Causes of Temporal Variations in Mass Wasting Occurrence in the Ursern Valley, Switzerland

Considerable changes in land use and management practices together with an increased frequency of extreme weather events in mountain regions are considered major factors in the susceptibility of landscape to mass wasting in the Alps. An increase in mass wasting events since 1970 as well as uneven spatial and temporal distribution of mass wasting events was found on analysis of alp inspection reports between 1950 and 2000. These were written annually by farmers commissioned to supervise pasture use and report on conditions prevailing on the communal land in the Ursern Valley, Switzerland. To investigate variations in mass wasting frequency, controlling parameters such as climate and grazing patterns and intensity were analysed using the regional archive. The results infer that land use changes and maintenance measures modified the effects of an increasing number of high magnitude rainfall events by changing landscape susceptibility to mass wasting and land degradation since 1950.