The Integrated River Engineering Project for the free-flowing Danube in the Austrian Alluvial Zone National Park: contradictory goals and mutual solutions.

The Upper Danube River has been almost completely transformed into a chain of impoundments. For the major remaining free-flowing section, the 50 km stretch from Vienna to Bratislava (Alluvial Zone National Park), a large-scale Integrated River Engineering Project has been developed over the last two years. It aims to (1) stop riverbed degradation, (2) improve navigation, (3) improve fluvial dynamics within the inshore zones, (4) enhance the lateral connectivity between the river and its floodplain and (5) reduce high water levels at flood periods. The decided planning principles focus on an adaptive, step by step implementation and should benefit both the nature values of the area and the navigation. This paper presents the expectations and cornerstones of the project, as well as outlining river engineering strategies and ecological options. Benefits of the project, potential conflicts between the different stakeholders, and perspectives for the sustainable development of the main channel are discussed.