The Gran Valira (Catalan pronunciation: [ˈgɾam bəˈɫiɾə], locally: [ˈgɾam baˈliɾa]) is the biggest river in Andorra. It flows through the capital, Andorra la Vella, and exits the country in the south near the Spain-Andorra road border crossing.

The Valira is a tributary to the Segre, which in turn is a tributary to the Ebro.

It flows into the Segre in La Seu d'Urgell. Its main tributaries are the Valira d'Orient, the Valira del Nord and the Madriu. The Valira river system is 35 km long.

The Ariège (Occitan: Arièja) is a 164 km long river in southern France, right tributary of the Garonne. Its source is in the Pyrenees, where it forms part of the border with Andorra. It flows north through the following départements and cities:

Ariège (named after the river): Ax-les-Thermes, Foix, Pamiers.
Haute-Garonne.

It flows into the Garonne in Portet-sur-Garonne, south of Toulouse. If the Latin origin of its name (Aurigera) is to be trusted, the Ariège is supposed to carry gold nuggets.