Cargo boats are stranded on the Danube near Sarengrad in Croatia, and long-submerged vessels have emerged from the exposed bed of the Drava River near Osijek, as drought and prolonged heat drain Balkan waterways to their lowest levels in recorded history. Navigation has halted on stretches of both rivers, cutting fuel and goods transport through a corridor that connects Central Europe to the Black Sea.
Germany's Low Water Information System, known as NIWIS, recorded extreme low levels at 78 percent of Danube measuring stations and 44 percent of stations on the Rhine by the end of July. The figures place this summer's drought among the worst on the continent in the modern measurement era, affecting shipping lanes from Bavaria to the Serbian plain.
In Serbia, the river collapse has squeezed fuel imports and reduced capacity at hydropower plants that depend on consistent water flow. River traffic on the Danube, Europe's second-longest waterway, serves 10 countries on its route from Germany to the Black Sea, and the shipping standstill in the Serbian and Croatian stretches disrupts supply chains across the broader region.
Serbian meteorologists said a sustained heatwave began this week, with temperatures expected to reach around 40 degrees Celsius in some areas by Friday. Forecasters warned the intense heat could persist for close to a fortnight, deepening the drought rather than breaking it. Similar heatwave warnings were issued across the broader Balkan region.
Authorities in Serbia and neighboring countries have put wildfire services on heightened alert. The combination of record low river levels, dry soil and temperatures approaching 40 degrees Celsius creates conditions in which fires spread rapidly and are difficult to contain. Regional emergency management agencies have prepositioned equipment and personnel in forested areas most at risk.
On the Drava near Osijek, the receding water has exposed boats that sank or were abandoned decades ago, drawing observers to riverbanks that now stretch wide as sandflats. On the Danube near Sarengrad, the sandbars run for hundreds of square kilometers, leaving working cargo vessels too little depth to maneuver. River cruise operators have already pulled their boats from the affected sections; only small fishing craft are attempting the shallows.
The Danube has also fallen to record lows in Hungary, extending the disrupted navigation zone well beyond the Serbian and Croatian reaches. Europe's rivers drop in summer as a matter of course, but the depth and persistence of this year's decline has pushed levels below any comparable point in the available record at several gauging stations along the river's lower half.
Energy vulnerability is acute in countries that rely on the Danube system for both hydroelectric generation and fuel barge deliveries. When river levels drop sharply, hydropower output falls and the barges that carry diesel, heating oil and coal to inland depots cannot run full loads or must wait for conditions to change. Serbia, which imports a meaningful share of its petroleum products by river, faces supply pressure that feeds through to fuel availability at the retail level.
No coordinated regional emergency response mechanism has been activated publicly as of Sunday, and no international body has declared a formal crisis. Governments along the river are managing the disruption through national transport and energy agencies, adjusting import logistics and monitoring water levels daily as they await any shift in the weather pattern.
Forecasters see no near-term relief. The heatwave that Serbian meteorologists described as long-term is expected to hold through at least mid-August, and without significant rainfall the rivers have no mechanism to recover quickly. The Danube's flow depends on snowmelt from the Alps and Carpathians earlier in the year and on summer rainfall across its entire basin—both of which have been deficient this season.
