Activation of thermokarst after forest fires on the Yansky plateau: tha case of Verkhoyansk area

Thermokarst is one of the striking processes that characterize the dynamics of permafrost landscapes. It represents the process of soil subsidence due to thawing of underground ice. Under the influence of external factors, such as climate change, forest fires, deforestation, the invasion of silkworms, etc., there is an acceleration of the process of degradation of permafrost soils. The situation is also aggravated by the release of greenhouse gases trapped in permafrost soils, which, in turn, accelerate the process of climate warming. The study of thermokarst makes it possible to assess the scale of degradation of permafrost and to quantify the impact on climate warming.

Manifestations of thermokarst processes on ice-saturated soils of the Yanskiy plateau are considered. The climatic conditions of the investigated area, as well as survey geomorphological and lithological features of the distribution of soils on it. The degradation of permafrost under the influence of forest fires has been assessed. The thawing of underground ice in the “Chogoro” area was calculated according to the classification of the digital elevation model using the interpretation of images from unmanned aerial vehicles. The main methods of work are landscape cryoindication and remote sensing. Aerial photographs were processed using Topodrone, Agisoft metashape and ArcGIS software. A step-by-step method for calculating the volume of thawed ice in two areas is presented. The rates of degradation of frozen soils for key areas were revealed in the range from 5.2 to 10.5 cm / year. The volume of melted ice was 16364 m³ and 17985 m³.

Comparative analysis of landforms obtained from digital elevation models based on aerial photography data revealed a good correlation with a digital surface model based on satellite imagery data, which was confirmed by field measurements. The amount of ice that has melted indicates large-scale releases of greenhouse gases into the atmosphere, accelerating the rate of global warming. The rate of degradation of permafrost soils after forest fires on icy soils is undoubtedly intensified or accelerated.

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