Mapping cryogenic processes and assessing the sustainability of permafrost landscapes in the North-East Arctic Siberian taiga and tundra from Landsat 8, Sentinel 2, and DEM data

International audiencePermafrost landscapes are one of the most sensitive ecosystems that humans inhabit. Geocryological conditions determined by the presence of ice content, the genetic type of sediments, and the active layer are one of the most important variables for classifying the vulnerability of an ecosystem to disturbances in vegetation and soil cover. These variables indicate cryogenic processes that can be activated during the degradation of permafrost. Cryogenic mapping is an important parameter for assessing the state of permafrost and infrastructure design in permafrost landscapes. However, the methods of remote sensing spatial modelling for understanding the distribution of cryogenic processes in the Arctic Siberian mountainous areas with continuous permafrost are still insufficient. The cartographies at the regional scales of 1:500 000 are inexistent. We need for permafrost landscape maps is increasing with the development of the North-East Siberian Arctic for the infrastructures and urban centres' risk assessments. Orulgan Ridge in North-East Siberia is one of these territories. This study examines the Orulgan Ridge region, as a case area, where we developed maps of the distribution of cryogenic processes based on the detailed landscape structure (including classification of environmental variables, vegetation covers and genetic type of sediments) with time-series Sentinel 2 MSI and Landsat 8 OLI, and stereogrammetric digital elevation model of the ArcticDEM data. The combination of Random Forest classifier and geomorphological GIS terrain analysis has successfully distinguished 6 classes of boreal mountain taiga and 3 classes of arctic tundra and mountain desert. Based on the indicator parameters of the interrelation of ecological variables (such as vegetation and topographic position) adopted in permafrost-landscape cartography, we carried out the regionalization of cryogenic processes. We made a classification of the genetic type of deposits, which determines the likelihood of the development of dangerous cryogenic processes. Only 5 zones of high risk have been identified according to the prevalence of thermokarsts, thermoerosion, frost cracking, soil suffusion, thermodenudation, and their combinations.The assessment of the sustainability of mountain permafrost landscapes integrates two scenarios using GRID modelling based on the annihilation of the vegetation by the mining industry and forest fires. To determine the sustainability of permafrost landscapes, median values were calculated, an indicator of variation (standard deviation) of environmental variables - elevation, vegetation association bio productivity, slope, aspect, average temperatures of July and January, and precipitation. We established the ranges of ecological potential values: optimal, suboptimal, and pessimal. The ecological potential models within which the landscape can maintain its characteristic structural and functional features. The low sustainability potential is characteristic of the zones with the development of thermokarst and soil suffusion. This state creates many environmental restrictions in the field of environmental management associated with the quality of human security. The analysis of cryogenic processes and the sustainability assessment give good potential modelling for the territorial planning, and the environmental restoration, and provide a quantitative method for achieving landscape sustainability in Arctic urban and industrial centres