Author(s): Anita Moldenhauer-Roth; Oliver M. Selz; Ismail Albayrak; Robert M. Boes

Linked Author(s): Ismail Albayrak, Robert Boes

Keywords: Fish downstream movement; Fish protection; Electrified rack; European eel; Cyprinids

Abstract: Turbine passage of downstream moving fish can result in injuries and mortality. Due to their body shape, European eels are particularly prone to injuries caused by turbine blades. Physical and mechanical behavioral fish guidance structures that are typically recommended to guide fish to a safe bypass route are often not suitable for large hydropower plants (HPP) due to their considerable length. Retrofitting trash racks with electricity can be a promising approach to increase fish protection in such cases. In the present study, a 1:1 model of a typical trash rack with a bar spacing of 90 mm was electrified using the rack as an electrode and placing an additional row of electrodes 142 mm downstream. The systematically applied electric voltage was 44 V and the electric field was numerically simulated. Live fish tests were conducted with Brown trout (Salmo trutta), Chub (Squalius cephalus) and European eel (Anguilla anguilla) in an experimental flume. Without electrification, the rack has no fish protection effect. For chub, the fish protection efficiency (FPE) of the electrified rack was 78% at an approach flow velocity of 0.15 m/s and 95% at 0.6 m/s. For eel, the FPE was 92% at 0.3 m/s and 76% at 0.6 m/s. For trout, no avoidance reaction to the electric field was observed and tests were abandoned after a total of six trout had passed the rack. Given the high FPE for eel and cyprinids, this setup presents a promising solution to reduce turbine passages at large HPP for these species.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0512-cd

Year: 2023