At Duisburg, this river meets the Ruhr.
The St. Elizabeth's Floods of 1401 and 1421 occurred due to overflowing of tributaries of this river. In antiquity, the huge Hercynian Forest extended eastward from the valley of this river. An island in this river is the site of a tower where Hanno II was supposedly eaten by mice. One section of this river passes through Lake Tuma on its way through the town of Chur, where it turns to the north and flows into the Obersee of a certain lake. This river's length is marked by namesake "kilometers" that begin with zero in the city of Constance. A waterfall caused a "murmuring" sound near a rock on this river that was said to be home to a siren-like woman called the Lorelei. At Duisburg, this river meets the Ruhr. For 10 points, name this river that flows into the North Sea at Rotterdam after passing through Cologne and Düsseldorf in Germany.
The St. Elizabeth's Floods of 1401 and 1421 occurred due to overflowing of tributaries of this river.
the Rhine River