have a minor impact on the discharge capacity of the culvert at design discharge. The interpretation of the turbulence typology is critical to any successful boundary treatment conducive to the upstream passage of small-bodied, weak-swimming fish.
