LIFE Project Germany-Austria: Restoring the River Inn’s hydrological dynamics and floodplain habitats

The Inn valley straddling the German- Austrian border is one of the most important areas for wildfowl and waders in Central Europe. The birds are attracted to four artificial lakes, which were created in the 1950s when hydro dams were constructed across the River Inn. Thanks to the river’s strategic location at the foot of the Alps, and under the influence of the Inn’s river dynamics, these lakes are now a haven for more than 120,000 water birds annually, with some 285 bird species recorded since the 1960s.

This birds’ paradise is also surrounded by alluvial forests dominated by alders (Alnus glutinosa) and willows (Salix spp.) and oak-elm-ash communities. By the late 1990s there was a growing awareness that the high quantities of natural silt brought down by the River Inn from the Alps were putting this area at risk in the longer term. These fine sediments were causing an accelerated 'terrestrialisation' of the site’s habitats (i.e transforming the wetlands habitats into drier habitats) threatening its attraction to birds both as a staging point and as an over-wintering site for waders and waterfowl.

Together with the Upper Austrian Government the Bavarian Environment Ministry applied for funding for this first German-Austrian trans-boundary LIFE project. Its main objectives were to restore the river’s sediment transport dynamics, as well as to preserve the terrestrial habitats of the floodplain. The project area covered 3,200 ha, including a 46 km reach of the river Inn, as well as the riparian woodlands on the Bavarian side.

The project aimed to prevent the Inn’s habitat types from becoming progressively choked with sediment. This would be achieved by restoring the hydrological dynamics of the river/ floodplain, more specifically by restoring the erosion, sediment transport, and sedimentation processes in the area. To this aim, the Austrian partner opened up 100 metres of the river dyke to allow the water to drain into the Hagenauer Bucht, a 2 km2 wetland area.

This ‘river enhancement’ action was based on detailed flow models, which enabled the preparation of the works and an assessment of potential risks, including the possible erosion of the flood dykes. The hydrological models recommended the opening of the dyke, determined the optimal size and location of the opening, and provided a scientific basis that could potentially be applied to other areas of the Inn floodplain In order to restore or enhance the terrestrial habitats of the floodplain and to facilitate nature conservation management actions, the project also purchased 108 ha of alluvial forests.

This action included:

• The management of 73 ha of alluvial oak-elm-ash forests or grey alder forests, where 10.2 ha of non-native trees were removed;
• The reinstatement of traditional coppicing management of grey alders on 1.7 ha;
• The conversion of 22 ha of arable land to grey alder forest, and the testing of various techniques to speed up alder growth;
• The recreation of a mosaic of habitats consisting of hay meadows, ponds, sedge wetlands, dunes and gravel flats. The most important example was realised behind the flood dyke near the village of Eglsee, where 7 ha of formerly arable land were recreated in this mosaic of habitats, which had almost disappeared over the last century.

Sheep grazing was reinstated along 10 km of dyke. This proved a cost-effective ecological measure to maintain the flower-rich dyke grasslands in the longer term. The project hired local farmers and forestry workers to do much of the work. This helped to increase the local acceptance and support of the project, as following the project’s closure, some locals continue to be employed in 'After-LIFE'maintenance work.

Various stakeholder groups along the river.

The project actions had a direct benefit on habitats, species and birds of the Habitats and Birds Directives. The project managed to create 21.9 ha of alluvial forest and new aquatic habitats on the floodplain suitable for amphibians and wildfowl and waders. Moreover, the restoration of the river hydrodynamics had a positive impact on the shallow water and sand habitats, thus increasing local biodiversity. "It was great to learn that local and trans-boundary conflicts of interest can be solved satisfactorily due to EU funding and within a concrete, time-restricted project." said Dr. Zahlheimer. "LIFE also contributed to a good relationship between local authorities, hunters and anglers as well as the general public, which still exists five years after the project’s closure." added Christine Kotz of the Landratsamt Passau, a project partner.

This close cooperation with all concerned parties and with the local electricity companies, who were project partners, helped guarantee the project’s success and made it possible to combine resources and expertise from both sides of the Inn. Collaboration with another EU programme – the Interreg II project 'AENUS', which targeted a trans-boundary, integrated zoning concept for tourism and the local economy, contributed to the integrated approach taken by the LIFE team. A good deal of media/public relations work was also undertaken by the project. This resulted in the publication of a number of press articles, information sheets, two brochures and a LIFE project calendar. Public meetings were held in the villages and an exhibition toured schools and municipalities. In addition, two visitor platforms and five information panels were erected in order to guide and channel visitors. The Info Centre Ering still offers monthly tours in the LIFE area.

For more information go to http://ec.europa.eu/environment/life

Project Number:

LIFE98 NAT/D/005372 Title: Lower Inn with riparian woodland

Beneficiary: Bayrisches Staatsministerium für Landesentwicklung und Umweltfragen