The maintenance of the international Danube waterway is carried out by making optimal use of resources with the greatest possible degree of efficiency and effectiveness regarding the implementation of maintenance works and taking into account the prevailing conditions (e.g. limited market capacity in hydraulic engineering or budgetary guidelines as laid down by the federal government).

viadonau has adopted a proactive approach in its efforts to ensure the provision of internationally specified fairway parameters on the Austrian section of the Danube. The objective is to ensure that the shallowest sections of the river are maintained and in good condition prior to the onset of the annual low water period in autumn. For both ecological and bedload management reasons (degradation of the riverbed), all dredged material is returned to the river, being either dumped in the river, used for structuring the riverbanks or for landfill on islands. Maintenance dredging doesn't only take place in the fairway but also beyond its limits, including approaches to ports, landing stages (e.g. also in backwaters), the approach to locks and waiting areas for vessels.

All such measures are carried out in close coordination with the other relevant organisations responsible for the maintenance of waterway infrastructure on the Austrian Danube. These include the Verbund Hydro Power GmbH, the public Danube ports and the City of Vienna (MA 45 - Water Management Authority) .

Maintenance measures also need to be taken, when necessary, on the hydraulic structures used for low water regulation. These include groynes, training walls and bottom sills. The planning and implementation of maintenance measures is conducted in close coordination with the teams from the Integrated River Engineering Project and Environment / Ecology at viadonau.

Secondary infrastructure

Aside from the maintenance and renovation of hydraulic structures such as groynes and training walls, viadonau is also responsible for the maintenance and, where appropriate, restoration of the secondary infrastructures of the waterways Danube, Danube Canal, Traun, Enns and March. These include revetments, public transhipment and mooring sites, quay walls, or bollards that are owned by the state.

In the future it is envisaged that these structures will be included in an IT-supported maintenance management system that will provide an optimised analysis of current conditions and enable all necessary maintenance and reconstruction measures to be carried out more effectively and efficiently.

Naufahrten

On the basis of internal guidelines for downstream journeys and shallow section monitoring, the fairway of the total Austrian Danube is surveyed on a monthly basis by viadonau using measurement vessels equipped with sonar. As a result, current data concerning the shallowest sections on free-flowing sections are made available for ship operators to download from the Austrian RIS website (DoRIS) as part of our customer oriented waterway management.

Fairway depths at critical shallow sections are available on the DoRIS site.

Water / weir supervision

Water and weir supervision are just two of the sovereign functions that viadonau carries out in accordance with the provisions of the Waterways Act.

Coordinating with the supreme water rights authority, the federal states of Upper and Lower Austria and the energy supplier VERBUND Hydro Power GmbH, viadonau is entrusted with the task of monitoring and inspecting the retaining dams of the Danube power plants, along with all installations (including pumping stations, Dotation facilities etc.). Inspections are carried out on a quarterly basis and include the checking of all rivulet mouths and the observation of sedimentation trends in the reservoirs. An exception to this is the Danube power plant at Freudenau where these inspections are conducted by the City of Vienna.

As part of the weir supervision, and especially in the event of flooding, each power plant on the Danube is monitored to ensure it complies with the applicable weir operation regulations.

A corresponding annual report is submitted to the supreme water rights authority.