IMPORTANCE OF PERMAFROST CHANGES FOR INFRASTRUCTURE EXPLOITATION AND ENVIRONMENTAL PROTECTION (CASE STUDY OF LOCAL INVESTIGATION IN LOWER PART OF VORKUTA RIVER)

The permafrost state is one of the important factors of environmental stability in Arctic Region. The new data on trends and patterns of the evolution of permafrost conditions in the southern part of the Bolshezemelskaya tundra was gathered as a result of Vorkuta engineering geocryological educational practice in Geological Faculty of Moscow State University. These data will be taken into account in the construction and maintenance of the infrastructure elements such as railroads, highways and pipelines.
The set of standard and innovative methods of the permafrost survey was used. Three major types of landscape were characterized by geophysical, remote sensing, geomorphologic and thermometric measurements. The large mounds, linear water discharge depressions, and rounded thermokarst depressions were studied in link with permafrost and hydrologic conditions. The continuous warm permafrost was mapped with taking into account the depth of its table. The typical mean annual temperature at the bottom of the active layer is –0.5°C and the depth of the permafrost table varies from 0.4 m at the top of organic reach mounds to 12 m at the linear intermound depressions.
Each type of landscape was characterized by the annual temperature regime analysis. The mounds with reach organic soil demonstrated the normal regime with seasonal ground thawing. The mineral mounds have the relatively thin zone of seasonal temperature change which has the depth no more than 5 m. The thermokarst depressions have no deep seasonal ground freezing because the strong thermal insulating effect of the snow cover.
The linear water discharge provides the warming of the ground taliks. Along the water-streams the water temperature decreases for 1°C for a kilometer of the flow.
The modern permafrost dynamics reflects in the regional permafrost warming with retaining of the continuous permafrost extent. The permafrost thawing progress mostly from the top, the lateral thawing is reduced. The active thermokarst process grows in adjacent zone of peat reach mounds.

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