Modelling low velocity zones in box culverts to assist fish passage

A culvert is a covered channel designed to pass water through an embankment. The recognition of the adverse ecological impacts of culverts on upstream fish passage is driving the development of new culvert design guidelines, with a focus on small-bodied fish species seeking low velocity zones (LVZs) to minimise energy expenditure. Herein a hybrid modelling technique was applied, combining physical modelling, onedimensional numerical modelling and three-dimensional computational fluid dynamics modelling (3D CFD). The results reveal fundamental turbulent processes that may affect small fish navigability and provide new insights for the development of standard box culvert design guidelines