List of tributaries of the Danube
The Danube is Europe's second-longest river. It starts in the Black Forest in Germany as two smaller rivers—the Brigach and the Breg—which join at Donaueschingen, and it is from here that it is known as the Danube, flowing generally eastwards for a distance of some , passing through several Central and Eastern European capitals, before emptying into the Black Sea via the Danube Delta in Romania.
Danube–Black Sea Canal
The course of the canal follows mostly the course of the former Carasu River, originally a tributary of the Danube. Therefore, hydrographically it also has the function of conveying the runoff from a drainage basin to the Black Sea.