The EcoPeak4Fish project: an integrated approach to support self-sustaining fish populations downstream hydropower plants

The need to increase hydropower production to reduce CO2 emissions, while supporting the development of self-sustainable fish populations in a cost-effective way, protect biodiversity and restore water-related ecosystems is urgent and recognized in the UN Agenda 2030 and in the recently launched European Green Deal. Despite the growing awareness of hydropeaking impacts, it is still largely unknown how fish react under peak events, especially cyprinids, the most common group of freshwater fish in Europe. Flow-refuges such as lateral deflectors are believed to help fish to cope with rapidly changing flows and high currents. However, very few studies assessed their efficiency and focused mainly in salmonid species, with higher economic value. Although recent studies have assessed the utility of flow-refuges for cyprinids in controlled experimental conditions, field evidence of fish responses to hydropeaking and the use of flow-refuges in peaking rivers remains, to our knowledge, unknown. Another option is adapting the hydropower operation scheme to improve fish habitat during daily cycle or during important key life-cycle stages (e.g. spawning). These measures may have a significant impact on the HPP profits thus affecting its viability. Including habitat in models of HPP optimal management is usually done by means of adding restrictions regarding minimum flows. The feedbacks between available habitat and profit are not explicitly modelled. Including a description of how the available habitat changes with water flow can help estimate trade-offs between profit maximization and habitat preservation as well as inform the development of flow restrictions that better account for both profit and habitat availability. The EcoPeak4Fish project, recently started, intends to answer these questions in a multidisciplinary approach. Thus, EcoPeak4Fish stands in 4E's: Ecology, Engineering and Economics in the profit of the Ecosystem protection. This project aims to assess the effects of hydropeaking in cyprinid species, propose a flow-refuge prototype and assess its cost-effectiveness, and develop a framework to adapt the HPP operation scheme to maximize profits and environmental benefits for a sustainable use of hydropower energy. The project intends to answer the following questions: How do fish react under hydropeaking conditions? Are flow-refuges an effective measure to mitigate impacts and contribute to the self-sustainability of fish populations? How to find the hydropower operation scheme that maximizes profits and power production while maximizing the suitable habitat for fish populations? The project structure and expected outputs will be presented, as well the first results concerning the different tasks of the project and implications for management..