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Pilot Project CBR Fish Guiding Rack HPP Herrentöbeli

Researchers from the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) at ETH Zurich, together with Wälli AG Ingenieure and the hydraulic steel constructor Fäh AG, developed a new, innovative fish guide rake for the best possible protection of animals passing through power plant facilities during downstream migration.

All fish migrate

Fish depend on being able to migrate freely (e.g. to spawn, to search for food, to escape, etc.), but this is made difficult in many places by power plants. The Water Protection Act, in force since 2011, prescribes measures to restore fish migration in Swiss rivers. Fish ladders have been used for years for upstream passage, but downstream migration still poses a problem for many fish.

Renovation of the Herrentöbeli hydroelectric plant — Fig. 1: Renovation of the Herrentöbeli hydropower plant near Krummenau on the Thur with a new type of fish guidance bypass system in spring 2022. Wälli AG

Promising new type of fish guide rack

The newly developed and patent-pending fish guide rack is currently being installed for the first time on a prototype scale in combination with a fish bypass channel at the Herrentöbeli small hydropower plant on the Thur in Toggenburg (see Fig. 1). The power plant is operated by St. Gallisch-Appenzellische Kraftwerke AG (SAK) and is being converted as part of the ecological rehabilitation of hydropower plants to meet the objectives of the Water Protection Act. The system has already been tested extensively in the VAW laboratory (Fig. 2) - including fish tests - as well as by means of hydrodynamic numerical simulations and is now to be tested for its practical suitability under real conditions.

Fig. 2: Ethohydraulic test channel in the VAW laboratory with a new type of CBR fish guidance rack. VAW, ETH Zürich

Pilot phase

The pilot project is financially supported by the Federal Office for the Environment (FOEN) in order to gain experience with the new fish guidance bypass system. After commissioning, extensive hydraulic and fish biological monitoring campaigns will be carried out to investigate the effectiveness of the system on fish protection and fish routing during downstream migration and to compare it with the results of fish tests in the laboratory.

Further information can be found on the external page project website of SAK.

Nomination for the Spark Award: Top 20!

The fish guide rack developed in collaboration with Walli AG Ingenieure and Fäh AG has been selected as one of the top 20 technologies of 2021. ETH Zurich presents the Spark Award for the most promising invention that has led to a patent application in the last year. The criteria for the evaluation are originality, patent strength and market potential.

Other media presence

Broadcast in Tele Ostschweiz, 17.5.2022 - external page Lebensretter im Toggenburg: Neuer Fischleitrechen schützt Fische vor Todesturbine