Author(s): Martin Bombac; Gasper Rak

Linked Author(s): Martin Bombac, GAŠPER RAK

Keywords: Numerical modelling; Vertical slot fishway; Turbulence; Velocity field; Turbulent kinetic energy dissipation

Abstract: River dams disrupt fish migration, necessitating the implementation of effective mitigation measures, such as vertical slot fishways (VSF). This study applies a two-dimensional model to simulate flow characteristics in a VSF and validates the results with field data from the Arto-Blanca hydropower plant on the Sava River, Slovenia. The model, using a depth -averaged k–ε turbulence scheme, accurately reproduced measured velocity fields, confirming its suitability for hydraulic analysis and design. Sensitivity tests revealed that grid resolution and turbulence modelling have a significant impact on accuracy, whereas bottom roughness has a negligible effect. Simulations for varying slopes revealed that steeper gradients significantly increase velocity and turbulence beyond biological limits. The results highlight the value of numerical modelling for optimising fishway performance and ensuring ecological connectivity in regulated rivers.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.172

Year: 2026