Rivers That Feed the Danube: Major Tributaries

The Danube, Europe's second-longest river (2,850 km), is fed by numerous tributaries across 19 countries. Key contributors include:

Major Tributaries (by discharge/basin size)

• Tisza (Hungary, Serbia, Romania, Ukraine) – largest sub-basin.
• Sava (Slovenia, Croatia, Bosnia, Serbia) – largest by discharge.
• Drava (Italy, Austria, Slovenia, Croatia, Hungary) – major alpine tributary.
• Inn (Switzerland, Austria, Germany) – contributes significant alpine flow.
• Prut (Ukraine, Romania, Moldova) – forms part of Romania–Moldova border.
• Siret (Ukraine, Romania) – major Romanian tributary.
• Ialomița (Romania) – smaller but notable.
• Isar (Germany) – alpine tributary joining near Deggendorf.

Hydrological Importance

These tributaries drain the Alps, Carpathians, Dinaric Alps, and Pannonian Basin, giving the Danube a diverse flow regime (spring snowmelt, summer rain peaks) and supporting rich wetlands like the Danube Delta (UNESCO biosphere reserve).