The FIThydro – Fishfriendly Innovative Technologies for hydropower was created in 2016 and aimed to improve the ecology of rivers affected by hydropower exploitation, namely fish population- and also to improve the existing technologies and devices to assess the fish behaviour in the presence of obstacles associated with these exploitations, and to facilitate their migration along the affected rivers. Thirteen research institutions, including CERIS, and thirteen companies have worked together to achieve these goals over the last 4 years. Now that the project has ended (October 2020), the final balance is very positive. Both the results and the progress made are quite significant. The contributions of CERIS-Civil Engineering Research and Innovation for Sustainability research team, led by professor António Pinheiro, played a key role during the various stages.

The FIThydro project was funded by the Horizon 2020 programme (€7,2 million) and studied the impact of hydropower exploitation on river ecosystems, in particular on the fish fauna, in 17 case studies spread over eight countries. Through these studies, it was intended to identify and fill knowledge gaps, to understand how existing tools could be improved, and to develop new mitigating solutions. The Técnico team carried out one of these case studies and the results were published in PLoS ONE Journal.

This study was carried out in an experimental channel at the Hydraulics Laboratory – Técnico (LHIST) and aimed to simulate the rapid changes in flow that occur in rivers downstream of hydroelectric power plants. According to researcher Isabel Boavida “it is important to understand the effects of changes in flow rates, in different locations, on fish behaviour”. “To this end, tests were carried out to check whether the fish population used the structures installed in the channel to escape from the high flows, just as they would in rivers using the stones as a shelter”, adds the researcher.

Through a probe developed by researchers at Tallinn University of Technology, whose shape resembles that of a fish and that mimics the lateral sensory line of the fish, it was possible to measure the pressure gradients induced by the flow, similarly to what should be perceived by the fish. By characterizing the fluid–body interaction, it is possible to simulate the flow pattern to which the fish would be subject under natural conditions.

“Relating responses to stress and mobility behaviours with specific changes in flow rates allowed us to establish a cause-effect relationship between these changes and behavioural changes”, explains Dr Maria João Costa, LHIST researcher, in the statement sent by the FIThydro consortium. The laboratory results were transferred to another case study, at the Bragado hydropower plant, in collaboration with Hidroerg – Projetos Energéticos Lda, which is part of the project consortium. Using a telemetry system installed downstream of this plant, the researchers tested the impact of flow variations on fish movement and habitat.

The CERIS team worked together once more with Hidroerg to analyze the public perception of the EU on hydropower exploitation. To this end, surveys were carried out in Vila Real municipality and in different regions of France, Germany and Sweden. According to Pedro Eira Leitão, manager of Hidroerg, “the study showed that opinions about run-of-river hydropower are not homogeneous, varying according to the type of region (there are more similarities between Sweden and Germany than between those two countries and France, Portugal) and according to respondents’ age”.

Professor António Pinheiro stresses “most of the respondents in Portugal had an opinion on various aspects related to hydropower production in run-of-river plants. Nevertheless, some of the answers showed gaps in knowledge on this topic, namely the way hydropower production is processed and regulated in Portugal”.

One the main conclusions drawn by CERIS research team was that “the Portuguese public perception of hydropower production is polarized among people with a generally positive opinion, which is associated with the contribution of hydropower to the mitigation of climate change and local / regional development, and people with a critical position, who highlight the large-scale impacts of hydropower on natural ecosystems and on agricultural and forestry activities”, explains professor António Pinheiro.

Decision support tools designed at Técnico

The second stage of the project explored possible measures for the retrofitting of hydropower plants, such as more fish-friendly turbines, as well as decision support tools designed to help operators and those responsible for planning hydropower exploitations.

In order to assess the hydropeaking impacts and to identify appropriate mitigation measures, CERIS scientists, together with researchers from SINTEF (Norway) and SJE (Germany), have developed and adapted a hydropeaking tool that was designed to assess the impacts of hydropeaking on fish populations in regulated rivers.

“The tool was initially developed in Norway for salmon. We adapted the same tool to the most common species in the Iberian rivers and in the center of Europe”, says Dr Isabel Boavida, who was in charge of the tool development at CERIS. It helps to analyze, above all, the impact of a hydropower plant on the fish population, taking into account the vulnerability of the water course and the operation of a hydropower plant. “The tool is very useful to assess the impact of a hydropower plant operating in hydropeaking regime on the riverside ecosystem, also allowing to evaluate the effects of the mitigation measures to be proposed, where appropriate”, she adds.

FIThydro Decision Support System is one of the main outcomes of the project. By entering data related to types of exploitation, location, fish populations in the water courses, etc., the user will be able to understand the level of environmental risk and the danger for the fish populations. In addition, the system also provides recommendations regarding the mitigation measures to be adopted.

The negative impacts of hydropower production that need to be taken into account

Today, climate change is considered the greatest environmental threat of the 21st century, representing a transversal concern and leading to the strong growth of renewable energies, either by implementing new systems or by increasing their energy capacity.

Hydropower is one of the most important and most widely-used renewable power sources. Perhaps because it has a great advantage: it depends much less on weather conditions than wind or solar energy. However, hydropower production has negative environmental impacts, namely: regulation of river flow, various changes in aquatic habitats and the mortality of fish caused by turbines and grids.

“Hydropower should always be a strategic priority, in a hybrid production system, with different sources of renewable energy”, explains the CERIS researcher Isabel Boavida. Thus, despite being a so-called “clean” energy, “the consequences for the ecosystems that support them are diverse”, she adds. This is why, “it is necessary to develop mitigation measures that reduce these impacts, otherwise we will face habitat degradation with potential costs for biodiversity”, concludes Dr Isabel Boavida.