Estimation Of Ice Content Research Articles

Broadband spectral induced polarization for the detection of Permafrost and an approach to ice content estimation – a case study from Yakutia, Russia

Abstract. The reliable detection of subsurface ice using non-destructive geophysical methods is an important objective in permafrost research. The ice content of the frozen ground is an essential parameter for further interpretation, for example in terms of risk analysis and for the description of permafrost carbon feedback by thawing processes. The high-frequency induced polarization method (HFIP) enables the measurement of the frequency-dependent electrical conductivity and permittivity of the subsurface, in a frequency range between 100 Hz and 100 kHz. As the electrical permittivity of ice exhibits a strong characteristic behaviour in this frequency range, HFIP in principle is suitable to estimate ice content. Here, we present methodological advancements of the HFIP method and suggest an explicit procedure for ice content estimation. A new measuring device, the Chameleon-II (Radic Research), was used for the first time. Compared to a previous generation, the new system is equipped with longer cables and higher power, such that we can now achieve larger penetration depths up to 10 m. Moreover, it is equipped with technology to reduce electromagnetic coupling effects which can distort the desired subsurface signal. The second development is a method to estimate ice content quantitatively from five Cole–Cole parameters obtained from spectral two-dimensional inversion results. The method is based on a description of the subsurface as a mixture of two components (matrix and ice) and uses a previously suggested relationship between frequency-dependent electrical permittivity and ice content. In this model, the ice relaxation is considered the dominant process in the frequency range around 10 kHz. Measurements on a permafrost site near Yakutsk, Russia, were carried out to test the entire procedure under real conditions at the field scale. We demonstrate that the spectral signal of ice can clearly be identified even in the raw data and show that the spectral 2-D inversion algorithm is suitable to obtain the multidimensional distribution of electrical parameters. The parameter distribution and the estimated ice content agree reasonably well with previous knowledge of the field site from borehole and geophysical investigations. We conclude that the method is able to provide quantitative ice content estimates and that relationships that have been tested in the laboratory may be applied at the field scale.

Petrophysical Joint Inversion Applied to Alpine Permafrost Field Sites to Image Subsurface Ice, Water, Air, and Rock Contents

Quantification of ground ice is crucial for understanding permafrost systems and modelling their ongoing degradation. The volumetric ice content is however rarely estimated in permafrost studies, as it is particularly difficult to retrieve. Standard borehole temperature monitoring is unable to provide any ice content estimation, whereas non invasive geophysical techniques such as refraction seismic and electrical resistivity measurements can yield information to assess the subsurface ice distribution. Electrical and seismic data are hereby complementary sensitive to the phase change. A petrophysical joint inversion was recently developed to determine volumetric water, air, ice and rock contents from electrical and seismic data using a petrophysical model, but was so far only tested on synthetic data and one proof-of-concept field example. In order to evaluate its applicability on different types of permafrost materials and landforms (bedrock, rock glacier, talus slope), we apply this petrophysical joint inversion scheme to five profiles located in the northwestern Alps. The electrical mixing rule (Archie's second law) was hereby identified as a source of model uncertainty, as it applies only when the electrolytic conduction is the dominating process. We therefore investigate and compare four petrophysical models linking the electrical resistivity with the ground constituents: Archie's law, Archie's law with an additional surface conduction factor, a model considering only surface conduction, and the geometric mean model. In most cases, the three first resistivity relations yield largely comparable results, whose reliability is discussed. The geometric mean model better resolve high ice content, as it is less influenced by the ice-rock ambiguity. We perform a systematic analysis of the regularisation parameters and then evaluate our results with validation data including thaw depths and ice contents derived from borehole measurements. Geophysical surveys have generally a lower resolution than borehole data, but have the advantage of providing spatio-temporal information in 2D or 3D. The joint inversion results are in relatively good agreement with the validation data for all sites from ice-poor to ice-rich conditions, when choosing the most adequate resistivity model and porosity initial value. Additional forcing constraints (e.g. porosity range constraint) based on site knowledge can improve the model parameter estimation.

QUANTITATIVE ESTIMATION OF VOLUMETRIC ICE CONTENT IN FROZEN GROUND BY DIPOLE ELECTROMAGNETIC PROFILING METHOD

Volumetric estimation of the ice content in frozen soils is known as one of the main problems in the engineering geocryology and the permafrost geophysics. A new way to use the known method of dipole electromagnetic profiling for the quantitative estimation of the volumetric ice content in frozen soils is discussed. Investigations of foundation of the railroad in Yakutia (i.e. in the permafrost zone) were used as an example for this new approach. Unlike the conventional way, in which the permafrost is investigated by its resistivity and constructing of geo-electrical cross-sections, the new approach is aimed at the study of the dynamics of the process of attenuation in the layer of annual heat cycle in the field of high-frequency vertical magnetic dipole. This task is simplified if not all the characteristics of the polarization ellipse are measured but the only one which is the vertical component of the dipole field and can be the most easily measured. Collected data of the measurements were used to analyze the computational errors of the average values of the volumetric ice content from the amplitude attenuation of the vertical component of the dipole field. Note that the volumetric ice content is very important for construction. It is shown that usually the relative error of computation of this characteristic of a frozen soil does not exceed 20% if the works are performed by the above procedure using the key-site methodology. This level of accuracy meets requirements of the design-and-survey works for quick, inexpensive, and environmentally friendly zoning of built-up remote and sparsely populated territories of the Russian permafrost zone according to a category of a degree of the ice content in frozen foundations of engineering constructions.

Estimation of ice formation in mortar saturated with sodium chloride solutions

Frost damage of concrete is usually caused by ice expansion, therefore, the ice formation of NaCl solutions is of significant importance for predicting the mechanical degradation of concrete under the combined frost action and NaCl attack. In this study, the ice formation in cementitious materials saturated with different concentrations of NaCl solution is theoretically investigated first. Then the ice formation in mortar is further studied experimentally by electrical measurements. To estimate the ice amount based on the electrical measurements, the relationship between temperature, saturation degree, solution concentration and the electrical conductivity of mortar specimen is clarified. With regard to ice formation and salt crystallization during freeze-thaw, the ice content estimation model is proposed for mortar specimens. In addition, electrical response of meso-scale mortar specimens saturated with NaCl solutions with freeze-thaw cycles (FTCs) is measured. The electrical test results are interpreted with the proposed model and the ice formation is estimated with FTCs. The results from electrical measurements are compared with the theoretical calculations, and acceptable agreement is observed.

Estimation of Ice Content in Mortar Based on Electrical Measurements under Freeze-Thaw Cycle

Estimation of Ice Content in Mortar Based on Electrical Measurements under Freeze-Thaw Cycle

Geophysical estimation of shallow permafrost distribution and properties in an ice-wedge polygon-dominated Arctic tundra region

Shallow permafrost distribution and characteristics are important for predicting ecosystem feedbacks to a changing climate over decadal to century timescales because they can drive active layer deepening and land surface deformation, which in turn can significantly affect hydrologic and biogeochemical responses, including greenhouse gas dynamics. As part of the U.S. Department of Energy Next-Generation Ecosystem Experiments-Arctic, we have investigated shallow Arctic permafrost characteristics at a site in Barrow, Alaska, with the objective of improving our understanding of the spatial distribution of shallow permafrost, its associated properties, and its links with landscape microtopography. To meet this objective, we have acquired and integrated a variety of information, including electric resistance tomography data, frequency-domain electromagnetic induction data, laboratory core analysis, petrophysical studies, high-resolution digital surface models, and color mosaics inferred from kite-based landscape imaging. The results of our study provide a comprehensive and high-resolution examination of the distribution and nature of shallow permafrost in the Arctic tundra, including the estimation of ice content, porosity, and salinity. Among other results, porosity in the top 2 m varied between 85% (besides ice wedges) and 40%, and was negatively correlated with fluid salinity. Salinity directly influenced ice and unfrozen water content and indirectly influenced the soil organic matter content. A relatively continuous but depth-variable increase in salinity led to a partially unfrozen saline layer (cryopeg) located below the top of the permafrost. The cryopeg environment could lead to year-round microbial production of greenhouse gases. Results also indicated a covariability between topography and permafrost characteristics including ice-wedge and salinity distribution. In addition to providing insight about the Arctic ecosystem, through integration of lab-based petrophysical results with field data, this study also quantified the key controls on electric resistivity at this Arctic permafrost site, including salinity, porosity, water content, ice content, soil organic matter content, and lithologic properties.

Theoretical Model for Estimation of Ice Content of Concrete by Using Electrical Measurements

Ice content is an essential factor that affects the hydraulic pressure of cement-based materials during freeze-thaw cycles (FTC), especially for predicting life cycle of concrete structures. Since electrical resistivity of mortar is in close relationship with moisture content, it is possible to estimate the ice content based on conductivity change. This paper presents the method using electrical measurements to obtain the ice content and clarifies the combined effect of temperature and degree of saturation for electrical conductivity of concrete.

Soil ice content measurement using a heat pulse probe method

Liu, G. and Si, B. C. 2011. Soil ice content measurement using a heat pulse probe method. Can. J. Soil Sci. 91: 235–246. Measuring the volume-based ice content (θi) and thermal conductivity (k) of frozen soil is important for modeling energy and water balance of the earth's surface. The objective of this study was to examine whether a heat pulse probe (HPP) method can be used to measure soil ice content. To minimize ice melting, a heat pulse of duration of 60 s and strength of q′≈25 W m−1was used for a HPP in frozen sands at various temperatures (T). For a 60-s heating duration, we compared the infinite line source (ILS) solution and finite line source solution with the solution of finite sample size and finite line source through simulations. The simulation suggested that a 60-s heating duration for ILS can be used for long heater probes in infinite media, or short probes in finite size samples in containers made of thermally insulating materials. In this study, sands were packed in small containers with heat pulse probes and a 60-s heating duration, and ILS were used for ice content estimation. Our results suggest that the HPP method has limited use in frozen soil. For sands with a mean grain size of 0.41 mm and 2.13 mm, there were good agreements between the HPP measured and gravimetric θivalues at temperature below −22°C and −18°C, respectively. However, above these temperatures, ice melting was significant and would lead to overestimation of θi. The higher the initial temperature, the larger the overestimation of θi.

Use of dielectric spectroscopy to estimate ice content in frozen porous media

We investigate the use of dielectric spectroscopy to estimate ice content in frozen porous media. A dielectric mixing model was used to determine the volumetric fractions of the different phases, based on knowledge of the bulk and single‐phase dielectric permittivities. Measurement of the dielectric permittivities at two different frequencies with an impedance analyzer is required to infer ice content. One of the frequencies (25 kHz) has to be close to the relaxation frequency of ice; the other frequency (158 kHz or higher) must be well above the relaxation frequency of ice to obtain a different permittivity value of the ice phase. The theory was tested with three soil samples containing different amounts of clay. Dielectric permittivities of the soil samples were determined between 0.1 and 200 kHz, and in the temperature range of −30°C to +5°C. Ice content was successfully determined for a loamy sand sample. However, surface phenomena at low frequencies (such as double‐layer polarization, surface conduction, and Maxwell‐Wagner type effects) made ice content estimation using our proposed methods unfeasible in silty loam and clay samples, which had 13% and 46% clay by weight, respectively.

Geophysical detection and possible estimation of ice content in permafrost in northern Quebec

Permafrost in northern Quebec and eastern Canada differs in many respects from that in western Canada and Alaska. The permafrost in northern Quebec contains no massive ice, and the soil deposits in which it occurs are sparse, generally thin, and composed mainly of material of glacial origin (till).