PROJECT DESCRIPTION
BACKGROUND
Untrammeled flooding, gravel and mud shifted to and fro, steep banks, oxbow lakes, nutrient-rich woods and meadows are just a few of the hallmarks of dynamic floodplain ecosystems. Such an ecosystem on the Danube east of Vienna, part of central Europe's greatest coherent floodplain forest zone, was the scene of a pitched battle in 1984 to prevent a hydro-electric power project putting an end to these very dynamics. Demonstrations, occupations of the building site, a Cabinet crisis followed each other in succession. In 1996 the floodplain was made a national park. The competent authorities for nature conservation and water management at federal and regional level (Vienna, Lower Austria) as well as the NGOs rolled up their sleeves, for there was work to be done: a century of Danube river regulation had cut side channels off from the main stream, deepened the river bed and led to the terrestrialization of associated stagnant waters, culminating in the loss of valuable habitats. The recipe for dealing with this was clear: more water and greater dynamics for the Danube floodplains.
OBJECTIVES
A concept to connect the various bodies of water in the floodplain with the main river had already been made before the LIFE project, which would draw up the detailed technical plans and carry out the first reconnections at Orth and Untere Lobau. Among others, this would entail lowering the river dyke at several points, changing weirs and dams, re-arranging banks and constructing a gravel island. This would not only revitalise the floodplain ecosystem, but would also serve the very practical purpose of protecting Vienna against floods. Instead of following conventional wisdom and strengthening the dykes, the river would be given more room to sprawl. In the medium term the dyke closest to the river was to be breached so that the old floodplain itself would become a retention basin. Wetland habitats and their denizens, such as the fish Umbra krameri which was considered extinct in Austria until its sensational rediscovery in 1992, would of course profit, but so would less obvious cases such as the valuable dry grasslands on the dykes along the river. Intensive PR-work was envisaged to secure the support and comprehension of local inhabitants and visitors for all these measures.
RESULTS
The project's most important aim was the restoration of more natural dynamics to the floodplain system of the Danube i.e. a higher "permeability" of the riparian forests for flood events. This was achieved by lowering the river banks and changing existing weirs so that the natural hydrological regime was not hindered and more water would flow into the forests and former side channels, creating more natural structures. The effects of these works were impressive and the subsequent self-restoration process of the floodplain dynamics topped all expectations. The project actions thus have considerable demonstration value and conservation benefit. All measures required an extensive technical planning, status quo inventories and permits. The following measures re-opened outlets from the main river into the floodplain area, or tackled river morphology. Apart from successfully boosting the dynamics of the floodplain morphology, they also served as examples for further hydrological restoration actions: Restoring a permanent water flow through the Lower Lobau by the technical modification of a weir at "Gänsehaufentraverse", including platforms for visitors, plus elaboration of ecological monitoring reports and of a general hydrological management plan for the future functioning of the restored weir; Hydrological restoration of two large side channels running through the floodplain forests near the village of Orth ("Großer Binn" and "Kleiner Binn") - near-permanent water flow ensured by lowering the "Treppelweg" dyke, removing weirs, clearing channels, etc.: three 20 m water inlets at Gollingscharte/Kleine Binn and two at Große Binn, construction of a small bridge at Tiertraverse, removal of weir at Badwandltraverse and removal of block embankments. Construction of a tower to allow three years' photo documentation of the site; Restoration of near-permanent flow conditions through the side channel at Schönau by lowering the "Treppelweg" dyke, removing two weirs and constructing two small bridges at Obere and Untere Traverse; Preparatory planning and creation of six new gravel islands in the main channel of the Danube and reshaping of banks using gravel. Furthermore, the project undertook species and habitat conservation actions: Development of a management plan for the recurring management of meadows in the foredyke area of the "Lower Lobau" (Viennese part of the National Park), with special reference to the corncrake and ecological monitoring; the actual corncrake-friendly mowing management of the foredyke meadows was not charged to LIFE-Nature; Preparatory botanical inventories of the calcareous meadows on the dyke "Marchfelddamm", management concept for the dyke meadows and ecological monitoring, annual mowing of the dyke meadows (to be continued with regional funds after the end of the project); Actions for the threatened fish species Umbra krameri (European mud-minnow), consisting of habitat improvement actions (restoration of ditches and digging of 'survival ponds' at 16 places around Orth and Eckartsau) and re-introduction of mud-minnows (7 re-introductions, of which 5 were successful), as well as ex situ conservation ("aquarium and garden pond project": school aquarium, 4 museum and zoological institution aquariums, 8 private breeding partners). The project developed a global concept for hydrological restoration in the National Park area which, based on the experience when carrying out the measures, includes more radical river and floodplain channel restoration measures, which would not have been accepted some years ago. Following on from this, it did the detailed planning for 8 target sites (re-dynamisation of floodplain area, lowering of dykes)to be tackled after the LIFE project, started the permit preparation for the hydrological restoration of Stopfenreuth and Spittelauer Arm/Tiergartenarm and launched continuous data collection in order to prepare further hydrological projects (gauge recording). Meanwhile some of the LIFE project's innovative side channel re-connection actions have been transposed to other river engineering projects along the Austrian Danuber river. In terms of communication and dissemination, the beneficiary carried out intensive press work, published a National Park newspaper four times a year informing about the LIFE project (“Aublick”), included a LIFE presentation in the National Park yearbook, set up a website www.donauauen.at, held information seminars in all communes of the National Park area as well as presentations at local schools, and produced information folders, brochures and panels. There was extensive networking - national and international (SK, DE, HR, YU, HU, RO, BU).