The Influence of Dirty Snow Avalanches on Soil Development

Snow avalanches are a natural hazard that is – depending on its size and location – destructive and potentially harmful to humans, livestock and infrastructure. Because of that there is a lot of research on avalanche formation and how to protect residents and mountaineers from them.However, some avalanches also function as geomorphic agents. This is the case for full-depth glide or wet snow avalanches that release after melting periods with high air temperatures or rain-on-snow events. These avalanches erode sediment and vegetation as they glide over the ground and transport the material to their deposition areas. Since they appear as brownish-grey in the landscape, they are referred to as “dirty snow avalanches”.So far, no efforts have been made to investigate the influence these dirty snow avalanches have on soil and landscape. Thus, this research aims to bridge the gap by investigating two avalanche slopes of different lithologies in the Tyrolean Alps (Austria): one at the Hahntennjoch (limestone) in the Lechtal Alps and one in the Kraspes Valley (gneiss) in the Sellrain. We analysed in total 24 soil profiles and their soil properties in the avalanche deposition areas and nearby control areas where avalanche activity was presumed absent. Furthermore, an erosional spot in the release area at Hahntennjoch was accessed and investigated.We will present the results of these analyses and compare avalanche and control sites as well as the two study areas with each other.