PROJECT DESCRIPTION
BACKGROUND
The Lafnitz is one of the last lowland rivers in Austria to have retained a semi-natural state, having been left to meander without intervention for over three-quarters of its 112 km course.
Consequently, it hosts numerous Annex II fish species, amphibians and Annex I birds in and around its loops, oxbow lakes, side channels and associated alluvial forests. The entire river area has been designated an EU Special Area of Conservation within the Natura 2000 network.
However, some parts of the river have been affected by the introduction of small hydro-power plants and other engineering projects. In particular, dams and weirs have interrupted some free-flowing sections, constraining migration and causing fish to become isolated.
Several areas of banks and riverbed had been altered into uniform profiles, fixed by blocks of stone often with no bushes or trees.
Many side channels and meanders had become choked with sediments through being separated from the main river course and were slowly drying up. Groundwater levels in the surrounding area were also dropping. In other parts of the river, the problem was increased stream velocity leading to an absence of quiet water refuges for wildlife.
OBJECTIVES
The Lafnitz LIFE project targeted almost the entire length of the river, starting upstream in the Styrian mountains of Austria and continuing to the lowlands in Hungary.
In crossing national boundaries and adopting a holistic approach to river management over an entire catchment area, the project followed the approach of the Water Framework Directive.
It aimed to remove obstacles to the migration of fish over the whole river course, including its side channels, to reconnect the meanders and to regenerate the dried-out alluvial forests. It also hoped to enable the floodplain area to redevelop its characteristic mosaic of flowing and standing waters, muddy banks, pioneer vegetation and forests.
The project thus sought to reunite isolated fish populations and recreate natural terrestrial, semi-aquatic and aquatic habitats providing spawning grounds for fish and amphibians and foraging areas for birds.
Specific tasks were to modify or construct fish bypasses around weirs and to restore parts of the riverbed. Bank protection would be removed to widen the river’s course. A number of dead side channels and inlets would be revitalised or reconnected and free flow would be ensured over the whole river course.
RESULTS
The project succeeded in linking habitats, restoring specific river landscape and re-establishing the continuum of the River Lafnitz, which is now passable to fish from its source to its mouth into the Raab. The area has been returned to optimal ecological condition while maintaining sustainable flood protection.
It achieved this through successful partnership between nature conservation and water management interests, supported by a range of municipalities and associations. It had 13 formal partners and crossed national borders, involving experienced Austrian organisations and Hungarian teams carrying out innovative work for their region.
Technical planning and permit procedures were carried out as foreseen. A total of 20 ha of land was bought to prepare for the necessary modifications. Five cut-off areas were reconnected to the main water flow. Bank protection was removed to widen the river at 14 locations over 15 km. The project also organised and paid compensation to four electricity plants to remove less water from the river.
The project’s activities resulted in an immediate rise in surrounding groundwater. Dried-out ponds and floodplain forests became wet again; the project created 3.2 ha of new water areas.
All of the foreseen 15 fish migration modifications were implemented. These included removal of ground sills and construction of nine new fish passes around weirs or other obstructions - including the biggest, which was 3.5 m high.
An 800m bypass channel was constructed making use of one disused side-channel. At the site of an old mill – the largest interruption to the river’s course – water is now diverted for 500m through a newly created meander. Six weirs were modified.
In addition, all of the foreseen 14 sub-tasks to create spawning and growing habitats for fish and amphibians were implemented. Sandbanks were created by using stones or groins and islands were formed. In Hungary, an 11 km river section of the Lahn-Patak was restored with islands, ponds, bank structures, trees and shrubs.
The project succeeded in restoring habitat types like alluvial forests with Alnus glutinosa and Fraxinus excelsior (91E0) and rivers with muddy banks with Chenopodion rubri p.p. and Bidention p.p. vegetation. This has helped preserve many species listed in Annex II of Directive 92/43EEC such as Zingel zingel, Misgurnus fossilis and Gobio kessleri.
The project has been the subject of frequent TV, press and radio reports, school activities and a major European conference. It is a model for other small, semi-natural rivers in Europe.
Further information on the project can be found in the project's layman report (see "Read more" section).