Source of the Danube of Baden): “Danube, the biggest river of Germany, rises at the Martinskapelle in a wild and lonely area of the Black Forest, is called Brege at its origin and forms the river Danube in Donaueschingen where it is unified with the Brigach." (German original: „Donau, der größte Fluß Deutschlands, entspringt bei der Martinskapelle in einer wilden und einsamen Gegend des Schwarzwaldes, heißt am Anfang Brege… und bildet erst in Donaueschingen, wo sie sich mit der Brigach vereinigt, die Donau.“) The identification of the main spring in the uppermost Bregtal (also called Katzensteig) is dependent on a defining convention: Instead of
Source of the Danube above and below Tuttlingen (see also Danube Sinkhole). As a consequence, it dries up most time of the year. Near Ulm, in terms of hydrology, the Danube gets a tributary to the Iller which is more water-rich. It even gets surpassed by the Inn. The Donaubach rises on the castle grounds near the left corner of the front face of the castle Donaueschingen in a karst spring. This karst spring has an embankment of 15 to 70 l/s and enters into the Brigach after flowing 90 meters belowground. The Brigach and the Breg become the Danube after 1.5 km. The