Dynamics of the ground thermal regime along linear projects in Central Yakutia

Abstract

This article discusses the thermal response of upper permafrost to anthropogenic disturbances. It presents the results of experimental geocryological investigations conducted in support of geotechnical exploration and construction of linear engineering projects.

The geocryological conditions in the study area, as well as the methods of permafrost thermal monitoring are described. The research focuses on the upper permafrost within the depth of annual temperature fluctuations. Field observations involve repeated surveys of the disturbed landscapes, including measurements of snow depth, snow density, soil properties, thaw depth, and ground temperature in the cold and warm seasons. The study aims to explore active layer thickness and near-surface permafrost temperatures, the variables which indicate changes to the ground thermal regime in the pipeline, railway, road and powerline corridors. The observation results demonstrate significant increases in mean annual temperature of the upper permafrost layers, as well as in seasonal thaw depth following tree removal, ground surface stripping and post-fire clearing. Soil thaw depths along the linear corridors show a distinct increase from year to year, in places reaching the top of ice wedges and causing permafrost degradation. The development of hazardous cryogenic processes is reported. Quantitative estimates have been obtained for the thermal dynamics of the ground on selective, gradual and clear cuts, as well as on old and recent burns in relation to plant succession stages.

The results of the study have been used in the design and construction of linear structures. Observational data can be further used in predicting the thermal dynamics of disturbed landscapes and in developing guidelines for rational land management.