Author(s): Mehmet Salih Turker; Serhat Kucukali

Linked Author(s): Serhat Kucukali

Keywords: Pool-weir fishway; Turbulence; Flexible hydraulic element; Low-velocity zone

Abstract: This study aims to create alternative migration corridors and increase the efficiency of the pool-weir fish pass. For this purpose, the hydrodynamic and fish migration characteristics at a pool-weir fishway were monitored and evaluated simultaneously at the Dagdelen Small Hydropower plant in Ceyhan River Basin, Turkey. The performance of flexible cylindrical hydraulic elements, a cost-effective method to create resting areas and dampen macro-turbulence, was tested at a prototype scale. 3D velocity measurements were conducted in the fishway pool using a Micro acoustic Doppler velocimeter under real-time operation conditions. The measurements were taken with and without bristles at two different elevations. The spatial distributions of velocity vectors and Reynolds shear stress were presented for two different hydraulic conditions. It is depicted that in the existing structure a turbulent wall jet, which is associated with high velocities and turbulent fluctuations, recirculates around the pool. Besides, the flow behind the brushes is characterized by a low-velocity zone where fish are not subject to considerable turbulent shear forces which constitute important resting sites for fish. Underwater video recordings showed that fish seeking low-velocity zones pass through the hydraulic structure. The monitoring data revealed that bristles as flexible hydraulic elements are beneficial for migrating fish. The bristles as energy absorbers represent a cost-effective option, which can be retrofitted at any time existing structures, to improve the hydraulic conditions and dampen the turbulence in fishways. The findings are important for the rehabilitation works to be carried out to establish or increase the continuity of the migration route in the existing fishways.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0260-cd

Year: 2023