Frozen Soil Layer Research Articles

Prediction of frozen soil layer and temperature profile in water saturated soil –Numerical analysis on the heat transfer problem including freezing and/or thawing of soil–

著者らはこれまでに飽和含水土壌の凍結速度に及ぼす土壌含水率，土壌の初期温度，凍結管冷却温度および土壌物性値などの影響について実験的に検討してきた1)。本論文では凍結や融解を含む土壌内の温度分布予測のための数値モデルを提案し，数値予測結果と模擬土壌を用いた実験データや実際の地盤凍結工法で測定された測温データと比較を行いモデルの妥当性を検証した。その結果，このモデルでは冷熱源または温熱源が複数存在する場合や土壌の熱物性値が局所的に変化する場合，さらに地下水流が存在する系についても解析が可能であることが明らかになった。また，土壌の初期含水率，初期温度および凍結管冷却温度が凍結現象に及ぼす影響について検討した結果，特に土壌の初期含水率や冷却温度は凍結速度に大きな影響を与えることがわかり，また凍結が進むと各凍結管から成長した凍土同士が連結することで未凍結領域の冷却速度が低下し，その後の凍土の発達に強く影響することが明らかとなった。

Comparison of Snowmelt Infiltration under Different Soil‐Freezing Conditions Influenced by Snow Cover

The depth of soil frost is decreasing in cold regions around the world as a result of climate warming. To evaluate the potential impacts of the reduction in frost depth on the hydrologic cycle, it is necessary to understand snowmelt infiltration processes in frozen soils. A field study was conducted at an agricultural site characterized by volcanic ash soil in Tokachi, Hokkaido, Japan, where frost depths have decreased significantly in the last 20 yr. Soil temperature, water content, matric potential, snow cover, and meteorological parameters were monitored to quantify snowmelt infiltration flux for four winters that had different snow and soil conditions. When snowmelt began, the soil frost was 0.1 to 0.2 m thick in two winters and was absent in two other winters, providing a unique opportunity to compare snowmelt infiltration under frozen and unfrozen conditions. Most of the snowmelt water infiltrated into the soil under both frozen and unfrozen conditions, indicating that the frozen soil layer did not impede infiltration. The lack of flow impedance in the frozen soil was partly due to relatively high air temperature and an absence of freeze‐back events during the snowmelt period. Furthermore, the temperature of the frozen soil layer was close to 0°C when the melt started, meaning that very little meltwater refroze in the soil before the temperature reached 0°C. The thick (>1 m) snow cover insulated the soil surface, allowing the frozen soil layer to warm up with the upward conduction of heat from the unfrozen layer below. These results indicate the importance of the interaction between snow cover and soil, which can be significantly affected by climate change.

Cover Crop Effects on Infiltration, Soil Temperature, and Soil Moisture Distribution in the Canadian Prairies

Excess root zone soil moisture resulting from annual precipitation in excess of crop water requirements negatively affects crop yields. A field study was conducted in the 2005 and 2006 seasons on sandy loam soils to investigate the influence of berseem clover (Trifolium alexandrium L.) cover crop in oats (Avena sativa L.) on soil temperature, infiltration, and soil moisture redistribution within the growing season and during the fall to spring seasons. A 4-year crop rotation experiment to investigate farming with fewer chemicals was used to grow oats in a no-till cultivation system with and without the cover crop. The total and unfrozen water contents were measured in the field using neutron moisture meter and time domain reflectometry, respectively, at 0.2-m intervals from the surface to 1.8-m deep, plus a 0.1-m measurement depth. The cover crop significantly reduced soil moisture during the growing season resulting in significantly lower biomass yields (6146 kg ha-1 combined biomass for oats and berseem clover, vs. 7327 kg ha-1 for oats alone). By mid-August 2005, the cover crop treatment had 34.6% lower water content (0.17 vs. 0.26 m3 m-3) within the 0.0- to 0.7-m root zone depth compared to the non-cover crop. During the fall, the soil profile in the cover crop treatment was 3C warmer, thus delaying soil freezing and leading to a shallower depth of the frozen soil layer (0.4 vs. 0.6 m) in March 2006. During the spring, the cover crop treatment warmed and thawed earlier enabling more snow melt infiltration and deep percolation. Areas experiencing excess soil moisture could use annual cover crops as a means for reducing excess soil moisture during the summer growing season and avoiding accumulation of soil moisture during the fall, winter and spring seasons.

Investigations on indoor radon in Austria, Part 1: Seasonality of indoor radon concentration

In general, indoor radon concentration is subject to seasonal variability. The reasons are to be found (1) in meteorological influence on the transport properties of soil, e.g. through temperature, frozen soil layers and soil water saturation; and (2) in living habits, e.g. the tendency to open windows in summer and keep them closed in winter, which in general leads to higher accumulation of geogenic Rn in closed rooms in winter. If one wants to standardize indoor Rn measurements originally performed at different times of the year, e.g. in order to make them comparable, some correction transform as a function of measurement time which accounts for these effects must be estimated. In this paper, the seasonality of indoor Rn concentration measured in Austria is investigated as a function of other factors that influence indoor Rn. Indoor radon concentration is clearly shown to have seasonal variability, with higher Rn levels in winter. However, it is complicated to quantify the effect because, as a consequence of the history of an Rn survey, the measurement season maybe correlated to geological regions, which may introduce a bias in the estimate of the seasonality amplitude.

Tomographic imaging of permafrost using three-component seismic cone-penetration test

We conducted seismic cone-penetration tests (SCPT) and tomographic imaging in a permafrost mound in northern Quebec, Canada, to study the cryostratigraphy and assess the seismic properties of permafrost at temperatures near [Formula: see text]. A swept impact source generating both P- and S-waves and penetrometer-mounted three-component accelerometers were used to acquire surface-to-depth first-arrival times as input to produce 2D images of P- and S-wave velocities. Based on the three-component accelerometer records and the propagation modes of body waves, the P- and S-wave first arrivals were detected and discriminated. The inversion of the first-arrival times was based on the simultaneous iterative reconstruction technique. The multioffset surface-to-depth geometry used in this study limits the lateral resolution of tomographic imaging. However, the vertical variation in seismic velocities in the permafrost mound shows good reproducibility and can be compared to the cone data. The gathering of cone data such as cone resistance, friction ratio, electrical resistivity, and temperature, along with the seismic velocities, provides new insights into the cryostratigraphy of permafrost. While the cone data are affected by the vertical heterogeneity because of the complex sequence of ice lenses and frozen soil layers of a few centimeters thickness, the smooth velocity variations of P- and S-waves characterized by a wavelength of a few meters depend on the bulk physical properties of permafrost. The P- and S-wave velocities varied from [Formula: see text] and from [Formula: see text], respectively, for a temperature range between [Formula: see text] and [Formula: see text]. At this temperature range, the variations in unfrozen water content are important and affect directly the seismic properties of permafrost. The decrease in P- and S-waves velocities in depth with the permafrost mound depends nonlinearly on the increase of unfrozen water content from 9% to 30% for a temperature increase from [Formula: see text].

The effect of frozen soil layer thickness on thermal emission at the wavelengths 3.6–11 cm

The results of experimental investigation of temporal dynamics of radiobrightness temperature at the wavelengths 3.6, 5, and 11 cm in the course of frost penetration and thawing are presented for the soils with different humus content. Using the method of simulating emission from a horizontally stratified medium, it is shown that radiobrightness temperature variation is related to changes in the frozen soil layer thickness. It is noted that that dielectric permittivity of the frozen layer at the temperatures around 0 °C is controlled by non-frozen bound water, whose content depends on the soil type. It is also underlined that in certain cases proper interpretation of the experimental data requires inclusion of the soil moisture motion towards the cold front into consideration.

Study on a new-styled measure for treating water leakage of the permafrost tunnels

Abstract The status of water leakage of Kunlun mountain tunnel on Qinghai–Tibet railway is introduced by the time step in this paper. Based on the status of water leakage, the reason of water leakage of the tunnel is analyzed. In the light of the principle of protecting the frozen soil layer from thawing, a new-styled measure for treating water leakage, filling the ripped stone layer, is presented, and the design of filling the ripped stone layer is made. According to the basic theories of heat transfer and seepage, considering the coupled effects of seepage field and temperature field, a three-dimensional calculational model of the coupled problem is given, the spatial domain finite element formulae of this problem are obtained by Galerkin method, the time domain finite element formulae are obtained by Crank–Nicholson method, the solution process is presented, and a computer program is written. Using this model and program, three-dimensional nonlinear analyses for the coupled problem of seepage field and temperature field of the flat buried part from DK977+578 to DK977+682 in Kunlun mountain tunnel on Qinghai–Tibet railway are made under the two conditions of filling the ripped stone layer and not filling the ripped stone layer. The results show that it is feasible that the ripped stone layer is used for preventing water leakage of the permafrost tunnels. So, a new-styled measure can be used for treating water leakage of the permafrost tunnels.

Dissolved Organic Carbon in Upland Forested Watersheds Underlain by Continuous Permafrost in Central Siberia

Hydroclimatic variability and plant species ecology cause mosaics in forested watersheds in permafrost zones. Measurements of organic matter accumulation, stock of dissolved organic carbon (DOC), DOC concentrations in litter leachates, subsurface flow, stream and seasonal and annual export were made in two contrasting slopes and valleys in the northern taiga of Central Siberia. Increased organic carbon accumulation in litter was found in poor hydroclimatic conditions of the north-facing slope and bottom valleys. In contrast, DOC contents and its export to soil were almost two-fold higher in warmer well-drained sites of the south-facing slope. The overall DOC flux to mineral soil from the beginning of June to mid-September was 17 g C m−2 in the south-facing slope sites and only 9 g C m−2 in the north-facing slope sites. DOC export was positively correlated with precipitation stimulating leaching of mobilizable organic matter. Accordingly intra-seasonal and inter-annual variability of the DOC fluxes was tightly coupled with water input. Meanwhile DOC export in Sphagnum and feathermoss sites showed different behavior in dry and wet years. The presence of permafrost preventing deep seepage of organic solutes results in higher stream DOC fluxes compared to permafrost-free or island permafrost regions. However, thawing of seasonally frozen soil layer during the growing season led to the decreasing concentrations of DOC in the stream from June to September. For two seasons of continuous stream water sampling (June and August–September), the riverine DOC flux constituted about 14% of DOC entering mineral soil on both slopes. The ratio of hydrologic DOC loss to NPP of larch forests of the region was estimated to be 1.1%.

Monitoring over‐winter soil water dynamics in a freezing and snow‐covered environment using a thermally insulated tensiometer

AbstractWater potential below a frozen soil layer was continuously monitored over an entire winter period (using thermally insulated tensiometers sheltered in a heated chamber) along with other soil, snow and atmospheric variables. In early winter, the freezing front advanced under a thin snow cover, inducing upward soil water flow in the underlying unfrozen soil. The freezing front started to retreat when the snow cover became thick enough to insulate the soil, resulting in the reversal of the flow direction in the unfrozen zone. These data provide a clear illustration of soil water dynamics, which have rarely been monitored with a tensiometer. Copyright © 2005 John Wiley & Sons, Ltd.

Micrometeorological Conditions and the Thermal and Moisture Characteristics of Seasonally Frozen Soil in Eastern Hokkaido - New Comprehensive Hydro-meteorological Observation System for Atmosphere-snow-frozen Soil Interaction -

We constructed a new comprehensive hydro-meteorological observation system to monitor atmosphere-snow-frozen ground interaction in Memuro, Tokachi, Hokkaido in October 2001. The system consists of atmosphere parts (temperature, humidity, wind speed, precipitation, radiation), soil parts (vertical temperature and unfrozen water content profiles, surface soil heat flux etc) and snow parts (snow depth, snow temperature profile, snow water equivalent ). Moreover, we developed new methods for measuring soil water potential under a frozen soil layer by using thermally insulated tensiometers, and for estimating evaporation from bare soil by water balance analysis using soil-moisture profile, rain gauge, and a small lysimeter without needing micrometeorological flux measurements. During the October 2001- October 2002 study period, (1)The soil moisture regime in winter was more dynamic than in other seasons. The minimum soil moisture (unfrozen water content) occurred during soil freezing periods and the maximum soil moisture occurred during snow melt even though winter precipitation was lower than summer precipitation. (2)The evaporation rate from bare in spring was generally higher than that in summer even though the air temperature in spring was lower than in summer. This is because net radiation, soil moisture and wind speeds in spring were higher than those in summer.

Hypothesis Concerning Distribution of Normal Forces of Frost Heaving across the Lower Surface of Solidly Frozen Soil Layers beneath Foundations

Existing schemes of interaction between heaving soils and immovable foundations are analyzed. Individual deficiencies are noted for use of results of these investigations in determining the uplift of shallow foundations on heaving soils, and the possibility of determining additional forces in foundations subject to nonuniform heaving of soil. A hypothesis regarding the distribution of normal forces induced by frost heaving against the lower surface of solidly frozen layers of soil beneath foundations with allowance for their strength and observance of equilibrium between the loads on the foundations and the normal forces induced by frost heaving, and also an engineering method for their determination are proposed.

Thick ice layers in snow and frozen soil affecting gas emissions from agricultural soils during winter

We investigated soil and snow cover gas concentrations at two agricultural sites (St‐Lambert; Chapais) in Quebec, Canada, during winter 1998–1999. Both sites showed frozen and unfrozen soils and complex snow cover structure. At St‐Lambert we measured higher average concentrations of N2O (35 to 62 μl L−1) and CO2 (3 to 19 mL L−1) below the frozen soil surface of plots subjected to a treatment of pig slurry than in the control plot (N2O, 9 to 30 μL L−1; CO2, 3 to 7.5 mL L−1). The lack of vertical gaseous concentration gradients in the snowpack was due to the trapping of accumulating gas below the impermeable frozen soil layer. Soil gas concentrations decreased sharply when soil warmed to the freezing point. At the same time, the snow cover was isothermal. N2O could have been lost at spring thaw through gaseous emissions and/or dissolved in meltwaters and leached to the drainage system. High N2O fluxes were measured using closed chambers (215 ng m−2 s−1, slurry treatment; 55 ng m−2 s−1, control) as soon as snow ablation was completed, but became negligible 2 days later, suggesting that emissions were the result of passive degassing rather than of increased biological activity. At Chapais, N2O and CO2 accumulated in the unfrozen soil surface below a thick (0.1 m) basal ice layer. The basal ice layer and the continuous ice layer above it were impermeable to gas diffusion, as demonstrated by the accumulation of a tracer gas (Ar, >50 mL L−1) introduced by a diffuser into the soil. The existence of a basal ice layer is uncommon in eastern Canada. The occurrence of such a phenomenon may increase with climate change due to more frequent rain events during the cold season and affect the dynamics of winter gas emissions from soils.

Spatial and Temporal Variations of Frozen Ground and Snow Cover in the Eastern Part of the Tibetan Plateau.

The observations of frost depth and snow water equivalent were carried out at Lhasa, Rikeze and Nagqu in the eastern part of the Tibetan Plateau from July 1993 to March 1999. Also, the routine data at the ten meteorological stations in the same part was analyzed, which covers the observation period. All the stations are located in the seasonally frozen ground region. The main results are as follows: The development of seasonally frozen ground was most remarkable at Nagqu, where the maximum frost depth was 160-200 cm. At Nagqu, the frost penetration began in October and continued until the middle of March. During the frost penetration, except in the midwinter, the soil layer near the surface froze in the night and melted in the daytime. At the thawing stage from April to May, the frozen ground melted from the surface and the frozen soil layer left underground became thin. The efficiency of frost penetration, α, under certain temperature conditions tends to increase with the altitude and the precipitation in the preceding autumn, but α is not influenced by the snow cover. Exceptionally, α is large at Lingzi and Qamdo in spite of their low altitudes. This may be ascribed to the less solar radiation at these stations than other stations, which enhances the frost penetration. The maximum frost depth increases with the altitude except for Lingzi and Qamdo.The days of snow cover increases with the latitude, but long lasting snow cover is not usual. At Nagqu, where the days of snow cover is the second largest among the ten stations, the maximum snow water equivalent was 20 mm, the maximum snow depth was 9 cm and the mean snow density was about 0.2 g cm-3. inter-annual variation of the days of snow cover at Nagqu is almost similar to that at Sogxian. The localized negative correlation between the winter air temperature anomaly and the days of snow cover was found at Nagqu and Sogxian in the winter of 97/98, suggesting the albedo effect of snow cover. The correlation is positive between the precipitation is summer and the days of snow cover at Sogxian in the preceding winter, which apparently corresponds to the snow-hydrological effect. The warm (cold) winter tends to follow the wet (dry) summer with much (little) precipitation respectively. But the relationship between air temperature and precipitation in the summer is not clear.

FROZEN SOIL IMPACT ON GROUND WATER‐SURFACE WATER INTERACTION1

ABSTRACT: Ground water and surface water interaction in the prairie pothole region of the United States and Canada is seasonally dominated by the presence of thick, frozen soil layers that affect infiltration. During a spring thaw, the subsoil may remain frozen, preventing infiltration. The impact of the frozen soil layer on the timing of infiltration of depressional‐focused recharge to the ground water is not clearly understood. The objective of this paper is to relate changes in the water table during spring to changes in frost depth and soil water content. A depression and adjacent upland study site were instrumented with CRREL‐type frost tubes, neutron probe access tubes, and ground water monitoring wells. Increases in water table levels in a depression occurred before the frost layer decomposed and infiltrating water quickly formed a recharge mound. Water table responses at the upland site took place as two events. The first event was a gradual rise, probably caused by the lateral dissemination of the recharge mound. The second rise was a rapid rise coinciding with the decomposition of the soil frost layer. Because of the accumulation of surface water in depressions, agricultural practices that remove water from a field can affect water resources management by limiting the addition of water recharge to unconfmed ground water.

An analysis of anomalous weather and climate around the M S=6.2 earthquake of Zhangbei region

Through analysis we found that some mesoscale anomalous regions (101–102 km) of meteorological parameters such as the special drought areas, unusual warm areas, the largest snowfall center, low pressure area together with the epicenter area of MS=6.2 Zhangbei earthquake on January 10, 1998 are located at the same area, i.e. there appears the “Five areas corresponding” phenomenon. Meanwhile, three times of low pressure evolution are generated and develop in the earthquake area in five days after the occurrence of the earthquake. The abnormal variation of the lower limit of frozen soil layer shows indirectly that unusual warm in earthquake areas are related to the upward thermal conduction from the deeper layer of earth surface.

Monitoring Winter Freezing in a Silt Soil in Southern Manitoba, Canada Using Surface DC Resistivity Soundings

The sensitivity of the electrical conductivity of soil to the temperatures just beneath 0 °C allows the application of electrical geophysical methods for monitoring soil freezing. Surface DC‐resistivity soundings were performed over Winter 1996–97 to examine the electrical response of winter freezing of a silt soil in Winnipeg, Manitoba, Canada (49 °48′30″ N, 97 °07′22″ W). Temperature measurements were made over a 2.7 m deep section during this time interval providing a semi‐continuous soil‐temperature profile. Additional geophysical measurements including seismic refraction, terrain conductivity, and time‐domain electromagnetics were completed to characterize the lateral and vertical variations in the soil properties. During the recordings the surface temperature in Winnipeg decreased from 5.6 °C in October to in January. The 0 °C isotherm reached a depth of 15 cm in mid‐November and a depth of 75 cm in late‐January. The freezing produced a two‐order of magnitude increase in the electrical resistivity of the soil which could be detected by Wenner DC‐resistivity soundings with electrode spacings of less than 3 m. Geophysical inversion of the resistivity soundings provides an image of the time‐varying electrical‐resistivity structure of the soil. When the frozen layer is modelled as a single layer of uniform resistivity, it increases in thickness from around 20 cm in December to 45 cm in February. These values represent estimates of the minimum thickness of the true layer. The resistivity of the frozen layer increases from in December when the average temperature of the frozen layer is to in February when the average temperature of the layer is This increase is probably due to increasing ice content in the layer. The results suggest the DC‐resistivity method provides a useful method for monitoring temporal and spatial changes in the frozen soil layer.

Geothermal modeling of soil or mine tailings with concurrent freezing and deposition

A geothermal model is described that simulates simultaneous deposition, freezing, and thawing of mine tailings or sequentially placed layers of embankment soil. When layers of soil or mine tailings are placed during winter subfreezing conditions, frozen layers are formed in the soil profile that may persist with time. The following summer, warmer soil placement may not be sufficient to thaw out layers from the preceding winter. Remnant frozen soil layers may persist for many years or decades. The analysis is unique, as it involves a moving upper boundary and different surface snow cover functions applied in winter time. The model is calibrated based on two uranium mines in northern Saskatchewan. The Rabbit Lake scenario involves tailings growth to a height of 120 m over a period of 24 years. At Key Lake, tailings increase in height at a rate of 1.3 m/year. Good agreement between the observed position of frozen layers and those predicted by the model is obtained. Long-term predictions indicate that from 80 to 200 years would be required to thaw out the frozen layers formed during placement, assuming 1992 placement conditions continue. Deposition rates of 1.5-3 m/year give the largest amounts of frozen ground. The amount of frozen ground is sensitive to the assumed snow cover function during winter.Key words: geothermal, model, tailings, freezing, deposition.

Modelling vertical and lateral water flow in frozen and sloped forest soil plots

Snowmelt runoff from forest land is influenced by the spatial distribution of soil frost which depends on climatic conditions and stand structure. Snow and frost dynamics as well as near-surface runoff and liquid water content in the soil were measured for two years in two small plots located on a slope within a subalpine spruce stand. These measurements were used to calibrate the one-dimensional water and heat transport model SOIL by only fitting three snow- and two soil-related parameters. The simulated snow and frost dynamics agreed well with field data. The partitioning of snowmelt water into lateral runoff and vertical percolation at the snowpack bottom was best represented assuming that downward water flow through the frozen layers occurred not only in the liquid phase between soil particles and pore ice (low-flow-domain) but also as microscopic bypass flow in the previously air-filled macropores (high-flow-domain). Simulated near-surface runoff is very sensitive to the impedance factor accounting for a reduced upward water flow in frozen soil layers and also to the heat transfer coefficient controlling the refreezing of water infiltrating through the empty voids. The runoff dynamics differed only slightly when the model was driven by daily instead of hourly weather variables.

Relationships between soil properties and the soil atmosphere in Swedish forest soils

Concentrations of O2 and CO2 in 11 mineral and peat forest soils were related to physical, chemical and biological site variables by means of PLS modelling. Soil depth, volumetric water content, air‐filled porosity, soil temperature and soil respiration explained 66% of the spatial variation in gas concentrations, when all soils and depths were included. With the inclusion of complementary X variables, the model explained 76% of the Y variance. The X variables affecting gas transport in the soil explained more of both spatial and temporal gas variations than those affecting the biological activity. Much of the effect of water content originated in the early growing season and were conditioned by frozen soil layers, hampering the infiltration of water from snowmelt. Soil moisture, rather than temperature, thus regulates the apparent soil atmosphere variations in these forest soils of northern Sweden, where a temperate climate with cold and snowy winters and moist summer conditions prevails.

Studies of the soil atmosphere and related physical characteristics in peat forest soils

The soil atmosphere in forested peat soils with depths of 0.8–1.2 m was monitored regularly for 3 years. Samples from gas equilibration chambers were analysed for N 2, O 2, CO 4, CH 4, N 2O and Ne by gas chromatography. Short spring periods with simultaneous and rapid O 2 decrease/CO 2 increase were the characteristic features at a soil depth of 5 cm. They were the effects of perched water tables on frozen soil layers. The soil atmosphere composition at a depth of 20 cm was particularly variable in the poorly drained sites, where this soil depth was close to the alternating level of the groundwater. At a depth of 50 cm, CO 2 and CH 4 had minimum concentrations in early or mid-summer and maximum concentrations in the late autumn or early winter. The reverse pattern for O 2 was indicated, but was less clear. In individual profiles and on average, O 2 decreased and CO 2 increased with increasing depth, except during some transient periods in the spring. Medium (H6) humified, inadequately drained Sphagnum peat differed from well humified (H8), well-drained wood peat, in that it contained considerable concentrations of CH 4. Only very small concentrations were occasionally found in the humified wood peat and they did not increase when the groundwater level rose after clearfelling. The groundwater level rose after clearfelling on both types of peat. Concentrations of O 2 decreased and CO 2 increased in the topsoil, particularly in the medium humified and insufficiently drained Sphagnum peat. The soil atmospheres, as represented by mean concentrations and extreme concentrations at three depths during the growing season, were significantly different on all plots, including the parallel clearfelled and forested plots.