Hydrodynamics model aims to improve fishways for all fish

Around the world, tens of thousands of dams, weirs, and culverts fragment rivers and block fish migration routes, posing serious threats to aquatic biodiversity. Although many fish passages have been engineered to bypass these barriers, they are often either hydraulically inefficient or biologically unsuitable for many species.

To address this, Sellila et al. developed a “virtual fishway” — a computational model designed to analyze water flow dynamics in vertical slot fishways. By combining the renormalization group turbulence model with the Darcy–Forchheimer approach to account for flow resistance, the researchers simulated complex hydrodynamic features such as vortices, jets, and swirls. Their model provides a fast, efficient way to evaluate how fishways perform under realistic flow conditions.

“We are really excited by the methods and results because they show a way to make infrastructure compatible with living ecosystems, giving fish a fighting chance to survive and ensuring that biodiversity is not just an afterthought but a design principle,” said author Waleed Mouhali. “This opens the door to systematically testing and optimizing fishway designs, ensuring they are not only functional for water passage but also truly effective for fish migration.”

Next, the team plans to integrate models of fish behavior to better understand how specific species interact with the flow conditions. They also aim to explore nature-based solutions inspired by natural river features.

“We hope this research will guide engineers and ecologists in designing fishways that balance hydraulic efficiency with ecological functionality,” Mouhali said. “Applied widely, these tools could help restore connectivity in river systems, improve biodiversity preservation, and make human infrastructure more sustainable.”

Source: “Numerical investigation of fishway hydrodynamics using the renormalization group turbulence model and Darcy–Forchheimer flow resistance,” by Nacer Sellila, Waleed Mouhali, Mohammed Louaked, and Houari Mechkour, Physics of Fluids (2025). The article can be accessed at https://doi.org/10.1063/10.0039494 .