Mass wasting processes affecting the surface of an alpine talus slope: Annual sediment budgets 2009–2018 at Flüelapass, eastern Swiss Alps.

Abstract

AbstractAn alpine permafrost talus slope at Flüelapass (Eastern Swiss Alps) was observed using annual terrestrial laser scanning measurements between 2009 and 2018. The high‐resolution digital elevation models derived from these measurements enabled the detection and quantification of mass wasting processes with an accuracy of a few centimeters. Rock fall, snow avalanche erosion, and debris flow tracks could be distinguished and their quantitative and qualitative contribution to talus slope growth and shaping was examined. Erosion rates were calculated for each of the investigated processes and an estimate for the recession rate of the talus slope head wall is reported. Currently, debris flows supply most of the debris inputs to the talus slope, while snow avalanches were found to play an important role in reshaping its surface morphology. Rock fall causes distinct grain size sorting down the slope, as the travel distance of rocks increase with their size. The presented data and results illustrate the current processes occurring at the talus slope surface, which appear to differ in quantity and quality from those during the onset of the talus slope formation.