Socialist Federal Republic of Yugoslavia
Regarding rivers, the Danube was navigable throughout its entire course in Yugoslavia, linking the ports of Belgrade, Novi Sad, and Vukovar with Central Europe and the Black sea. Long stretches of rivers Sava, Drava and Tisza were also navigable.
Vienna Danube regulation
In Vienna, the Danube river up until 1870, was almost totally unregulated. The river flowed through wetlands on the left (east) bank of today's Danube course. Villages like Jedlesee, Floridsdorf and Stadlau that were near the former main branch of the Danube were particularly susceptible to flooding.