Final answer:
The Danube River's source is at the confluence of Breg and Brigach in Germany's Black Forest. It's part of a river system connected by the Rhine-Danube Canal, integral for trade and transport, different from the Rhine River, which flows to the North Sea.
Step-by-step explanation:
The river whose source is on the confluence of the Breg and Brigach Rivers, in the Black Forests of southern Germany, is the South-flowing Danube River. This significant European river continues to flow into the Main River, before joining the Rhine and eventually reaching the North Sea. The Rhine-Danube Canal plays a critical role in connecting these river systems, enabling the movement of species and ships across regions and serving as a significant thoroughfare for trade and transport.
The Rhine River, another major European river mentioned, flows in a different direction than the Danube. The Rhine flows northward and empties into the North Sea at Rotterdam, one of the world's busiest ports. Both the Rhine and the Danube have played vital roles in European transportation and trade throughout history.