Today, the banks of most water bodies containing dams are covered with wave breakers made of concrete. They commonly do not host ecologically-rich habitats. According to the EU Water Framework Directive, these are considered to be „significantly modified water bodies". Water resides longer in them, leading to possible higher water temperatures and eutrophication. Dam restoration activities mostly consist of replacing the old concrete without improving the environment for flora and fauna. When dams have to be elevated, they become broader on the land side, which increases land consumption and has a negative impact on the floodplain forests. The approval procedures are time-consuming and the costs for restoration and elevation of dams are quite high. Due to climate change, torrential rains and flooding are expected to occur more frequently, making it even more important to maintain dams and to quickly restore them. In some cases, it is necessary to elevate dams to match the consequences of climate change. Under the EU Floods Directive, flood risk management has to be implemented to avoid major hazards for citizens.
LIFE+ INADAR aimed to demonstrate a new approach for dam restoration by implementing eco-berms in two hydropower locations of the ODK (Obere Donau Kraftwerke AG) in Germany: Offingen and Oberelchingen. Eco-berms make it possible to restore and elevate dams in line with the Floods Directive and improve the ecological potential in line with the Water Framework Directive. The project partners designed efficient and cost-effective eco-berms that are suitable for dams of different functions. For both demonstration sites, detailed implementation plans were developed with stakeholders. At the water storage area in Offingen, over 500 m of eco-berms were constructed. In Oberelchingen, the water storage dam was also restored and elevated by 70 cm in an area of more than 500 m. Recommendations were developed for future implementations of eco-berms.
LIFE+ INADAR successfully demonstrated an innovative approach for dam widening and elevation, which yields manifold ecological and social benefits, and is about one third cheaper than the conventional approach. It reduces carbon dioxide (CO2) greenhouse gas emissions, as natural materials (e.g. stones, sediment, dead wood, with groynes and sealant material) replace concrete. The project team constructed eco-berms at two hydropower dams on the River Danube in Germany, at Offingen and Oberelchingen, over 500 m lengths in each case.
The idea behind the project's approach is to widen the dam not on the land side, which destroys valuable alluvial forest, but to add newly-developed eco-berms on the water side. Eco-berms make it possible to carry out restoration while: a) elevating the dam (after making it wider) in line with the Floods Directive; and b) improving ecological potential, as demanded by the Water Framework Directive, by creating nature-like habitats on the water-side of the dam. This increases both the efficiency and the cost-effectiveness of the measures.
Construction at Offingen was completed in March 2017, and the dam widening with eco-berms at Oberelchingen was finished in August 2017. The elevation part at the latter site will be completed after the eco-berm has settled and extended a further 1 500 m on both sides of the Danube. In July 2020 the authorities finally set the required dam elevation to 41 cm. This can easily be done as the dam is already widened.
The project's eco-berms are suitable for all dams, where the capacity of the river is not critical for flood protection, for example, water storage at hydroelectric power stations and on inland waterways. It is estimated that thousands of kilometres of dams in Europe could be suitable for the INADAR approach. The demonstration value of the project is very high, because the effects are clearly visible, the sites are easily-accessible, and the riverbank stretches with and without eco-berms are next to each to provide direct comparisons. All stakeholders, including authorities, nature conservationists and fishing associations, were in favour of the win-win eco-berms, which offer multiple advantages, like legal compliance, lower costs, ecological enhancement instead of damage.
Before the project, riverbanks next to the hydropower stations had little vegetation, very poor fauna, and low fish populations. The implementation of eco-berms changed this dramatically. The solution has promoted vegetation, enabled the spawning of a broader range of fish, offers habitat for macro-zoobenthos in the water and for birds (nesting and hunting) above, and enables valuable alluvial forest to be saved. New habitats for flora and fauna have been created along more natural riverbanks. The number and population of fish has increased considerably (including some endangered species) and the number of plant species found along the riverbanks with eco-berms has more than doubled.
However, simple permissions were not achieved within the projects duration, because the permission system was unprepared for this innovation.
The INADAR approach has already been replicated successfully. The hydropower company Verbund in Austria has implemented eco-berms at one of its reservoirs, while the hydropower operators TIWAG, Juniper, Stadtwerke Mnchen and EW Reutte (Austria) are planning to do so. Flood risk management is the main driving force for large-scale replication.
The project contributes to the implementation of the EU Water Framework Directive, Floods Directive, and Habitats Directive. In addition, the BayKompV (Bavarian Compensation Regulation), which uses a point-scoring system for the ecological impacts of new construction, is applicable to these eco-berms. The project team compiled a guideline containing the highlights of the know-how for the planning and permission processes. It recommends that the EU compiles an official statement and in a second step lists the eco-berm approach as an exception e.g. in the WFD, allowing for an easier approval process. Indicators similar to those of the INADAR project could facilitate the permission process.
Extensive and ongoing monitoring is validating flood protection (e.g. river water level, sediment development), ecological, and socio-economic benefits. Eco-berms offer high ecological benefits at one-third of the costs, while their construction can generate more jobs than concrete construction. They also improve recreational value (riverside bicycle and walking paths), transforming a "dead" canal into a vivid riverbank habitat.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).