Brief description of Project Background

Geology: The river Liesing lies in the south of the City of Vienna, close to the city border, it leads through the small town Schwechat after leaving Vienna and then merges with river Schwechat. The river Liesing has two souces, the “Dürre Liesing” and the “Reiche Liesing”in the west of Vienna. While the Dürre Liesing arises from a limestone area, the Reiche Liesing arisies from the flysch limbestone area of the Wienerwald, which makes the river grow rapidly in case of heavy rainfall. In Vienna both rivers merge and have shaped the landscape through meanders, deposition of sediments and erosion.

In the 70ies the river was subject to a major revitalisation forcing it in a concrete river bed. Major housing development in the 90ies lead to a change in the sourrounding of the river with the setting up of small playgrounds and cycle roads next to the river. Despite the heavy flood protection, in 1998 and 2000 after heavy rainfall river Liesing burst its banks.

Taking into account the "Water Directive" the City government of Vienna decided to rebuild the area comissioning various landscape architecture offices. The aim of the project was to improve the situation at the river Liesing according to the EU Water Directive in order to archive “maximum ecological potential” of a heavily modified water body.

The specific aims of the project "Revitalising River Liesing" were: • Improvement of the water quality to quality class II according to the saprobic system. • Re-introduction of a diverse macrozoobenthos and river-specific fish species into the relevant river section. • Establishment of a string of aquatic ecosystems with restored ecosystem function and structure which may function as aquatic ecological corridor extending far into the urban area. • Creation of new habitats for priority species (council directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora). • International exchange of project results.