Danube Watch 1/2020 - We're Getting to the Bottom of the Danube
We're Getting to the Bottom of the Danube
It has been over 30 years since the composition of the riverbed east of Vienna was last systematically inspected. Now a major probing campaign has been completed.
In the framework of the Catalogue of Measures for the Danube east of Vienna and the inclusive waterway management of viadonau, about 150 volumetric samples of the riverbed were taken in grid-like arrangements with an excavator-pontoon from Felbermayr Bau & Transport GmbH over the entire free-flowing section. The samples, which were packed in Big Bags, each had a weight of up to 300 kilograms.
Of course, this activity was also affected by the currently dominant Coronavirus pandemic. All participants had to adhere to strict safety guidelines such as wearing masks, keeping safe distances from one another, etc. With these guidelines, well-coordinated cooperation was necessary.
Important Groundwork for Bedload Management and River Engineering
Knowledge of the state of the Danube riverbed is the solid foundation of a range of tasks at viadonau. Both the current bedload management in the free flowing sections as well as river engineering and ecological projects can potentially be better optimised and planned with the help of such knowledge. For example, the particle size distribution of the gravel is collected along the longitudinal course and over the channel width and the progress of the Danube riverbed over time. This way, the determination of riverbed roughness can serve as a basis for hydraulic modeling, areas with coarse sediment localised with regard to damage potential for shipping as sediment grain size also has a corresponding effect on natural bedload transport.After the Sample-taking, Begins the Analysis
After the sifting and analysis of the gravel samples, a comparative scientific analysis of the riverbed material for both of the stretches of the Austrian Danube will be created through cooperative research between the University of Natural Resources and Life Sciences Vienna (Institute of Hydraulic Engineering and River Research), the Engineering office Klasz and viadonau. In this way, a temporal comparison of the development of the Danube riverbed over the past 30 years is planned on the one side, while a spatial comparison between the two free flowing sections of the Danube around the Wachau and east of Vienna is planned on the other side.Joint Statement
The ICPDR linked up with the Danube Commission and the International Commission for the Protection of the Sava River Basin in 2007 to execute an intense, cross-sectorial discussion process, which has led to the `Joint Statement on Inland Navigation and Environmental Sustainability in the Danube River Basin´.The Joint Statement provides principles and criteria for environmentally sustainable inland navigation on the Danube and its tributaries, including the maintenance of existing waterways and the development of future waterway infrastructure. The process involves selected representatives of navigation authorities, environmental protection authorities, industries and environmental organisations throughout the basin.
The Differing Strategies of Bedload Management
On the one side, 235,000 m3 of sediment is added annually to the riverbed east of Vienna by Verbund Hydro Power GmbH, below the hydropower plant Freudenau. The other side, within the framework of conservation dredging, as well as by means of sediment management, is being operated by viadonau with sediment return (dumping the dredged materials as far upstream as possible).In the Wachau, bedload-management takes place through the construction and current allocation of about 13 gravel islands/ gravel structures along the Danube – also out of materials from the conservation dredging for navigation. This approach has been led for over 10 years within the framework of the LIFE Nature Project Wachau, and has seen to ecological shore structures and free-flowing sections along the river ever since.
viadonau and the ICPDR
Viadonau has enjoyed long-standing and intense cooperation with the ICPDR. The PLATINA Manual on Good Practices in Sustainable Waterway Planning, several Joint Danube Surveys, the Stakeholder Forum of the Bad Deutsch-Altenburg Pilot Project and Danube Day are among the many joint activities that have characterised a partnership which extends far beyond a simple observer role. For projects in the Danube region as well, the ICPDR has always been a constructive partner.
