Thesis Work – From flow to fish: Hydraulic characterization of a new fish swimming flume

To comply with the European Water Framework Directive, Sweden is currently undergoing a large-scale hydropower relicensing process under the National Plan for Modern Environmental Conditions for Hydropower (NAP) aimed at reducing the environmental impacts of hydropower production while maintaining renewable energy generation. A key challenge is the restoration of river connectivity through the implementation of effective upstream and downstream fish passage solutions. However, designing solutions that accommodate a wide range of fish species and swimming abilities requires a detailed understanding of how fish respond to hydraulic conditions such as velocity and turbulence.

To support this need, Vattenfall R&D is commissioning a new state-of-the-art flume that allows controlled investigations of fish swimming performance and behaviour under varying hydraulic and environmental conditions. Before biological experiments can be conducted, the hydraulic characteristics of the facility must be thoroughly quantified using experimental flow measurement techniques such as Acoustic Doppler Velocimetry (ADV) and Particle Image Velocimetry (PIV). The results will provide the hydraulic foundation for future research linking flow conditions to fish behaviour and swimming capacity, ultimately contributing to more effective and evidence-based fishway and bypass design.