Author(s): Sameh Kantoush; Hossein Sohrabzadeh-Anzani; Sohei Kobayashi

Linked Author(s): SAMEH KANTOUSH

Keywords: Bed Configuration; Open Channel Flow; Fishway; Flow Dynamics; Turbulence

Abstract: Hydraulic structures in rivers often impede fish migration due to high velocities and turbulence. This study investigates the hydraulic effects of bed roughness configurations, smooth bed, one-sided wart-type baffles, and both-sided wart-type roughness on flow velocity, turbulence intensity, and velocity deficits in a 0.5 m × 7 m flume with 2% slope at Ujigawa Hydraulic Laboratory, Kyoto University. Velocity measurements were conducted using an electromagnetic flowmeter at five longitudinal stations. Results show that the smooth bed yields the highest depth-averaged velocity (1.15 m/s) with minimal turbulence intensity (TI ≈ 0.01). One-sided roughness reduces mean velocity to 0.85 m/s, introducing moderate TI (0.009–0.012) and asymmetric low- velocity zones. Both-sided roughness further lowers velocity to 0.6 m/s, enhancing TI (0.010–0.012) and pronounced velocity deficits, creating extensive resting refuges but risking excessive turbulence. One-sided roughness provides the optimal balance for fish passage, minimizing energy barriers while ensuring connectivity.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.120

Year: 2026