Traisen Project
LIFE+ River Restoration – New Floodplain Landscape in Lower Austria
General Description
The Traisen Project, financed under the EU LIFE+ Programme, is Austria's largest land restoration project. Its aim was to transform the lower reaches of the Traisen river near the Danube power plant in Altenwörth into a diverse floodplain landscape. During the construction of the Danube power plant (1973–1976), the Traisen was lengthened by 7.5 km. The LIFE+ project broke up the straightened section and completely recreated the Traisen's mouth into the Danube.
Rather than restoring an existing river course, the project created a wholly new, dynamic 10 km Traisen river with meandering banks, a large estuary at the Danube, 30 ha of running water habitats, and 60 ha of flood zones for silver willow wetlands.
Innovative Aspects
- Despite a 10-year preparation phase, this is not a classic river restoration – a completely new river course was created rather than restoring an old one.
- Large quantities of excavated material were used to shape an ecologically functional riverbed – a key innovation.
- Largest LIFE+ project in Austria in terms of planning area and construction volume.
- A fish-passable network was established linking the new Traisen, its water bodies, and the Danube, benefiting ~40 local fish species.
Environmental / Social / Economic Aspects
Environmental:
- 30 ha of running water habitats created
- 60 ha of riparian forests and flood zones
- 15 ha of wetland ponds for local biodiversity
- Fish-passable network for ~40 species
- 30 ha of natural meadows permanently improved
- 25 ha cleared of invasive species (neophytes)
Social: Agreements with landowners for permanent maintenance. Citizen information events held in Zwentendorf, Traismauer and Altenwörth (2011).
Economic: Significant improvement of fish stocks with lasting impact on Danube fish fauna. Economic compensation for landowners for pecuniary disadvantages without use of LIFE money.
Link to Spatial Policy
The project created new flood zones covering about 60 ha on the new river – a key spatial policy feature integrating NbS into land-use planning and reducing flood risk. The European conservation area "Tullnerfelder Au" habitat was directly improved.
Challenges & Solutions Applied
The project created a 10 km-long Traisen river with surrounding bank zones and a large estuary at the Danube. Near the Altenwörth power plant, the Traisen's waters were diverted into this new riverbed, while the old canal was retained for flood relief and as a standing water body. The new river features natural banks, shallow amphibian zones, and successfully controlled invasive plant species (neophytes) across 25 hectares.
Key Takeaways for Replication
- Cross-sectorial approach combining environmental, social, and economic benefits is a key success factor.
- Involvement of third parties and landowners is essential for effective NbS implementation.
- Long preparation phases (10+ years) are compatible with ambitious restoration goals.
- Project significantly reduces flood risks while enabling local biodiversity to thrive.