The Danube floods twice a year, first in early spring and again in early summer.
The repeated occurrence of exceptional floods within a few years, such as the Rhine floods in 1993 and 1995 and the Elbe and Danube floods in 2002 and 2013, suggests that floods in Central Europe may be organized in flood-rich and flood-poor periods.
The Danube broke through flood defenses in southeastern Europe, driving thousands of people from their homes on its banks in Serbia, Romania and Bulgaria, officials said.
In the capital, water welled up from the sewage systems in some places, prompting fears that the Danube was endangering flood defenses and subway stations Crowds of onlookers gathered Sunday night to stare in amazement at the river that runs across the city.
In Baden-Württemberg, the situation differs between the Neckar and upper Danube catchment, where floods mainly depend on local precipitation, and the Rhine Valley, where floods are also possible in seasons with snow and ice melting in the upper Rhine catchment.
Traveling to Liberland by car involves a cross-country trip across Croatian B-roads, dirt tracks, and dales, with the last few miles a drive along the top of the dam that protects the surrounding area from the Danube's occasional floods.
The Red Tide reached the Blue Danube yesterday, when the flood of crimson toxic sludge from a Hungarian industrial accident began contaminating Europe's second-longest river.
Dozens of settlements along the Danube are facing record flood waters but so far the defences are holding, the BBC's Nick Thorpe reports from western Hungary.
Until it was regulated in the 1870s, the flood-prone Danube split into a tangle of different routes as it passed Vienna.
For example, there is a tendency that flood-rich/-poor years in sub-catchments of the Rhine basin, which are dominated by winter floods, coincide with flood-rich/-poor years in the southern sub-catchments of the Danube basin, which have their dominant flood season in summer.
