Risk of Anthropogenic Cryopeg Formation in Urban Areas in Central Yakutia

Abstract

Yakutsk, the largest city in the continuous permafrost zone, is used as a case study for examining natural and modified environmental conditions that control the character and intensity of water-logging in the active layer in relation to topography and drainage. Interpretation of aerial photography and satellite imagery was carried out, along with analysis of drilling and long-term hydrogeochemical monitoring data, in order to determine the response of natural landscapes to human impacts and to assess the probability of suprapermafrost cryopeg development with city expansion. The role of vegetation cover in controlling the temperature and moisture regime of the active layer was examined. Results suggest that the neighborhoods with chaotic development patterns and impeded drainage have high risk of cryopeg formation. Puddle water in these areas is characterized by high dissolved-solids levels (2-4 g/dm3). As puddles evaporate, salts settle on the underlying soil surface and then migrate into the active layer, increasing its salinity (up to 1.3%). Suprapermafrost water that forms in these soils has dissolved-solids concentrations as high as 8–10 g/dm3. Continuous supply of dissolved solids and their cryogenic concentration promote the formation of hydrochemical taliks and cryopegs. Remote sensing and mathematical modeling demonstrate that changes to the soil moisture and hydrogeochemical regimes cause forest degradation, which, in turn, promotes deeper seasonal thaw. This provides favorable conditions for the formation of subaerial water-bearing taliks and later anthropogenic cryopegs