The Danube River, filled to overflowing by heavy rains and melting snow, has risen to its highest level in more than a century, and thousands of families have fled their homes across the Balkan countries and in Hungary. Some 8,000 people across the region are sheltering in public buildings, in tents and with friends and relatives on higher ground, and authorities warn that thousands more may have to be evacuated.
Floodwaters have rolled over some 300,000 hectares (740,000 acres) of land in Romania, Bulgaria, Serbia and Montenegro, according to government estimates - destroying homes, roadways and bridges.
In their attempts to avert further disasters, officials in different countries are using widely varying techniques. Romania today breached a dam on its Black Sea coast to let the Danube flow straight into the sea. In periods of drought, the dam is intended to hold water for emergency release into the environmentally fragile Danube Delta.
In Bulgaria, all Danube ports, with the exception of east Rousse, are flooded and have closed, officials said. Five of Romania's nine Danube ports are shut down. In Hungary, more than 23,000 people, including 500 military personnel, are battling the floods by strengthening the dams and dikes.
In Serbia, the floods forced the Djerdap 2 power plant on the country's border with Romania to stop generating power. According to first estimates, nearly 220,000 hectares of land and 3,000 houses are reported flooded.
In Vienna, the International Commission for the Protection of the Danube River (ICPDR) promised that international efforts to prevent and reduce flood impacts in the Danube River Basin will be strengthened by the end of the year. Overseen by ICPDR, a new flood warning system will supplement national systems and give up to 10 days warning of expected floods.