Underground Ice Research Articles

Some Remarks on the Phase Transformation of Gas Hydrates in Porous Sediments at Negative Celsius Temperatures

The article presents a solution to the problem of the phase transition of methane hydrate — methane-gas + ice in porous hydrate-containing sediments at a negative Celsius temperature in the medium. The numerical solution of the resulting system of differential equations of piezoand thermal conductivity makes it possible to effectively simulate the change in pressure and temperature in both time and space in a medium of any dimension during its heating or decompression. In this case, the medium is not subdivided into parts with varying phase states of methane hydrate. Instead, its sediment substance is considered as a single entity, with its physical properties changing in magnitude when the hydrates undergo phase transformation. As an example, the problem of the thermobaric regime of a heating spherical cavern containing ice, hydrate and free methane has been solved. This cavern is situated within a continuous gas-tight underground ice. The solution shows that although the temperature of the sphere surface increases considerably, the decomposition of hydrate only occurs in an extremely thin shell located directly between the surface and the displaced inward phase boundary.Over time, the stability conditions of hydrates establish anew but at a higher gas pressure and medium temperature. This phenomenon of severely limited decomposition of the hydrate in a closed gas-insulated space, nevertheless leading to an increase in pressure in it, is, apparently, the basic process that provides the “self-preservation” of methane hydrates.

Creep features and mechanism of active-layer detachment slide on the Qinghai-Tibet Plateau by InSAR

An active-layer detachment slide (ALDS) occurred on September 21, 2018, in the Fenghuoshan mountains of the Qinghai-Tibet Plateau (QTP) (34°39.1′N, 92°53.5′E). With the Sentinel-1A image from Copernicus Open Access Hub, we use small baseline subset to achieve the time series deformation map to analyze the thermo-spatial creep feature, motion pattern, trigger mechanism, and correlation of environmental changes in the ALDS. The SBAS (the Small Baselines Subset) results show that the trailing part of ALDS has the largest downward deformation rate; however, the leading area was small, and the creep feature shows a clear seasonal change corresponding to the freeze-thaw cycle. We also divide the motion pattern into three stages: moderate creep, steady creep, and rapid collapse, based on the deformation rate. Meteorological observation and reanalysis data, as well as borehole data, show that heavy precipitation in the summer of 2017 and 2018 promote the formation of underground ice, while high air temperatures allow the thaw plane to reach the ice-rich zone, and confined water generated by the two-way freezing process result in ALDS. Moreover, there exists a temporal delay of approximately one month in the association between deformation rate and both precipitation and temperature. Furthermore, there is a clear correlation between variations in thawing depth and deformation, which serves as the primary catalyst for ALDS in permafrost regions. Finally, we also identify that ALDS is a mixed-type landslide and that cumulative deformation and creep damage play the main roles in triggering ALDS.

Sea Coast of the Western Part of the Russian Arctic under Climate Change: Dynamics, Technogenic Influence and Potential Economic Damage

The Arctic coast dynamics has been an urgent problem over the last years, from both a practical and a fundamental point of view. In this research, for the first time for the Russian Arctic coast, we assessed the damage from the loss of territories in the western part of the Russian Arctic, where the active production and transportation of hydrocarbon material are carried out. Most of the studied coastline is composed of frozen unlithified soils with inclusions of underground ice. In this regard, the coastal zone is highly sensitive to climate change and its economic consequences. According to our investigation and literature data, the erosion rates could rich up to 2–3 m/year in some part of the coastline. Having estimated the cadastral cost of land and the area of the possible loss of territory, as well as the cost of transport infrastructure in the risk zone, we tried to predict the damage from changes in the total structure of the area under consideration. In particular, the economic damages from coastal permafrost processes were estimated. The assessment was conducted for the middle of the 21st century, taking into account the current climatic trend, erosion rate and probable maximum warming in this region.

Features of the formation of the coasts of Chukotka and the Koryak highlands

Long-term expeditionary studies of the Geography Faculty of Lomonosov Moscow State University of the Arctic coast of Russia (1969 – 2015) have provided extensive material on hydrology, channel morphodynamics and geomorphology of the estuaries of large rivers from the Northern Dvina to the Kolyma. The joint work of the Moscow State University and the M. K. Ammosov North-Eastern Federal University made it possible to signifiantly expand the geography of research to the coasts of the Chukchi and Bering Seas. Based on the analysis of geological and geomorphological data and an array of published and archival materials, it was possible to establish patterns and specifi features of coastal and estuarine processes in the fial phase of stabilization of the post-glacial ocean transgression. Over the past 7-5 thousand years, floding of low-lying hilly coastal plains, river valleys and fjords has occurred. The active impact of the wave activity of the sea led to the erosion of the upper part of the underwater slope, the restructuring of its profie and the retreat of accumulative forms towards the land and the creation of modern outlines of the coastline. The sections of the coast extended into the sea, composed by a thickness of loose quaternary sediments, were partially eroded by waves, and sediments were involved in longitudinal and transverse movements, forming braids and embankments, which led to a general alignment of the coastline. Currently, in conditions of rising sea levels, the general trend towards the restructuring of the underwater slope and the coastal zone persists and can be extremely dangerous for coasts composed of strongly icy sandy-loamy alluvial-lacustrine deposits. A further increase in global temperature will signifiantly soften the climate of the Arctic coasts, cause the degradation of permafrost, thawing of underground ice and accelerate the process of retreat of coastal abrasion ledges, the sea edge of river deltas. Taking into account the regional geological and geomorphological features of the coasts of the Chukchi and Bering Seas, it should be expected that a possible rise in sea level will lead to thawing and degradation of permafrost rocks and vein ice.

TYPOLOGY OF TERRITORIAL VEGETATION UNITS ON THE EXAMPLE OF THERMOKARST MASSIFS ON KOTELNY ISLAND (NEW SIBERIAN ISLANDS)

In the Arctic, permafrost and underground ice melting is one of the modern problems that requires constant monitoring. In the areas with spreading thick ice-wedge polygonal networks, the territories occupied by groups of mounds separated by trenches formed in the place of melted ice veins are a widespread result of thermokarst. The vegetation of such territories (referred to as massifs) is represented by territorial units of the first hierarchy levels with an intra- (mosaic of patches within communities) and supraphytocoenotic (micro- and mesokombinations: complexes, their aggregates and series) heterogeneity. The shape, size and vegetation of the mounds and trenches change under the influence of thermal denudation, and the vegetation of a whole massif also changes, so it can serve as an indicator of thermokarst intensity. The relief formed by thermokarst is typical of the landscapes of New Siberian Islands. According to the descriptions of 38 massifs made on Kotelny Island in 1974–1975, they were for the first time typified as territorial units of vegetation. In total, 7 types of massifs belonging to 2 classes are identified and characterized: baidzharakh massifs proper (with mineral mounds) and massifs with peat mounds (including 1 type of massifs). The first class comprises 2 groups of types: weakly differentiated massifs (microcombinations) and differentiated massifs (mesocombinations). In the first group, there are 2 types of massifs, in the second one – 4 types. Six distinguished types of baidzharakh massifs correspond to successive stages of massif transformation (a scheme is given). The heterogeneity of massif vegetation becomes more complicated with time, and becomes simpler again, when the massif is destroyed. Embryonal massifs are represented by microcombinations, a group of developed (differentiated) massifs – by mesocombinations, collapsing massifs – by microcombinations. The developed typology of the baidzharakh massifs as territorial vegetation units is convenient for practical work and using in monitoring and comparative assessment of thermokarst intensity in the Arctic areas with different flora and vegetation.

Distribution of pingos on Svalbard

The present study explores the formation, preservation and degradation of pingos in High Arctic environments, which are controlled by the interplay of permafrost, hydrology and climate conditions. The analysis of aerial and satellite images and digital elevation model data revealed 136 pingo mounds on Svalbard Archipelago. The pingos are distributed at elevations from 0 to 201 m above sea level (asl) with a median of 42 m asl. Of those, 44 pingos are found above and 92 below the maximum level of the respective local Holocene transgressions. All pingos were found in terrain favorable for the formation of hydrologically sourced open-system pingos. Based on published geological data, at least 55 pingos locate near geological faults that presumably allocate sub-permafrost waterflow feeding the pingos. With maximum and mean heights of 40 m and 9.4 m, respectively, Svalbard pingos generally have larger diameters and reach mean heights twice those found in other Arctic regions, such as the predominately closed-system pingos of Northern Alaska and the North-east Siberian lowlands. The comparison of aerial photographs of 1936–1938 with aerial photographs of 2008–2012 of Svalbard pingos exhibit no change in the general morphology of the pingos during the last about seven decades. There are exceptions - four pingos have formed on Little-Ice-Age (LIA) moraines following the local retreat of glaciers, and one pingo – the Riverbed pingo – formed in Adventdalen after 1936. The pingo growth once initiated is dynamic with height gains of up to 1 m annually, but obviously stops within several years or decades. Today, 21 pingos continue to show activity by the outflow at perennial subpermafrost springs. Dried thermokarst craters were found on top of 19 pingos of all sizes and geomorphological positions, while 11 water-filled craters were found only on large pingos with heights exceeding 12 m. Transitional landforms (flattop pingos and platforms) were identified. These landforms may point to underground ice intrusions that do not reveal themselves as classical pingo mounds.

Feasibility analysis of energy-saving potential of the underground ice rink using spectrum splitting sunshade technology

The original intention of skylights for underground ice rinks is to introduce natural light, but incoming solar radiation also affects the ice quality and ice-making energy consumption. As public sports and fitness venues of “Ice Cube”, sustainable operation of the underground ice rink with transparent skylights, has attracted much attention of architectural designers. To reduce the energy consumption without affecting indoor natural lighting, the heat transfer process of a skylight is discussed and modeled, and an advanced sunshade technology using Antimony Tin Oxide (ATO) nanofluids is proposed to filter UV/NIR and reserve visible light for indoor natural lighting. Meanwhile, two factors’ effects, including outdoor solar irradiation and mass fraction of ATO nanofluids on the energy-saving potential of an underground ice rink, are discussed, and results indicate that spectral energy of UV and NIR decreases by 23.16% and 32.99% respectively, with 20 ppm ATO nanofluids, but the energy during visible light region only reduces by 11.56%. Additionally, a high mass fraction lowers indoor solar radiation but also lifts artificial lighting energy consumption, and the mass fraction of 200 ppm is recommended as the optimal mass fraction with annual total energy consumption of 392 GJ.

RADIOCARBON CONSTRAINTS ON PERIODS OF POSITIVE CAVE ICE MASS BALANCE DURING THE LAST MILLENNIUM, JULIAN ALPS (NW SLOVENIA)

ABSTRACTCaves containing perennial ice deposits make up a little-known, but emerging part of the cryosphere under increasing scrutiny from the scientific community. M-17, a sag-type ice cave opening at 1879 m asl in the Tolminski Migovec massif of the Julian Alps (NW Slovenia) contains a perennial underground ice deposit whose paleoclimate sensitivity is poorly understood and whose longevity under current climate change is at risk. The past mass balance of this cave is constrained using wood macro-remains embedded in ice. Accelerator mass spectrometry radiocarbon dating of 18 wood samples embedded in ice provides the largest currently available dataset for a subterranean ice deposit in the southern European Alps. The reconstructed chronostratigraphy reveals three main phases of likely positive ice balance around 900–1100 AD, 1200–1300 AD, and 1700–1800 AD, as well as a period of negative mass balance around 1300–1400 AD. The onset of cave glaciation is deemed to have occurred no later than about 900 AD, with evidence of overall positive ice mass balance during multi-decadal periods characterized by cooler-than-average summers and wetter-than-average springs. Conversely, negative mass balance is recorded during a period warmer-than-average summers and dry springs. The cave has experienced ice mass loss since its discovery in the 1980s.

Approaches to the study of deformations in permafrost soils

The object of the study is the processes of metamorphism of frozen rocks, including structural restructuring, as well as plastic and brittle deformations of underground ice. In geocryology, many experts note the importance of considering the processes of deformation of frozen rocks. At the same time, the deformed rocks themselves do not stand out in a separate category, which makes it difficult to study the development of cryogenic geosystems after their formation. The main method used in this article is the analysis of the results of previous studies by various authors on the topic under consideration. The theoretical basis of the proposed approach is the provisions developed within the framework of the mechanics of frozen soils and structural ice science. The synthesis of the analyzed materials was carried out on the basis of a geosystem approach. In the proposed work, for the first time, a comparative analysis of structural deformations of various kinds of cryogenic formations was carried out. The relevance of the topic under consideration is due to the need to study the patterns of deformation of frozen rocks in natural conditions. Theoretically, this is important for a deeper understanding of the processes occurring in the cryolithozone. For practical purposes, work in this direction will allow us to more accurately assess the possibility of the development of dangerous engineering-geological processes with man-made impacts on frozen rocks. Changes in the structure of frozen rocks continue after the formation of the primary structure. Deformations, that is, violations of the primary addition, are an integral part of the structure of frozen rocks. Data on deformations of the primary cryogenic structure provide information about the history of the development of cryogenic geosystems that have already been formed. It is necessary to develop a classification of textural and structural deformations of the cryogenic structure of frozen rocks, in which a special type should be distinguished - metamorphosed ice formations. It is necessary to develop methods of structural and deformation analysis that allow establishing links between the observed deformations of the cryogenic structure and the processes occurring in frozen rocks.

Sentinel‐Based Inventory of Thermokarst Lakes and Ponds Across Permafrost Landscapes on the Qinghai‐Tibet Plateau

AbstractThermokarst lakes and ponds (hereafter referred to as thaw lakes) play an important role in the permafrost regions by regulating hydrology, ecology, and biogeochemistry. However, detailed quantitative information on thaw lake extent and distribution remains poorly resolved across the entire permafrost regions on the Qinghai‐Tibet Plateau (QTP). Here, we applied the random forest (RF) model and manual visual vectorization methods to extract thaw lake boundaries on the QTP based on Sentinel‐2 images. Accuracy assessment was comprehensively demonstrated regarding the inherent spatial resolution of imagery and RF model performance. The results showed that the accumulated uncertainty of the total thaw lake area was ±5.75 km2, and the mean accuracy (91.9%) from field‐measured boundaries of 132 thaw lakes supported the accuracy of this inventory. A total of ∼161,300 thaw lakes with sizes ranging from 500 m2 to 3 km2 were detected, with a total area of ∼2,825.45 ± 5.75 km2. Most thaw lakes were detected in the continuous permafrost type (94.1%) and within the elevations of 4,500–5,000 m (68.4%). The small thaw lakes (<10,000 m2) predominated the total lake number (78.9%) but contributed to a small portion of the total lake area (12.7%). Spatial distributions of thaw lakes in terms of different climatic and environmental conditions were also comprehensively explored, including temperature, precipitation, ground thermal stability, active layer thickness, vegetation, soil properties, and underground ice content. This inventory is expected to be incorporated into Earth system models for a more comprehensive projection of the large‐scale biogeochemical feedback of thermokarst landforms on the QTP under continued global warming.

Analysis of permafrost effect on water exchange processes

The article focuses on the importance of studying the water exchange role of the permafrost, which currently occupies a quarter of the Earth's land and is 1.5 km deep in some regions, as well as assessing the permafrost impact on the formation of surface and ground water resources and regime. First of all, the permafrost water exchange function is associated with the freezing of water-saturated rocks and thawing of ice-saturated ones. The author gives individual consideration to the water exchange role of the active layer and the effect of the permafrost long-term dynamics on water exchange direction and scale. The water exchange function of the active layer appears due to the seasonal phase transitions of groundwater from a liquid to a solid state and back. Thus, the volume of water formed by the thawing of underground ice accumulated in the active layer in winter has been estimated about 4·1012 m3. In this regard, it is proposed to give cryohydrogenic part associated with the seasonal transitions of groundwater from the liquid to solid state and back in the active layer of the cryolithozone independent consideration within the hydrological (climatic) cycle of the natural water circulation. It is most certain that the permafrost water exchange function is more significant being associated with longterm permafrost development dynamics under the influence of periodic dramatic climate fluctuations. Thus, during the Holocene climatic optimum about 4.5·1015 m3 of underground ice was converted to the liquid phase. The intensity of water formed from the melting of this amount of ice inflowing its surface and underground reservoirs has been estimated about 820 km3 per year. This fact considered, the author proposes to consider the cryolithogenic part separately in the geological cycle of the natural water cycle.

Soil hydrological process and migration mode influenced by the freeze-thaw process in the activity layer of permafrost regions in Qinghai-Tibet Plateau

It hasn't yet fully understood the influence of freeze-thaw action on hydrological processes in the active layer of permafrost regions. So this article investigated one permafrost cross-section at the northern slope of Bayan Har Mountains in the Source Area of the Yellow River in Qinghai-Tibet Plateau. According to the data of field monitoring, seasonal variability of soil hydrological processes in the active layer of permafrost regions was studied and simulated by the freeze–thaw module of HYDRUS-1D software. The results show that: 1) The soil moisture and the suprapermafrost water-level are divided into four stages based on the freeze-thaw process. Rainfall infiltration is the main driving force of soil hydrological processes, and the freeze-thaw front are the main limiting factors. 2) The active layer thickness (ALT) is greater on the upslope than that on the downslope due to the influence of terrain slope. It leads to that the change variation of the soil moisture and the suprapermafrost water-level on the upslope is also more gently than that on the downslope. 3) Temperature is the key factor that affects soil hydrologic process of the active layer in permafrost regions. Soil temperature and soil moisture showed a significant exponential linear correlation at different depths. The relationship between soil temperature and suprapermafrost water level shows Boltzmann function relations. 4) Soil moisture has a downward migration trend after a freeze-thaw cycle. It will result in the formation of underground ice near the permafrost table. Driven by the temperature gradient, the unfrozen water in the active layer moves from bottom to top during the freezing stage.

НОВЫЕ ИЗОТОПНО-ГЕОХИМИЧЕСКИЕ ДАННЫЕ ПО ТЕРМАЛЬНЫМ ВОДАМ ТАЛЬСКОГО МЕСТОРОЖДЕНИЯ (МАГАДАНСКАЯ ОБЛАСТЬ)

In this paper, we summarize new data on the chemical and isotopic composition of thermal wa-ters of the Talskoye deposit in the Magadan Oblast. We were the first to obtain the data on the content of stable oxygen (δ18O) and hydrogen (δD) isotopes in thermal and background waters, as well as oxygen (δ18O) and carbon in bicarbonate ion (δ13C), even though this is the largest ex-ploited deposit of low-mineralized alkaline nitric thermal waters in the region. The thermal water is fresh (M = 980 mg/l), alkaline (pH = 8.9), hydrocarbonate-chloride-sulphate sodium with a high content of fluorine (up to 17 mg/l) and silicic acid (up to 152 mg/l). The deposit is fed by atmospheric precipitation; we did not find traces of melting underground ice supply. A sequential scheme for calculating the temperature of a deep reservoir was applied, which allowed the temperature of water formation to be constrained at 108 °C suggesting an input of fluids rich in potassium and sulfate ion.

Climate Change and Its Influence on the Active Layer Depth in Central Yakutia

Analysis of climatic conditions for the period of instrumental measurement in Central Yakutia showed three periods with two different mean annual air temperature (MAAT) shifts. These periods were divided into 1930–1987 (base period A), 1988–2006 (period B) and 2007–2018 (period C) timelines. The MAAT during these three periods amounted −10.3, −8.6 and −7.4 °C, respectively. Measurement of active layer depth (ALD) of permafrost pale soil under the forest (natural) and arable land (anthropogenic) were carried out during 1990–2018 period. MAAT change for this period affected an early transition of negative temperatures to positive and a later establishment of negative temperatures. Additionally, a shortening of the winter season and an extension of the duration of days with positive temperatures was found. Since the permafrost has a significant impact on soil moisture and thermal regimes, the deepening of ALD plays a negative role for studied soils. An increase in the ALD can cause thawing of underground ice and lead to degradation of the ice-rich permafrost. This thaw process causes a change of the ecological balance and leads to the destruction of natural landscapes, sometimes with a complete or prolonged loss of their biological productivity. During this observation (1990–2018 period) the active layer of permafrost is characterized by high dynamics, depending on climatic parameters such as air temperature, as well as thickness and duration of snow cover. A significant increase in ALD of forest permafrost soils—by 80 cm and 65 cm—on arable land was measured during the observation period (28 years).

Theoretical substantiation of the hypothesis on the nature of the formation of a cylindrical erup

Relevance of the work. Cryovolcanic phenomena in the permafrost zone of the Earth are at the very initial stage of study. Purpose of this paper is to form and study theoretical ideas about the nature and mechanism of formation of a cylindrical vent in order to obtain scientifically substantiated knowledge that can subsequently be useful in developing the methodology and content of field studies, laboratory experiments and predictive calculations. The implementation of this goal is based on the main working hypotheses of the formation of the studied cryogenic volcano and the cryogenic processes that caused it in the permafrost massif: gassing (gas saturation) associated with the existence of stratal underground ice and the response of permafrost to climate fluctuations; degassing, accompanied by pneumatic release of rock and ice to the adjacent territory. Attention is also drawn to a hypothesis based on the concept of the migration and accumulation of hydrocarbons in the permafrost strata as a result of macro- and micro-seepage of gases, leading to the formation of near-surface redox zones favorable for the biodegradation of hydrocarbons with the formation of secondary microbial gases, primarily, methane. Methodology of research provides for a comparative analysis of characteristics of the composition and properties of homogeneous elements of the object under study, identified as a result of primary measurements and visual examinations and presented theoretical hypotheses. Results of work and scope of their application made it possible to reveal the theoretical prerequisites for substantiating the hypothesis about the complex nature of the formation of a cylindrical vent of a cryogenic volcano, which is expressed by a combination of long-term mechanical and thermobiochemical processes in permafrost. Conclusions. The authors put forward a hypothesis about the significant contribution of biochemical processes with the participation of hydrocarbons, including in the liquid phase, in the formation of a primary cavity (vent) of a regular cylindrical shape in the rock mass at the stages preceding the explosive outburst of crater rocks. As an interconnected one, the authors theoretically substantiated the hypothesis of the formation of a meromictic reservoir with an established unmixed stratified anaerobic deep part in the cryovolcano vent after the explosive destruction of the heaving mound. An explanation of the nature of the source of gas ignition (from a spark formed during the collision of solid rock fragments at the time of cryovolcanic outburst of rocks), as well as the ferroelectric effect that occurs during deformation of frozen rocks is presented. Keywords: permafrost, ice, permafrost mound, cryovolcanism, vent, thermobiochemical process.

Future projection of greenhouse gas emissions due to permafrost degradation using a simple numerical scheme with a global land surface model

The Yedoma layer, a permafrost layer containing a massive amount of underground ice in the Arctic regions, is reported to be rapidly thawing. In this study, we develop the Permafrost Degradation and Greenhouse gasses Emission Model (PDGEM), which describes the thawing of the Arctic permafrost including the Yedoma layer due to climate change and the greenhouse gas (GHG) emissions. The PDGEM includes the processes by which high-concentration GHGs (CO2 and CH4) contained in the pores of the Yedoma layer are released directly by dynamic degradation, as well as the processes by which GHGs are released by the decomposition of organic matter in the Yedoma layer and other permafrost. Our model simulations show that the total GHG emissions from permafrost degradation in the RCP8.5 scenario was estimated to be 31-63 PgC for CO2 and 1261-2821 TgCH4 for CH4 (68th percentile of the perturbed model simulations, corresponding to a global average surface air temperature change of 0.05–0.11 °C), and 14-28 PgC for CO2 and 618-1341 TgCH4 for CH4 (0.03–0.07 °C) in the RCP2.6 scenario. GHG emissions resulting from the dynamic degradation of the Yedoma layer were estimated to be less than 1% of the total emissions from the permafrost in both scenarios, possibly because of the small area ratio of the Yedoma layer. An advantage of PDGEM is that geographical distributions of GHG emissions can be estimated by combining a state-of-the-art land surface model featuring detailed physical processes with a GHG release model using a simple scheme, enabling us to consider a broad range of uncertainty regarding model parameters. In regions with large GHG emissions due to permafrost thawing, it may be possible to help reduce GHG emissions by taking measures such as restraining land development.

Algorithm for processing and interpretation of ground-penetrating radar data in the study of permafrost geocryological structures

Relevance. Ground ice is one of unstable components of the cryolithozone and occupies 400–600 km3 in total. Changes in the conditions of heat transfer of ground ice under the influence of external or internal factors can lead to the formation of thermokarst sinkholes, solifluction mudslides, cryogenic landslides and other dangerous cryogenic phenomena in the frozen rock mass. Various methods are used to study underground ice. You can distinguish the method of GPR. Its advantages are efficiency and high detail of measurements. However, the process of identifying underground ice based on the results of processing and interpreting ground-penetrating radar data is currently not formalized in the form of an algorithm. Purpose of the work. Rapid mapping of geocryological structures requires the development of an appropriate algorithm (sequence of formalized procedures) for the processing and interpretation of ground penetrating radar data. Methodology of the algorithm is based on the analysis of characteristics of GPR traces, the use of fast Fourier transform to calculate the spectra of GPR traces and further analysis of the results. Results of the study. The developed algorithm will make it possible to quickly study the structural features of the frozen rock massif with the release of layer ice. The algorithm was tested on the results of physical and computer modeling of ground-penetrating radar measurements of rock mass with ice included. Conclusions. The use of algorithms for processing and interpretation of ground-penetrating radar data for the operational mapping of geocryological structures of frozen rock massifs makes it possible to reasonably and rationally apply a set of measures to prevent the occurrence of unfavorable geotechnical processes or to reduce economic losses when negative geocryological processes are activated.

Construction and operation of linear constructions at the polygonal land relief, in the conditions of distribution of permafrost soil

The purpose of this paper is a promising development of methods for the roadbed design in the conditions of polygonal terrain and the presence of underground ice (ice, formation and polygonal-vein underground ice) and the analysis of the perspective for the for railway construction Arctic Zone. The choice of a criterion is made, on the one hand, according to the to the data of daily survey practice and the relative ease of establishing indicators of natural conditions responsible for the development of subsidence, on the other hand, according to the most objective reflection of the conditions of the sedimentation process. As tools of engineering protection of an embankment body which is located in the territory of distribution of the polygonal relief (polygonal vein ice), it is offered to produce local thermal insulation of the soils of the foundation of the embankment body and the adjacent territory in order to preserve the ground ice in the frozen state.

Prospecting and Evaluation of Underground Massive Ice by Ground-Penetrating Radar

Data from geocryological studies of soil and rock massifs in permafrost zone are very important as a basis for predicting possible negative consequences associated with climate change. A promising technique for studying geocryological structures (various types of underground ice) is the ground-penetrating radar (GPR) method. This paper presents the applications of the GPR method to prospect and evaluate massive ice in a frozen rock mass. To study the features of GPR signals received during sounding of underground ice, a model of a single GPR trace for the structure “frozen rock-ice-frozen rock” was developed. As a result, regularities were established in the kinematic and dynamic characteristics of GPR signals at the upper and lower boundaries of massive ice, depending on its geometric parameters. The established features were confirmed by the results of computer and physical simulation of GPR measurements of a frozen rock mass model. The main result of the study was to obtain a set of criteria for identifying massive ice according to GPR measurements. The developed criteria will allow the use of GPR for a detailed study of the structure of permafrost rocks to prevent the development of dangerous cryogenic processes in undisturbed and urban areas of the Arctic.

Water Exchange in Small Riversheds With Severe Climatic Conditions During a Cold Period of a Year

Presented are the results of experimental studies into the interaction between the surface and subsurface water in 16 mountain river basins of East Sayan and Lake Baikal as carried out by the Irkutskbased Institute of Geography during 1984‒1990. The research program included regular measurements of the thickness, area and volume of the surface and underground ice along the entire length of the valleys, pressure in closed lenses of underground waters, daily measurements of water discharges and chemical composition throughout the channel network. It was found that at the end of winter about 80‒90% of the area of the valleys of the rivers under study are covered by aufeis and by the seasonal subsurface ice of a different genesis. Furthermore, about half the volume of the seasonal ice corresponds to the surface ice (river ice and aufeis), and the other half to the subsurface segregated and injection ice. It was further shown that the period of formation of the main bulk of ice begins and ends earlier in the sections closer to the mouth. The “wave” of maximum intensity of ice formation gradually moves the river upstream. The ice volume is the last to form in the upstream components of the river network. At this time, the ice formation of the other area of the watershed has terminated or its main part has formed already. A cryogenic barrage phenomenon occurs, as a result of which the channel network receives subsurface water which, under normal conditions, is not drained by the river. The winter river runoff increases from 50% in the sections close to the source to 5‒10% at the mouth of the river.