The Séveraisse is a sub-tributary of the Rhône via the Drac and the Isère.
Situated in the Valgaudemar valley, it rises in the glaciers of the Massif des Écrins and flows into the Drac at La Trinité. It is 33 kilometres long.The Séveraisse has twenty-nine tributaries, the largest of which are:
Le Gioberney mountain stream,
Navette stream,
Prentiq mountain stream.