Abstract: The object of this research is the thermokarst occurrences, namely polygonal microrelief and frost cracking, which are the causes of natural hazards for the main water pipeline. The article demonstrates displacements, gaps and cracks in the pipes and fixtures of water mains, caused by thermokarst occurrences; satellite images indicate areal zoning of polygon microrelief. Thermokarst occurrences are detected by satellite images and publicly available on the website https://www.yandex.ru/maps/; the methods of field observation and photosurveying were applied,  the engineering-geological information and library material were processed. The method of areal zoning of the territory of activation of polygonal microrelief is based on the satellite images. The study was conducted by means of field observation on the key sections of the main water pipeline, as well as by processing of archival data acquired from engineering surveys of previous years. The obtained materials allow determining the current geocryological situation of the territory of the water pipeline and spread of negative cryogenic processes and phenomena. Based on the satellite images was described the method od areal zoning of the territory of polygonal microrelief and cracking, earlier proposed by the author. As a result of research, it can be concluded that frost-breaking cracks are the cause of stress-strain state of the water pipeline, and satellite images show the spread of areal zoning of polygonal microrelief and cracking.

Abstract: The object of this research is the ice wedge casts and concomitant polygonal microrelief. The subject of this research is the delineation of ice wedge casts on the margin of southern exposure of the Lake Churapcha in Central Yakutia. It is a known fact that in permafrost areas, a pronounced polygonal microrelief is a sign of the presence of ice wedge casts. In geology, “delineation” is the outlining of contours and delimitation of boundaries of the deposits, minerals, and zones with different quality of mineral raw materials and mining-geological conditions, according to the data of geological study for rational development. Ice wedge casts and there is such deposit. The article summarizes the results of field engineering and geological surveys conducted in 1995 on the shore slope of southern exposure the lake that contains ice wedge casts. The author also examines the data from modern satellite images for detecting the activation of polygonal microrelief. The surveys of 1995 confirmed the widespread occurrence of ice wedge casts in the indicated district. According to geological section, the ice wedge casts were identified and delineated. The results of section of the bottom of lake-reservoir demonstrate that it is located in the “thawing bowl”. The presence of ice wedge casts is also indicated by a pronounced polygonal microrelief, which is confirmed by satellite images. As a result of climate warming, the upper limit of ice wedge casts may also change, approximately to 0.3 m, which depends on the air temperature, amount of precipitation and depth of seasonal thawing.

Abstract: This article covers the history of scientific research of the Nizhnekolymsk tundra, conducted over the period from 1970 to 1987 by the employees of the Institute of Biology of the Yakut Branch of the Academy of Sciences of USSR (Yakutsk). The subject of this research is the biochemical composition of plants from the family of sedge and grass – Егiорhorum роlуstасhiоn and Arctophila fulva) as the most common communities. It was conducted in tundra pastures in the lower reaches of the Kolyma River for rational economic management. One of the largest state owned farms of Yakutia “Nizhnekolymsky” specializes in reindeer herding – the traditional activity of indigenous peoples, was located in this area. In the past, this area was referred to as Hallerchinskaya tundra; it covered low left bank of the Kolyma River from delta to the forest boundary on the south and Konakovsky uplands in the west. Within the limits of Hallerchinskaya lowland in the rural locality of Pohodsk was located the “Nizhnekolymsky” geobotanical station. The method of models developed by staff members of the Institute of Biology was applied in monitoring the formation of aftergrass and determination of productivity reserve, as well as in selection of quadrats in the subarctic tundra. The main conclusions consists in the statement that the use of the such method for determining the phytomass reserve allowed conducting a prolonged observation over aftergrass formation in the same quadrats, and thereby discerning the natural development process towards reduction or increase of the studied species.

Abstract: The object of this study is the permafrost soils of the section of the route of the main water pipeline «Tabaga-Byuteidyakh» in rural areas of Central Yakutia, spanning approximately 28 kilometers. Permafrost soils are widely developed in the Southeastern part of Central Yakutia, and are located on the Leno-Amginsky interfluve. They lie in the upper part of the geological section and are underlying on the lane of the main water pipeline route, as well as fall into the foundations of engineering structures of industrial facilities and hydraulic engineering construction. The study is based on a complex of field engineering and geological surveys, as well as laboratory studies of the physical and mechanical properties of rocks. The article discusses the features of the composition, structure and properties of rocks in this area. It is noted that among the considered soils, there is a variety of granulometric types, cryogenic texture from massive to layered, with clay soils usually of higher ice content than sandy ones. Technogenic loads are also mentioned in the form of objects of the main water supply system, consisting of pumping stations, pipelines, reservoirs and channels, which lead to significant changes in the geocryological environment and surrounding landscapes.