Hazardous exogenous geological processes in the mountains under the pressure of human activity: 15-year observations from a natural landscape to a large ski resort

Recent studies reveal an ongoing worldwide increase in a number of slope instability manifestations and their positive correlation with human activity. The latter involves construction activity as one of the most common trigger or susceptibility raising factors. In this study, we conduct a detailed analysis of an extensive and rapid transformation of a forest-covered mountain landscape and its response. The study area is a mountain sport cluster of the Winter Olympic Games-2014, which developed from scratch to a large tourist resort in just a few years. A time-series of aerospace images were used for a comprehensive mapping of the land cover changes and associated development of slope instabilities over 15 years, from a “pre-construction era” until now. We identify widespread deforestation and the land cover changes in upper chains of the fluvial systems to be the key drivers of the enhanced multiplication and intensification of the slope hazard processes. Completion of the active construction phase leads relatively quickly to a gradual natural stabilisation of the slope-located processes. However, the stream-located processes need several decades to regain a balance, because the increasing energy of small watercourses, due to growth of surface runoff coefficient, led to the transformation of longitudinal profiles of their channels. The obtained results provide a refined look at the anthropogenic influence on the slope instability occurrence and their short-time evolution in a mountain forest landscape. We also discuss the prospective course of events for this resort.