Author(s): Serhat Kucukali; Ahmet Alp; Adil Akyuz

Linked Author(s): Serhat Kucukali

Keywords: Vertical Slot Fish Pass; Rehabilitation; Flexible hydraulic elements; Micro-habitat; Turbulence

Abstract: The fish passage performance and flow structure of a vertical slot fish pass, with and without brush blocks, were investigated at the Cataloluk Small Hydropower Plant on the Tekir River, located in the Ceyhan River Basin of Turkey. Within the scope of the project, three-dimensional velocity measurements and fish monitoring studies were performed for different hydraulic conditions. The prototype flow measurements showed that by placing brush blocks and substrate in a vertical-slot pool: (i) the maximum velocity observed near the bed at the downstream of the slot was reduced by 50%, (ii) the flow energy is effectively dissipated by the vibrations and bending of the bristles leading an about 16% reduction in the spatially averaged turbulence kinetic energy and spatially averaged power velocity is reduced by 20%, (iii) turbulent jet region reduced and recirculation regions disappeared, (iv) behind the brush blocks resting areas are created for fish and new migrations corridors are created besides the main brush block. By processing underwater video recordings, it has been shown that micro-habitat is created for fish after the installation of brush blocks and substrate. In addition, the passage efficiency of the vertical slot fish pass was assessed using Passive Integrated Transponder (PIT) telemetry method. After the installation of brush blocks and substrate, the upstream passage of efficiency of Capoeta damascina increased from 15.4% to 66.1%. The passage efficiency of Alburnus adanensis was found as 52%. These efficiency values of the fish pass are higher than those of other technical type fish passages presented in the literature for a fish pass with a variable bed slope of 7-10%. Also, the data revealed that the structural modification provides passage for small-bodied fish in a high-gradient channel. The monitoring data revealed that polypropylene bristles, which have modulus of elasticity=1.45 GPa and density=905 kg/m3, as flexible hydraulic elements and energy absorbers are beneficial for migrating fish. The proposed innovative design has been found to be cost-efficient and easy to implement in existing vertical slotted fish passages. The investment cost is about 15,000 EUR and installation was completed in one week. The results obtained from this study are expected to contribute to the rehabilitation projects of fish pass structures considering the ecological conditions in the project area.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022666

Year: 2022