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.
Brigach
Shortly thereafter, the Brigach leaves the Black Forest behind, about halfway along its course, and enters the much flatter Baar region near Villingen, which is dominated by open countryside, with larger settlements than in its upper reaches. In the middle of the town, it changes direction to the south and receives a number of tributaries from the north, of which two are from the Black Forest to the west and are more than 10 kilometres long: the "Warenbach", whose confluence is in the borough of Villingen, and the "Holenbach" whose confluence is in the next municipality of Brigachtal. Below the village of Klengen, the Brigach passes over the boundary of the district into the borough of Donaueschingen. Once again, the valley passes through wooded hills, the river develops meanders and then swings left on an easterly course through the urban part of the borough. In the left-hand part of the castle park, a karst spring, which has been regarded as a source of the Danube for centuries and whose upper reaches are called the "Donaubach" ("Danube Stream") is routed underground through the park into the Brigach. Its confluence is marked by a temple dedicated to the former German Emperor, Kaiser William II. Compared with its two headstreams, this source of the Danube is, however, hydrologically insignificant. A mile and a half east of the "Donaubach" spring, the Brigach unites with the Breg, a river which joins from the right and originates in the High Black Forest, to form the River Danube.