The Vorderrhein is one of the two sources of the Rhine. Its catchment area of 1,512 square kilometres is located predominantly in the canton of Graubünden,Switzerland. The Vorderrhein is about 76 kilometres (47 mi) long, thus more than 5% longer than the Hinterrhein. The Vorderrhein, however, has an average water flow of 53.8 m3/s (1,900 cu ft/s), which is less than the flow of the Hinterrhein. According to the Atlas of Switzerland of the Swiss Federal Office of Topography, the source of the Vorderrhein—and thus of the Rhine—is located north of the Rein da Tuma and Lake Toma.

The Rhine is one of the major European rivers. The river begins in the Swiss canton of Graubünden in the southeastern Swiss Alps. It forms part of the Swiss-Liechtenstein, Swiss-Austrian, and Swiss-German borders. After that the Rhine defines much of the Franco-German border, after which it flows in a mostly northerly direction through the German Rhineland. Finally in Germany, the Rhine turns into a predominantly westerly direction and flows into the Netherlands where it eventually empties into the North Sea. It drains an area of 9,973 km2 and its name derives from the Celtic Rēnos. There are also two German states named after the river, North Rhine-Westphalia and Rhineland-Palatinate.