The Danube Floodplain National Park: A Fluvial Landscape with Expiration Date?

Situated between the European capitals Vienna and Bratislava in the Vienna Basin, the Danube Floodplain National Park covers one of the largest remaining floodplains in Central Europe. Here, the Danube River is still free flowing and forms the lifeline of the park. Prior to channelization in the nineteenth century, the Danube can be referred to as a high- to medium-energy variant of anabranching rivers that comprises both braiding and meandering elements. Between 1726 and 1817, main channel(s) and lotic side arms made up 85–95% of the total water bodies in the floodplain, pointing to the crucial role of river dynamics. Large shares of the fluvial landforms were permanently renewed by lateral bank erosion, avulsion of new channels or reoccupation of abandoned arms. River training programmes and flood protection projects in the nineteenth century severely truncated the system-inherent potential for channel adjustments. The consequences are the comprehensive stabilization of formerly dynamic fluvial landforms and the missing renewal of riverine habitats. Human interventions in the upstream Danube sections and lacking bedload influx also affected the morphological development in the national park. Today, the success of habitat restoration in such a channelized river reach is constrained by several factors. Locally, the requirements for unhampered navigation and the protection of the hinterland against floods are the most important concerns. Remote impacts, such as severely truncated bedload transport, restrain the recovery of the original river-typical fluvial processes and channel dynamics.