FIThydro

Mitigating the effects of hydropower plants Hydropower is an important source of renewable energy, yet hydropower plants can also represent a significant threat to the health of fish and the ecology of their habitats. We spoke to Professor Peter Rutschmann about the work of the European research project FIThydro in developing innovative solutions to mitigate the impacts of hydropower plants.

A significant proportion of Europe’s electricity is generated by hydropower plants, which provide a reliable, sustainable supply of energy to companies and consumers.

While hydropower is a major source of renewable energy, it is also important to consider the impact of hydropower plants on the surrounding environment and aquatic life. “Many hydropower plants – especially the older ones – have serious effects on the environment,” says Professor Peter Rutschmann. This is an issue at the heart of the FIThydro project, an EU-funded project which brings together 26 science and industry partners from across Europe. “The aim of the project is to find solutions for mitigating the effects of hydropower plants in an economical and cost-effective way,” explains Professor Rutschmann, the project’s Coordinator.

Hydropower plants This encompasses the effects of a hydropower plant on both fish and the habitat in which they live. One major problem is that a bypass is often not available for fish migrating downstream past a hydropower plant, and if it is, fish may not use the bypass – or fishway – , leaving them highly vulnerable. “Often fish don’t use the fishways because there is relatively little water in them, compared to the water going through the turbines. If they travel through the turbine, then there is a likelihood of them being killed. The estimated damage or mortality caused by the turbine passage used to vary considerably, depending on the formula available for calculation.

With our research, we can now predict this likelihood quite precisely,” says Professor

Visit at the hydraulic laboratory VAW at the ETH Zurich, Switzerland.

Rutschmann. Hydropower plants also affect the environment. “Most hydropower plants have a reservoir. The velocity of the water, the water depth, and also the granulometry of the reservoir bed, are completely different to what they were before,” continues Professor Rutschmann.

The conditions for fish in rivers today are thus often quite different to those that their predecessors experienced, which makes it difficult for them to find or reach their spawning grounds. This is one of the more serious examples of the impact of hydropower on the environment, an issue Professor Rutschmann and his colleagues are addressing in the project. “We have to look at that, and to find solutions to improve the habitat,” he outlines. This includes

both enhancing existing solutions and developing new tools to mitigate the impact of hydropower plants and comply with the European Water Framework Directive. “We are focusing on rivers. The important point with rivers, in terms of the Directive, is that all aquatic species should be able to travel both upstream and downstream,” says Professor Rutschmann.

A hydropower plant represents a significant barrier in this respect. Now researchers are investigating the behaviour of fish using data from different test case studies across Europe, part of the wider goal of helping to protect and sustain fish populations over the longer term. Fish have adapted to their environment over the course of evolutionary history, yet they have not adapted to the

The hydropower plant Freudenau on the Danube in Vienna, Austria, is one of the test cases in the FIThydro project. © Verbund

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Additional fish habitats are created in this fish pass at the river Günz, Germany. © Mathias Schlagenhauser

The FIThydro Consortium.

To study fish movement, fish are tagged and then detected with a portable antenna at the test case Bragado, Portugal. © Hidroerg

At the test case Bannwil, Switzerland, routes and impacts of downstream migration are investigated. ©BKW Energie AG

Computational hydrodynamic model of the hydropower plant Bannwil. © VAW, ETH Zurich

Measurements of substrate composition at the test case Schiffmühle, Switzerland. © VAW, ETH Zurich

The innovative Barotrauma Detection System sensors measure the pressure fish experience during turbine passage. © Jeffrey Tuhtan

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presence of hydropower plants. “If we could understand how they behave, then we could build much better hydropower plants,” says Professor Rutschmann. “We are conducting experiments to observe them, and from this we can see that different species behave differently. We’ve done tests with fish in the field at test case sites as well as in the laboratory, and we’ve learned that fish have individuality.”

The evidence shows for example that some trout behave very differently to others, so while it is possible to statistically assess how certain species will behave, there will be exceptions. Once researchers have a deeper understanding of the behaviour of the fish, they can then look at measures to help them avoid hydropower plants and reduce mortality rates.

A variety of different species may be found in a river, including catadromous and freshwater fish. One well known species

The project is also involved in developing a number of other innovative devices, which can be used to more accurately assess the fish mortality rate around hydropower plants.

The path of healthy fish through a turbine can be computed using complex, 3-dimensional tools, which can lead to deeper insights.

“The turbine is modelled, the velocity and turbulences are modelled, and then a sort of virtual fish is passed through this computed flow field. You can see what pressure changes it will experience, and whether this virtual fish will be hit by the turbine blades,” outlines Professor Rutschmann. “From this data you can then assess whether the fish will survive or not. We have also tried to adapt this approach to different river conditions.” Such computations are important for hydropower operators to see if and how they might need to adapt the turbine operation mode to enable a safer turbine passage during migration periods.

The impact of climate change is another important consideration in the project, with rising water temperatures affecting the distribution of different species. Fish tend to migrate in search of suitable conditions, so in some cases they may swim upstream to find areas with lower water temperatures, yet Professor Rutschmann says this can be challenging for the fish itself. “Upstream you have higher velocities, because of the slope.

Some fish may not have the swimming ability to cope,” he points out. A lot of data has been gathered in the project on how different species swim, which will help researchers build a clearer picture in this respect. “We’ve looked at how fish swim upstream, and we’ve seen clear differences between species,” outlines Professor Rutschmann. “This will help to design better solutions such as fishways and migration habitats that enable different species to successfully migrate upstream past a hydropower plant.”

The research results will feed into the development of a risk-based DecisionSupport System, to help operators, engineers and water authorities work effectively and mitigate the impact of a hydropower plant. Additionally, a Fish Population Hazard Index has been developed, through which the threat

posed to fish species by hydropower can be evaluated, while Professor Rutschmann and his colleagues are also working on a Cumulative Impact Assessment tool. “This will help us to understand what happens to fish which have to pass round a series of hydropower plants. For example, a salmon, when entering into a river system, may have to negotiate several hydropower plants,” he says. “We have developed a series of innovative solutions, tools and devices that can be employed for different aspects of hydropower impact mitigation.”

A number of these decision-making tools are designed to be used during the refurbishment of hydropower plants.

However, there is no single perfect solution for all cases, as Professor Rutschmann says hydropower is very site-specific. “The ideal solution for each site may be different,” he acknowledges. The cost of these solutions is another important consideration in terms of the project’s wider agenda. “There is a clear need to mitigate the effects of hydropower plants on ecology and fish. We sometimes see solutions that are effective in terms of mitigation, but which are not very economic.

It is important in the project to find the right trade-off between costs and efficiency,” says Professor Rutschmann.

FIThydro Fishfriendly Innovative Technologies for Hydropower

Project Objectives

The project’s aim is to develop cost-effective environmental solutions, strategies and measures to avoid fish damage and increase the ecological compatibility of hydropower production. For this, technologies, methods, tools and devices are applied and enhanced at test sites across Europe.

The results from the research are combined in different online accessible tools that help practitioners evaluate, plan and find solutions for fishfriendly hydropower.

Project Funding

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 727830.

Project Partners

• TUM • FVB.IGB • CNRS/PPRIME • IST-ID • SINTEF • ECOLOGIC INSTITUTE • ETHZ • UHULL • TALTECH • SJE • EV INBO • NTNU • GEA-ITAGRA • LEW • UNIPER • VOITH HYDRO • AF-CONSULT • BKW • LKW • HIDROERG • FLUSSBAU iC • FISHCONSULTING • SAVASA • STATKRAFT • VERBUND • SWECO • https://www.fithydro.eu/consortium/

Contact Details

Project Coordinator, Professor Peter Rutschmann Technical University of Munich Arcisstr. 21 80333 Munich Germany T: +49 89 289 23161 E: info@fithydro.eu W: https://www.fithydro.eu/ : @fithydroproject Professor Peter Rutschmann

The aim of the FIThydro project is to mitigate the effects of hydropower plants on fish in an economical and cost-effective way. investigated in the project is salmon, while researchers are also investigating other less well-known species, such as the bullhead, a protected fish on the red list of threatened species, which led to some interesting insights. “The bullhead is a very bad swimmer. However, in our experiment it survived all turbine passages, whereas we had high mortalities with trout and other strong swimmers,” Professor Rutschmann explains. Evidence showed there is a lower mortality rate with bad swimmers, which led researchers to look at the idea of electrofishing and to develop a protection device that can be installed in front of a turbine. “With this device the fish is quickly paralysed, and the mortality rate is reduced by a factor of 2. This is a relatively simple device, and it can be applied on existing turbines,” says Professor Rutschmann.

Test cases

Peter Rutschmann is a full professor at the Technical University of Munich. He has 40 years of experience in hydraulic engineering and expertise in physical and numerical as well as hybrid modelling. He has managed some 50 hydropower projects, 35 sediment and flood management projects and also a few eco-hydraulic projects. He is one of the inventors of the innovative TUM hydroshaft powerplant and owns 8 patent families.

Peter Rutschmann is a member of IAHR and the coordinator of the FIThydro project.

There are 17 test cases within the project, located in four regions which are broadly representative of European river systems.

Scandinavia is a very important region in terms of hydropower production, while test cases have also been established in the Alps, France/Belgium and the Iberian Peninsula.

“In the Iberian Peninsula we have a very rare fish species, which is well-adapted to very dry Summer conditions,” says Professor Rutschmann. This species may however be adversely affected if water is redistributed due to hydropower operation and more generalist species are attracted to the area. “This original Iberian fish species may have difficulty in adapting to the presence of a generalist. So these changes in water distribution can lead to the loss of this very specific species,” continues Professor Rutschmann.

EU Research

The nature-like fishway at the hydropower plant Freudenau enables fish to migrate upstream. © Verbund

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