ИСТИНА

A joint study of permafrost conditions and factors, influencing permafrost processes in Yamal has been executed in the framework of the collaboration between Total (France) and FSBI SOI (Russia). The joint study included climate change reconstruction, permafrost and types of coasts analysis, Quaternary geology investigations, seabed geomorphology, etc. All of the results have been included and analysed in a GIS which allowed to get complex information about the territory of Yamal Peninsula. The climate change reconstruction shows a retrospective of the dynamics of climatic parameters influencing coastal dynamics and permafrost properties for Yamal Peninsula: temperature, duration of the ice-free period, etc. Another important issue influencing Arctic coasts is the amount of wave energy, which depends not only on the wind strength and direction, but also on the length of the wave fetch which depends on the distance from the coast to the ice margin, and therefore, on the decreasing sea ice cover in the Arctic. The terrestrial permafrost analysis included gathering information on Quarternary geology, types of permafrost, thickness and types of seasonal thawing, permafrost temperatures, etc. The study also included seabed geomorphology for the southern part of the Kara sea, seabed sediments composition, and a digital elevation model in order to evaluate the particularities of the sea bottom relief. Based on the bottom geomorphology and also on information about ice condition, charts of ice impact have been included in the GIS and analysed; the most dangerous zones have been revealed. In the part dedicated to coastal dynamics, we have gathered satellite imagery and topographic data. Based on them, maps of types of coasts for Yamal Peninsula have been made. Accumulative and stable coasts today occupy a greater part of the Yamal coastline, than the abrasion coasts, however, the latter are quickly destroyed. Apart from the type of coasts, the cliff height, the landform and in some cases type of sediments composing the coast has been indicated. This will allow to evaluate the stability of the coasts and to select areas with increased natural risk. In order to get more details on coastal dynamics, we have selected two key areas: with accumulative coasts (Sabetta area) and with thermoabrasion coasts (Kharasavey). We used multi-annual satellite imagery to evaluate the rates of coastal retreat, which helped us to understand the particularities of the coastal dynamics development for these territories, and to predict risks and dangers for the infrastructure situated in both of these areas, which are now being actively explored by human activity. The comprehensive approach to permafrost analysis using satellite imagery, topographic data, and digital elevation models united in a global GIS helped to better understand the links between different kinds of natural processes in Yamal Peninsula, which are now quickly changing due to both natural and human-induced reasons, and have approached to the prediction of their dynamics in the future.