Enhancing Hydraulic Efficiency in Denil Fishway: Impact of Baffle Configurations on Flow Characteristics

The fragmentation of river networks by man-made barriers such as dams has a significant impact on fish populations as it disrupts migration and habitat connectivity. This study aims to improve the hydraulic efficiency of Denil fishways by investigating the influence of different shapes of baffles (i.e., triangular, semicircular, and rectangular) on hydrodynamic parameters. Using computational fluid dynamics (CFD) simulations, we evaluated the performance of the modified guardrail configurations. The numerical model was validated by comparing computed flow depth (h_u) and discharge coefficient (C_d) with those measured experimentally from the literature. The study showed that the modified baffles significantly affected the flow characteristics. The rectangular baffles reduced the flow depth by up to 25.8% and increased the C_d value by 75.7% compared to the standard triangular baffles. In addition, the rectangular baffle design was characterized by the creation of a low-velocity zone, which is crucial for fish passage, especially for smaller species. These results suggest that modified guardrail shapes can improve the hydraulic efficiency of Denil fishways, providing a potential solution to improve fish migration through fragmented river systems.