Asymmetrical Wall Baffles to Assist Upstream Fish Passage in Box Culvert: Physical Modeling

Abstract

Although waterway connectivity is a requirement for all freshwater fish, culverts have had negative impacts on freshwater river ecology. Following a recent biological study suggesting that asymmetrical wall baffles may be conducive to upstream passage of small-bodied fish, experimental modeling of plain wall baffles on one sidewall only was conducted under controlled flow conditions. The measurements were performed in a 15-m-long, 0.5-m-wide culvert barrel channel at several longitudinal and transverse locations for a broad range of discharges and baffle geometries to deliver a fine characterization of the hydrodynamics of the asymmetrically baffled channel. The physical modeling data illustrated the drastic impact of a seemingly simple boundary treatment (i.e., plain rectangular baffles) on the flow field. In practice, the installation of baffles has practical engineering implications that must not be ignored.