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.
Traisen (river)
The Traisen is formed from the rivers "Türnitzer Traisen" and "Unrechttraisen". Its total length, including the "Türnitzer Traisen", is . It is a tributary of the Danube in the Lower Austrian region of Mostviertel. Its two sources begin near St. Aegyd am Neuwalde and Türnitz respectively. After meeting, they flow through the municipalities of Türnitz, Lilienfeld, Traisen, Wilhelmsburg, and St. Pölten, before meeting the Danube at Traismauer. In the course of building the Danube Factory Altenwörth, the mouth of the Traisen was relocated to Altenwörth in the municipality of Kirchberg am Wagram.