Geomorphologic system analysis of a high mountain valley in the Swiss Alps

摘要

Geomorphologic processes in alpine environments are often reinforced compared to other systems as steep slopes, high relief, and highly variable climatic conditions increase process intensity. We discuss the geomorphologic system of a high alpine valley in Switzerland based on a detailed geomorphologic map at a scale of 1:25,000. The map displays the distribution of surface materials, geomorphologic landforms, and processes in the Turtmann valley, Valais, Switzerland, a southern tributary of the Rhone valley. The constitution of landform elements is employed to construct a qualitative model of the sediment transfer in the valley's system. We distinguish four subsystems that represent different geomorphologic conditions. Process coupling, sediment cascades, and paths of sediment transport are discussed for the subsystems. Although periglacial and glacial processes strongly influence the sediment movement in the hanging valleys, they do not affect the sediment output of the subsystems, due to climatic and surface structure conditions. While coarse debris is stored inside the hanging valleys, sediment output from the Turtmann valley system mainly consists of fine debris, which is transported by fluvioglacial processes. We are convinced that geomorphologic mapping represents a key tool for geomorphic system analysis, and serves as a basis for the development of sediment budget models.