Rehabilitation of Vertical Slot Fish Pass with the Installation of Brush Blocks and Substrate: A Pilot Project in Cataloluk Small Hydropower Plant, Turkey

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 beside the main brush block. The prototype results from this study would be useful to both fish-pass designers and fish biologists.