The study area selected for the TUNDRA project is the Basin of the Usa River in the East-European Russian Arctic. The area is located at the latitude of the Arctic Circle. It has a total surface area of nearly 100.000 square kilometres. The Usa River flows from the Ural Mountains in the East to the Pechora River in the West, which in turn drains into the Pechora Bay and the Barents Sea.