In the upper course of a river valley the land is highest, steepest and most exposed. The weather in this part of the valley is colder, wetter, windier and more humid than the parts lower down. Snow lies here for longer than elsewhere. The soils are often acid, thin and waterlogged. All these limitations make it difficult to make use of the land in the upper course.

Farming is extensive, with forestry, hill sheep and deer stalking being common uses. Buildings and transport links are rare.

This lack of development makes the land attractive for hill walkers and rock climbers, and some areas in the highest part can be used for winter sports like skiing and snowboarding. The heavy rain does make the land suitable for reservoirs and the fast flowing rivers can be damned to make hydroelectric power stations.