Fish downstream passage at hydropower plants remains a relatively unresolved environmental issue. A number of investigations have shown, that fish injury and mortality due to turbine passage can have significant magnitude and respective ecological impact. Actual values depend largely on the underlying facility and fish population. While remarkable scientific progress has been achieved during the last decades, a broad application of this knowledge has not emerged yet. The EU-Horizon 2020 project FIThydro, addresses the decision support in commissioning and operating hydropower plants (HPP) by use of existing and innovative technologies. It concentrates on mitigation measures and strategies to develop cost-efficient environmental solutions and on strategies to avoid individual fish damage and enhancing population developments. Consequently, fish turbine passage issues are considered beside other aspects. The respective work focuses on the assessment of damage rates and moreover on their mitigation. Broad literature research provided a variety of approaches to assess fish damage due to turbine passage on experimental, empirical or theoretical based methods. The individual applicability and suitability have been benchmarked. Equally, the research results provide insight to particular fish passage aspects of different turbine types. Beside classical designs, this also accounts for innovative schemes and especially those seeking favourable fish passage conditions. Diverging existing modelling approaches for damage rates during turbine passage have been analysed in detail, to clarify differences and correctness. Based on the literature research and analytical and statistical modelling, a generalized modelling of fish damage due to turbine passage could be deduced. The model allows for consideration of detailed fish passage conditions, e.g. with regard to fish comportment as well as turbine service condition. Recent research findings for fish stress response to respective load have been included. Model development was facilitated by vast numerical modelling of turbine passage conditions by project partners, which moreover developed an CFD based fish stress assessment capable of taking into account detailed hydrodynamic conditions. Moreover, project partners conducted sensor fish passage investigations at several hydropower plants to provide a comprehensive set of experimental data for model development and evaluation. The enhanced modelling can provide improved fish damage assessment. Furthermore, the better understanding of fish damage sources allows for targeted mitigation measures with regard to turbine design and service. A number of experimental investigations, including live fish behaviour studies, were conducted to clarify the influence of fish comportment during turbine passage on the resulting damage rates. These works also emerged the development of an innovative technology, which intends to reduce fish damage during turbine passage by the manipulation of fish comportment. This could provide an especially cost-efficient solution to achieve ecologically compatible fish passage conditions.     «

Fish downstream passage at hydropower plants remains a relatively unresolved environmental issue. A number of investigations have shown, that fish injury and mortality due to turbine passage can have significant magnitude and respective ecological impact. Actual values depend largely on the underlying facility and fish population. While remarkable scientific progress has been achieved during the last decades, a broad application of this knowledge has not emerged yet. The EU-Horizon 2020 pro...     »