Seasonal Permafrost Research Articles

Prediction Model of Dynamic Resilient Modulus of Unsaturated Modified Subgrade under Multi-Factor Combination

The objective of this research is to solve the problem of the lack of prediction methods and basis for the long-term road performance of oil shale residue-modified soil in seasonally frozen regions. This paper summarizes and expands the resilient modulus prediction methods in the related literature. Based on the measured soil–water characteristic curve (SWCC) of the compacted modified soil and the trend characteristics of dynamic resilient modulus under freeze–thaw cycles, a semi-empirical prediction model is proposed. This model was used to quantitatively forecast the resilient modulus of unsaturated modified subgrade soil after the freeze–thaw cycle in a seasonal permafrost region. The applicability and accuracy of the method were verified by dynamic resilient modulus tests of the oil shale residue-modified soil under various freeze–thaw cycles and moisture content. The results show that the model has a high degree of fit to the experimental data and is more suitable for predicting the dynamic resilient modulus of modified soil under the change of moisture and the freeze–thaw cycle compared to the existing models.

Climatic influence on productivity of walking excavators and bulldozers in stripping in gold placer mining

The state and mineability of placer gold reserves and resources in the Russian Federation is reviewed. Judging from wide application of dragline excavators in peat cutting, it can be effective to use draglines in placer mining at depths up to 50 m due to the much lower cost of stripping compared to the other methods. In this case, it is possible to apply various schemes of direct dumping and wider employment of draglines in actual mining. It is noted that one of the highest influences on productivity of draglines and bulldozers during stripping is the presence of seasonal and perennial frost. Two groups of factors to decrease productivity of walking excavators and bulldozers at negative air temperatures are proposed. The conclusions are made about the difficulty of determining frozen ground cuttability due to the peculiarities of overburden sediment formation and because of deficient detailed studies into the properties of rocks, which govern their strength characteristics during freezing. The less labor-intensive method of calculating productivity reduction of walking excavators and bulldozers during stripping is proposed as the determination of hourly productivity reduction patterns by mathematical methods describing the random nature of phenomena, in particular, by the correlation method. The equations of the hourly productivity reduction of draglines and bulldozers depending on average monthly negative air temperature and the hourly capacity reduction factor as function of seasonal permafrost thickness and perennial permafrost cross-sections in overburden face are derived. It is noted that seasonal freezing governs reduction in productivity of excavators and bulldozers at the beginning of the warm period of the year until the permafrost is completely thawed. Stefan’s formula is suggested, according to which it is possible to calculate the depths of seasonal freezing of peat depending on the average monthly air temperature quite reliably.

Drying–Wetting Changes of Surface Soil Moisture and the Influencing Factors in Permafrost Regions of the Qinghai-Tibet Plateau, China

Soil moisture (SM), an important variable in water conversion between the atmosphere and terrestrial ecosystems, plays a crucial role in ecological processes and the evolution of terrestrial ecosystems. Analyzing and exploring SM’s processes and influencing factors in different permafrost regions of the Qinghai-Tibet Plateau (QTP) can better serve the regional ecological security, disaster warning, water management, etc. However, the changes and future trends of SM on the QTP in recent decades are uncertain, and the main factors affecting SM are not fully understood. The study used SM observations, the Global Land Evapotranspiration Amsterdam Model (GLEAM) SM products, meteorological and vegetation data, Mann–Kendall test, Theil–Sen estimation, Ensemble Empirical Mode Decomposition (EEMD), and correlation methods to analyze and explore the characteristics and influencing factors of SM change in different permafrost regions of the QTP. The results show that: (1) At the pixel scale, GLEAM SM products can better reflect SM changes in the QTP in the warm season. The seasonal permafrost region is closer to the real SM than the permanent region, with a median correlation coefficient (R) of 0.738, median bias of 0.043 m3 m−3, and median unbiased root mean square errors (ubRMSE) of 0.031 m3 m−3. (2) The average SM in the QTP warm season increased at a rate of 0.573 × 10−3 m3 m−3 yr−1 over the recent 40 years, and the trend accelerated from 2005–2020. In 64.31% of the region, the soil was significantly wetted, mainly distributed in the permafrost region, which showed that the wetting rate in the dry region was faster than in the wet region. However, the wetting trend does not have a long-term continuity and has a pattern of “wetting–drying-wetting” on interannual and decadal levels, especially in the seasonal permafrost region. (3) More than 65% of the SM wetting trend on the QTP is caused by temperature, precipitation, and vegetation. However, there is apparent spatial heterogeneity in the different permafrost regions and vegetation cover conditions, and the three factors have a more substantial explanatory power for SM changes in the seasonal permafrost region. With the global climate change, the synergistic SM–Climate–Vegetation effect on the QTP tends to be more evident in the seasonal permafrost region.

Effect of Glutinous Rice Slurry on the Unconfined Compressive Strength of Lime-Treated Seasonal Permafrost Subjected to Freeze-Thaw Cycles

It is important to account for the poor ecological environment of weak seasonal permafrost regions while developing a suitable ground improvement technique. As an organic non-polluting material, glutinous rice slurry improves the unconfined compressive strength of the soil through induction and synergy with lime. The Qinghai-Tibet Plateau has cold weather, large temperature differences between day and night, and a fragile ecological environment. Once damaged, it is extremely difficult to recover. This study investigates the effects of glutinous rice slurry on the unconfined compressive strength (UCS), failure mode, and microstructure of lime-treated seasonally frozen soil subjected to freeze-thaw cycles. Organic glutinous rice slurry with concentrations of 0, 2, 4, 6, and 8% was added to soil specimens that were treated with 10% lime and subjected to 0, 1, 3, 6, and 10 freeze-thaw cycles. In tests, the addition of glutinous rice pulp could increase the UCS of the soil by up to 40%. The first freeze-thaw cycle has the greatest impact on the UCS of the soil sample, with a decrease of 6–15%. Glutinous rice slurry can reduce the degradation effects of freeze-thaw cycles by increasing the contact area between soil particles. In a comprehensive evaluation under test conditions, a glutinous rice slurry concentration of 4% led to optimal results. It revealed the change characteristics of the microstructure under the action of freeze-thaw cycles, which has a good corresponding relationship with the macroscopic mechanical properties. The results can provide reference value for the application of glutinous rice slurry in the modification of subgrade soil in seasonal permafrost areas.

三江源地区季节冻土时空格局及影响因子

PDF HTML阅读 XML下载 导出引用 引用提醒 三江源地区季节冻土时空格局及影响因子 DOI: 10.5846/stxb202108172267 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 三江源国家公园联合专项（LHZX-2020-07）；第二次青藏高原科考项目（2019QZKK0105） Spatio-temporal pattern and influencing factors of seasonal frozen soil in the Three Rivers Source Region Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:根据三江源地区21个气象台站的最大冻土深度、气温、降水观测数据和欧洲中心再分析资料，利用旋转经验正交分解等方法对1981-1010年三江源地区季节最大冻土深度（MFSD）的时空分布特征进行了分析，并探讨了季节冻土与气候因子之间的关系，结果表明：（1）40年来三江源地区平均MFSD为136.66cm，空间分布呈现出以玛多站最大中心值（218.85cm），向四周递减的分布特征。（2）40年平均变率空间分布和旋转正交经验分解第一模态时间系数均表现出三江源地区MFSD呈现明显下降趋势，季节冻土层明显减薄，平均MFSD递减率为0.51cm/a。（3）表征热力状况的气候因子中，湿润指数、气温和降水是影响三江源地区季节冻土较为重要的气候因子。（4）三江源地区季节冻土的关键区在东北部，MFSD典型高值年有1983年等4个年份；典型低值年有1988年等7个年份。通过对500hPa位势高度场典型高值年、低值年合成分析，季节冻土典型高（低）值年，北半球500hPa位势高度场负（正）异常；同时，南亚高压负（正）异常，其范围偏小（大），强度偏弱（强），温度场中心温度更低（高），对应三江源地区应季节冻土更厚（薄）；研究结果可为三江源地区开展冻土保育、退化湿地修复、退化草地近自然恢复等生态环境保护治理技术研发和示范提供气象支撑，为揭示土壤-大气互相影响的机制，应对气候变化，建设三江源国家公园提供理论依据。 Abstract:In this paper, the observation data of maximum frozen soil depth, air temperature and precipitation of 21 meteorological stations in the Three Rivers Source Region and the reanalysis data of European Center (EC) were used. The temporal and spatial distribution characteristics of seasonal maximum permafrost depth (MFSD) in Three Rivers Source Region were analyzed by means of rotating empirical orthogonal function (REOF), and the relationship between seasonal permafrost and climatic factors was also discussed. The results showed:(1) the spatial distribution of average MFSD in the Three Rivers Source Region in recent 40 years showed that Maduo station was the maximum, decreasing in all directions, the maximum value in the center was 218.85 cm, and the average MFSD in the whole region was 136.66 cm. (2) The spatial distribution of average variability in 40 years and the first mode time coefficient of REOF showed that MFSD in the Three Rivers Source Region presented an obvious downward trend in recent 40 years, the frozen soil layer was obviously thinner, and the average MFSD decline rate in the whole region was 0.51 cm/a. (3) Among the themal climatic factors, the humidity index, air temperature and precipitation were the more important climatic factors affecting the seasonal frozen soil in the Three Rivers Source Region. (4) The key area of seasonal frozen soil in the Three Rivers Source Region was in the northeast, including 7 meteorological stations. The typical high value years of MFSD were 1983, etc. and the typical low years were 1988, etc. Through the composite analysis of 500 hPa potential height field typical high value years and typical low value years, in the typical high (low) value years of seasonal frozen soil, 500 hPa potential height field showed the negative anomaly, the range of South Asia high was smaller (larger), the strength was weaker (stronger), the temperature at the center of the temperature field is lower (higher), and the seasonal frozen soil was thicker (thinner). The research results can provide meteorological support for the research, development and demonstration of eco-environmental protection technologies such as permafrost conservation, degraded wetland restoration, degraded grassland near-natural restoration, reveal the mechanism of soil-atmosphere interaction in the Three Rivers Source Region, deal with climate change, and provide a theoretical basis for the construction of Sanjiangyuan National Park. 参考文献 相似文献 引证文献

Ways of solving the problems of rational nature management in the areas of alluvial deposits development

A characteristic feature of the developed placer deposits is that most of them (up to 90–95%) are hard to develop, and the sands included in them are hard to enrich, due to their location in the geographic and climatic zones with a harsh climate, where perennial and deep seasonal permafrost is widespread almost everywhere. About 40% of alluvial deposits are clayey, highly clayey or cemented. As a consequence, there are significant losses of the valuable component and a large negative impact on the environment, including due to repeated re–mining. The studies presented in this paper help to significantly reduce losses and increase the productivity of the dredge, thereby increasing metal recovery.

The Influence of Freeze-Thaw Cycles on Unconfined Compressive Strength of Lignin Fiber-Reinforced Loess

In the seasonal permafrost region with loess distribution, the influence of freeze-thaw cycles on the engineering performance of reinforced loess must be paid attention to. Many studies have shown that the use of fiber materials can improve the engineering performance of soil and its ability to resist freeze-thaw cycles. At the same time, as eco-environmental protection has become the focus, which has been paid more and more attention to, it has become a trend to find new environmentally friendly improved materials that can replace traditional chemical additives. The purpose of this paper uses new environmental-friendly improved materials to reinforce the engineering performance of loess, improve the ability of loess to resist freeze-thaw cycles, and reduce the negative impact on the ecological environment. To reinforce the engineering performance of loess and improve its ability to resist freeze-thaw cycles, lignin fiber is used as a reinforcing material. Through a series of laboratory tests, the unconfined compressive strength (UCS) of lignin fiber-reinforced loess under different freeze-thaw cycles was studied. The effects of lignin fiber content and freeze-thaw cycles on the strength and deformation modulus of loess were analyzed. Combined with the microstructure features, the change mechanism of lignin fiber-reinforced loess strength under freeze-thaw cycles was discussed. The results show that lignin fiber can improve the UCS of loess under freeze-thaw cycles, but the strengthening effect no longer increases with the increase of fiber content. When the fiber content is less than 1%, the UCS growth rate of loess is the fastest under freeze-thaw cycles. And the UCS of loess with 1% fiber content is the most stable under freeze-thaw cycles. The freeze-thaw cycles increase the deformation modulus of loess with 1% fiber content, and its ability to resist deformation is obviously better than loess with 1.5%, 2% and 3% fiber content. The fiber content over 1% will weaken the strengthening effect of lignin fiber-reinforced loess, and the optimum fiber content of lignin fiber-reinforced loess under freeze-thaw cycles is 1%.

A new seasonal frozen soil water-thermal coupled migration model and its numerical simulation.

In this paper, a mathematical model based on spherical differential unit cell is proposed as a model for studying seasonal freeze-thaw soil space infinitesimal differential unit cell. From this model, the basic equations of permafrost moisture and heat flow motion are directly derived, then the linked equations form the permafrost water-heat coupled transport model. On this basis, the one-dimensional seasonal permafrost water-heat transport equation is derived. The model reduces the original spatial three-variable coordinate system (parallel hexahedron) into a coupled equation with a single spherical radius (R) as the independent variable, so the iterations of the numerical simulation algorithm is greatly reduced and the complexity is decreased. Finally, the model is used to simulate the seasonal freeze-thaw soil in the ShiHeZi region of Xinjiang, China. The principle of the simulation is to collect the soil temperature and humidity values of the region in layers and fixed-points using a homemade freeze-thaw soil sensor, after that we solve it by numerical calculation using MATLAB. The analysis results show that the maximum relative error of the model we proposed is 4.36, the minimum error is 0.98, and the average error is 2.515. The numerical simulation results are basically consistent with the measured data, then the proposed model is consistent with the matching states of permafrost moisture content and soil temperature in the region at different times. In addition, the experiments also demonstrate the reliability and accuracy of the model.

Effects of biochar and straw application on the soil structure and water-holding and gas transport capacities in seasonally frozen soil areas

To explore the effects of different regulation modes on the soil structure and gas transport characteristics in seasonal permafrost regions, freeze-thaw cycles (FTCs) were used as boundary conditions and three typical soils on the Songnen Plain were used: black soil, baijiang soil and meadow soil. Four treatments were established: biochar addition (B1), straw addition (S1), biochar combined with straw addition (B1S1) and an untreated control (CK). The changes in the proportion of soil water-stable aggregates, total soil porosity (TP), soil water characteristic curves (SWRCs), soil dissolved organic carbon (DOC) and soil air permeability (PL) were analyzed. The results showed that biochar and straw influenced the structure of the three soil types. The proportions of large (2–0.5 mm) and medium (0.5–0.25 mm) aggregates increased significantly. The soil aggregate stability indexes of the treated soils were better than those of the CK, and the three-phase ratios of the treated soils were closer to ideal. The different treatments had particularly obvious effects on the black soil; the generalized soil structure index (GSSI) values reached 95.59, 94.36 and 98.74 in the B1, S1 and B1S1 treatments, respectively. An interaction effect was observed between biochar and straw. B1S1 had a stronger effect than the other treatments, and the soil water holding capacity was significantly improved (FC = 0.317 cm3 cm−3). Under the B1S1 treatment, the DOC contents in black soil, baijiang soil and meadow soil were 160.78 mg/kg, 272.828 mg/kg and 271.912 mg/kg, respectively. Moreover, biochar and straw combined effectively reduced PL fluctuations under FTCs and improved the long-term stability of the soil structure. These results can aid in rational straw and biochar use to achieve comprehensive agricultural waste utilization.

Influence of Groundwater in the Base of the Gas Pipeline During the Formation of Aufeis

Pipelines with a large length in permafrost areas pass through various water passages. In winter, due to various types of waters – underground, river, and lake (often ice has mixed nutrition) – we observe the formation of aufeis. When they repeatedly pour out onto the surface and layer by layer freezing, plane-convex ice bodies are formed – aufeis. The heat and mass transfer interaction of a gas pipeline with a frozen ground base is considered during the filtration of permafrost groundwaters. Numerical modelling was carried out taking into account the real thawing process – freezing of the pore solution in the temperature spectrum at various temperature regimes of filtration of permafrost groundwater. As a result of a numerical experiment, it was established that aufeis formation occurs in the second half of winter and has a warming effect. In the first half of the summer period, intensive thawing of aufeis is observed, and the dynamics of the depth of seasonal thawing occurs with some delay, but at the beginning of the winter period, it is restored, as in ordinary soil. Long-term seasonal filtration of groundwater with a natural temperature of the environment has a warming effect on the temperature regime of frozen rocks. Warming and increased water saturation of the frozen soil base are accompanied by negative seasonal permafrost processes.

Application of anchor grounding devices in territories where there are permafrost soils

The article identifies the factors that affect the electrical conductivity of the soil. The most common methods of implementation of the grounding system, used in cold regions in permafrost conditions, are considered. A new design of the anchor electrode has been developed to prevent the ejection of the ground rod due to the effect of frost heaving of the soil. This article aims to describe the factors that should be considered when planning a grounding system for permanent and temporary installations in regions where there are seasonal frosts and permafrost.

Using floristic gradient mapping to assess seasonal thaw depth in interior Alaska

AbstractQuestionsIs it possible to map floristic gradients in heterogeneous boreal vegetation by using remote‐sensing data? Does a continuous vegetation map enable the creation of a spatially continuous map of seasonal permafrost soil thaw depth?LocationBonanza Creek LTER, Fairbanks, Alaska, USA.MethodsVegetation records are subjected to an ordination to extract the predominant floristic gradient. The ordination scores are then extrapolated using Sentinel 2 imagery and a digital elevation model (DEM). As the relation between vegetation pattern and seasonal thaw depth was confirmed in this study, the spatial distribution of ordination scores is then used to predict seasonal thaw depth over the same area.ResultsThe first dimension of the ordination space separates species corresponding to moist and cold soil conditions from species associated with well‐drained soils. This floristic gradient was successfully mapped within the sampled plant communities. The extrapolated thaw depths follow the typical distribution along a topographical and geomorphological gradient for this region. Besides vegetation information also DEM derivatives show high contributions to the thaw depth modeling.ConclusionWe demonstrate that floristic gradient mapping in boreal vegetation is possible. The accuracy of the thaw depth prediction model is comparable to that in previous analyses but uses a more parsimonious set of predictors, underlining the efficacy of this approach.

Long-term ecological consequences of forest fires in the continuous permafrost zone of Siberia

Wildfires are an important factor in controlling forest ecosystem dynamics across the circumpolar boreal zone. An improved understanding of their direct and indirect, short- to long-term impacts on vegetation cover and permafrost–vegetation coupling is particularly important to predict changes in carbon, nutrient and water cycles under projected climate warming. Here, we apply dendrochronological techniques on a multi-parameter dataset to reconstruct the effect of wildfires on tree growth and seasonal permafrost thaw depth in Central Siberia. Based on annually-resolved and absolutely dated information from 19 Gmelin larch (Larix gmelinii (Rupr.) Rupr.) trees and active soil layer thickness measurements, we find substantial stand-level die-off, as well as the removal of ground vegetation and the organic layer following a major wildfire in 1896. Reduced stem growth coincides with increased δ13C in the cellulose of the surviving trees during the first decade after the wildfire, when stomatal conductance was reduced. The next six to seven decades are characterized by increased permafrost active soil layer thickness. During this period of post-wildfire ecosystem recovery, enhanced tree growth together with positive δ13C and negative δ18O trends are indicative of higher rates of photosynthesis and improved water supply. Afterwards, a thinner active soil layer leads to reduced growth because tree physiological processes become limited by summer temperature and water availability. Revealing long-term effects of forest fires on active soil layer thickness, ground vegetation composition and tree growth, this study demonstrates the importance of complex vegetation–permafrost interactions that modify the trajectory of post-fire forest recovery across much of the circumpolar boreal zone. To further quantify the influence of boreal wildfires on large-scale carbon cycle dynamics, future work should consider a wide range of tree species from different habitats in the high-northern latitudes.

The Dependence Between Shear Strength Parameters and Microstructure of Subgrade Soil in Seasonal Permafrost Area

Permafrost and seasonal permafrost are widely distributed in China and all over the world. The failure of soil is mainly shear failure, and the strength of soil mainly refers to the shear strength. The two most important parameters of shear strength are cohesion and angle of internal friction. In order to ensure the sustainability of road construction in seasonal permafrost area, the microstructure of subgrade soil was observed and analyzed. First, three subgrade soils with different plasticity indices were prepared for triaxial test and scanning electron microscope (SEM). Then, these specimens underwent freezing–thawing (FT) cycles and were obtained shear strength parameters by triaxial shear test. Next, the microstructure images of soil were obtained by SEM, and the microstructure parameters of soil were extracted by image processing software. Finally, the correlation method was used to analyze the dependence between the shear strength parameters and the microstructure parameters. Results revealed that subgrade soils with a higher plasticity index had higher cohesion and lower angle of internal friction. In addition, with the increase of the number of FT cycles, the diameter and number of soil particles and pores tend to increase, while the roundness, fractal dimension and directional probabilistic entropy of particles decreased. With the increase of the plasticity index, the particle and pore diameter decreased, but the particle and pore number increased. Besides, particle roundness had the greatest influence on the cohesion and angle of internal friction of shear strength parameters.

Improving Actual Evapotranspiration Estimation Integrating Energy Consumption for Ice Phase Change Across the Tibetan Plateau

AbstractPermafrost thawing over the Tibetan Plateau (TP) is a consequence of climatic warming, which will change local hydrological processes remarkably. Evapotranspiration (ET) is an important local hydrological process indicator that needs to be well quantified. Several methods have been applied to estimate the ET. However, energy consumed by thawing was neglected in ET estimation on TP. Here a simple but effective method was introduced to represent the energy consumption due to ice phase changes in the generalized nonlinear complementary principle. Our method improved ET estimation by 4.60–106.67% in the nonlinear complementary model, validated at five eddy flux observation sites. With the new formulation, we analyzed the spatiotemporal patterns of ET and their driving factors during 1961–2014. The spatial averaged ET was 294.21 mm/year and decreased from southeast to northwest areas, cocontrolled by precipitation (Pre) and net radiation (Rn); dominated by the Rn in the warm‐humid areas while by the Pre in the cold‐dry areas. The temporal pattern of ET over the TP showed an increasing trend during 1961–2014, with a rate of 0.38 mm/year. The variations in air temperature (Tair) and Rn could explain 79.1% of the temporal variations in ET over the TP during the past 54 years, indicating atmosphere demand is the dominant factor on ET temporal variation. We also found that permafrost thawing accelerated the ET increases in the last 15 years over the transitional permafrost and seasonal permafrost areas, suggesting that degradation and ablation of permafrost under climatic changes will lead to accelerated ET.

Influence of Cryogenesis on Soil Biota on the Example of the Southern Part of the Vitim Plateau

A distinctive paleogeographic situation in the southern part of the Vitim Plateau, Transbaikal region, has resulted in the formation of landscapes featuring numerous heaving mounds and thermokarst depressions. The cryolithozone reacts to climate warming by reducing its area, while the temperature and depth of seasonal permafrost thawing are increasing. A soil profile differentiation identified in the heaving mounds and thermokarst depressions has led to changes in morphological and physicochemical properties of soils, which caused, in turn, a response of the biota.

Monitoring of soil temperatur on permafrost in natural and anthropogenic disturbed conditions in the Tunkinskaya Depression

The territory of the study is the Tunkinsky intermountain basin (South-Western Baikal region, Republic of Buryatia) which belongs to the area of sporadic (island) distribution of permafrost. Soil temperature controls many biotic and abiotic processes in it, so it is important to monitor the freezing and thawing regimes in peat and mineral soils. The object of the study is coarse-humic cryogenic soils on sandy lacustrine-alluvial sediments. The first site was represented by natural coarse-humic cryogenic soils under spruce forest, while the second site was organized on the area where in 1960s the forest had been destroyed and the soils were ploughed. At the end of XX century, the arable lands were abandoned, and now they are covered with steppe grasses (the long fallow). Both sites are located on the permafrost. The atmospheric-soil measuring complex was used to study the state of both the perennial and seasonal permafrost at these two sites. The soil temperatures were measured in automatic mode with a time interval of 1 hour from July 1, 2013 to June 30, 2017 along the soil profile from the surface down to a depth of 320 cm. Anthropogenic interference on one of the sites resulted in changes in vegetation cover, the soil moisture as well as the morphological structure and granulometric composition of the upper part of the soil layer. This caused changes in the temperature regime of the permafrost and its degradation with lowering of its upper limit. The soil on the long fallow is better warmed up and cools down faster than it takes place under the spruce forest. As a result of this, the maximum annual temperature on the surface here is higher by 10 °C, while at a depth of 320 cm – by 5 °C, and the minimum annual temperature on the surface is lower by 7 °C, while at a depth of 320 cm – by 1 °C. On the anthropogenically disturbed area, the warm period (at the soil temperature above 0 °C) on the surface is, on the average, by 22 days longer than on the natural lot. These differences are observed at all depths. As a result, the perennial permafrost is retained under the spruce forest below 130 cm throughout the year (soil temperature −0.2 ÷ −0.9 °C), while on the fallow the zero isotherm during seasonal thawing falls much deeper 320 cm, and the soil in the layer of 240–320 cm warms up to 2–5 °C.

The influences of climate on runoff: a case study of four catchments in Western Siberia

Currently, dynamic processes, affecting runoff in catchments, are poorly understood. Among all the elements of water balance calculations, the streamflow is the most accurately measured and largely reflects the current moisture content of the active layer. Devices for automatic measurement of water level and temperature of soil, water and air were installed in four small catchments with different climatic conditions. The studied catchments are located in a zone of oligotrophic swamps of the southern taiga, a zone of hilly swamps of the forest-tundra, a foothill zone of the southern taiga, and a mountain-glacial basin. Runoff in the mountain-glacier basin is determined using an acoustic level meter of the water flow. As a result: Site 1) We have revealed a change in the water-physical properties of the active layer in the marshy catchment, which resulted from the 2012 drought; Site 2) We have shown the linkages of the moisture content of the soil above the water table with extreme water discharge in active watersheds; Site 3) The increase in autumn runoff is due to thawing of seasonal permafrost and snow-melt in the tundra; Site 4) In the mountain-glacier basin, our studies are at an initial stage.

Calculation and Interpretation of Ground Penetrating Radar for Temperature and Relative Water Content of Seasonal Permafrost in Qinghai-Tibet Platea

Due to the seasonal permafrost thawing, the Qinghai–Tibet Highway has a depression and instability of the roadbed. In order to obtain the ablation interface and water content characteristics of seasonal permafrost areas, non-destructive ground penetrating radars using electromagnetic wave detection methods are widely used. Regarding the imaging of the ablation interface in permafrost regions, this paper proposes a high-precision procedure for seasonal permafrost media using waveform difference analysis, electromagnetic wave attenuation attribute calculation and relative wave impedance conversion. It improves the resolution and division accuracy of the imaging. In addition, the study demonstrates a method to calculate the temperature and water content of the ablation zone by mining attenuation attribute, relative wave impedance attribute, absolute instantaneous amplitude attribute and the weighted average frequency attribute parameters under the constraints of the measured data. This method has high accuracy and high efficiency and can be used in the rapid calculation of temperature and water content of seasonal permafrost on the Qinghai–Tibet Highway.

Температурный режим торфяных олиготрофных почв лесостепи Западной Сибири (на примере Николаевского ряма)

Температурный режим торфяных олиготрофных почв лесостепи Западной Сибири (на примере Николаевского ряма)