Through the valleys of Andorra flow numerous water courses that come together to form the Valira River. The Valira basin is Y-shaped and consists of two more tributaries: the Valira del Norte and the Valira de Oriente (east).
The Valira del Norte is born in the lakes of Tristaina, it has a journey of 14 km and it passes through Ordino and the Massana until arriving in Encamp, where it joins the Valira del Este. This second tributary of the Valira originates in the most eastern part, has a journey of 23 km, passes through Canillo and Encamp and ends also in Escaldes-Engordany. Together, they form the great Valira, which runs 11.6 km.
The average annual flow of the river is 13 m3 per second. It flows south and ends up in the Segre River which, in turn, is a tributary of the Ebro.
Map of Valira River: