Low water levels on the Danube – Federal Government and viadonau strengthen measures to ensure shipping Water levels at 2003 and 2018 levels. BMIMI and waterway operators respond: proactive maintenance, new "Flexible Infrastructure" and international cooperation
The Danube is currently experiencing exceptionally low water levels. The water levels in the free-flowing sections are around 60 cm below the long-term low water level value, in the Wachau there is only 2.0 meters, east of Vienna 1.8 meters of navigable water in the deep channel available. Freight shipping has largely come to a halt, and cruise shipping is also significantly restricted. The Federal Ministry for Innovation, Mobility and Infrastructure (BMIMI) and the state waterway operator viadonau take the development seriously and intensify the existing measures to ensure shipping.
"The Danube is one of Austria's most important transport routes – for freight transport, tourism and thousands of jobs along the river. If climate change puts this infrastructure under pressure, then it is our duty to invest with foresight instead of waiting. That's exactly what we do: with 30 million euros annually, we invest proactively in the maintenance of the Danube waterway – through continuous maintenance, new technical solutions such as Flexible Infrastructure and through close cooperation with our European partners," emphasizes Federal Minister Peter Hanke.
Situation comparable to 2018
The current low water period is on the level of the most significant comparative years 2003 and 2018. 2018 was the last historic low water year: at that time, transport volumes on the Austrian Danube fell by 25.1 percent, from 9.6 million to 7.2 million tons. The share of the Danube in the modal split fell from 10 to 8 percent. This year too, a decline in transport volumes is expected due to the low water levels. Although there are no official bans, the loads of freight ships must be significantly reduced, so that a shift of transports to rail or road currently appears to be more economical. Many river cruises are only possible in a restricted manner or not at all, so passenger numbers will drop in 2026.
Unusual about the current situation is also the timing: low water phases usually occur in late summer or autumn according to experts.
Navigable channel secured despite record low levels
The long maintenance of shipping is mainly possible through the foresighted, year-round maintenance of the waterway by viadonau: multi-day water level forecasts for the shipping operators as well as ongoing dredging of the current shallow spots. As a result, despite the historically low water volume, it is possible today to ensure a navigable water depth of 1.8 meters east of Vienna and 2.0 meters in the Wachau.
"We have learned from the experiences of 2003 and 2018. Our maintenance today is even more proactive and data-driven than ever before. That we can ensure navigability despite low water is the result of years of consistent work on the waterway," says viadonau Managing Director Hans-Peter Hasenbichler.
New technology in pilot operation: the "Flexible Infrastructure"
In addition to traditional maintenance, viadonau is currently testing the so-called "Flexible Infrastructure": Unmotorised transport barges are loaded with gravel from maintenance dredging, positioned laterally outside the navigable channel and secured with anchors. This specifically directs Danube water into the central navigable channel, where higher flow speeds result in fewer gravel deposits and thus less dredging effort. The pilot trial is being carried out as part of the EU project FAIRway Danube II and co-financed by the Connecting Europe Facility of the European Union. Comparable pilot trials are also taking place in Croatia, Romania, and Bulgaria – the exchange of knowledge and experience between the countries allows a more targeted further development of the method.
International cooperation as a long-term response
With a catchment area of around 800,000 km² from the Black Forest to the Black Sea, low water levels on the Danube are a European challenge. Austria has therefore been coordinating international cooperation projects such as FAIRway Danube for years, with the help of which particularly Southeast European Danube states have been able to acquire important equipment such as survey boats and dredgers. As part of the EU Danube Region Strategy (EUSDR) and the TEN-T Core Network Corridor Rhine-Danube, an updated Danube Declaration is also being developed, which the transport ministers of the countries bordering the Danube will sign in Brussels at the end of September.
Scientific classification: Climate change as a driving factor
"What we are observing here is not an exception, but part of a longer-term development. Extreme low water periods will become more frequent in the course of climate change – and sometimes much earlier in the summer, as we are currently experiencing. It is all the more important that on the one hand nature-based approaches such as renaturation including stopping the deepening of the river bed and technical solutions like Flexible Infrastructure are already being developed and tested, so that we are prepared for future extreme events," explains Professor Helmut Habersack from BOKU Vienna.