Monitoring changes in unfrozen water content with electrical resistivity surveys in cold continuous permafrost

Oldenborger, Greg A.; LeBlanc, A M

doi:10.1093/gji/ggy321

Cited by 65 publications

(52 citation statements)

References 56 publications

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“…We investigated several electrical petrophysical models, but the reliability of the time-average equation [linking the velocities with the volumetric fractions, Equation 2] was not explored. Other velocity models would also be worth to be investigated (e.g., Draebing and Krautblatter, 2012), especially models which are considering the velocity (and resistivity) as a function of temperature (Carcione and Seriani, 1998;Oldenborger and LeBlanc, 2018), which is quite relevant in a permafrost context, although potentially less relevant for the field sites presented in this study due to their small observed permafrost temperature range (∼2-3 • C).…”

Section: Petrophysical Modelsmentioning

confidence: 99%

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

et al. 2020

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Section: Petrophysical Modelsmentioning

confidence: 99%

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

et al. 2020

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“…Geoelectrical methods permit therefore to detect and follow both, ice melting (through the phase change from ice to water) and thawing (through the higher mobility of ions for higher temperatures) processes (Hauck, 2002;Oldenborger and LeBlanc, 2018). The considerable resistivity change during freeze and thaw processes is (in addition to the temperature dependence of electrical resistivity, Hayley et al, 2007;Oldenborger and LeBlanc, 2018) mainly a consequence of the inverse conductivity characteristics of ice (electrical insulator) and water (electrical conductor). ERTM adds a spatial dimension and it can detect changes occurring at temperatures close to the freezing point during the so-called zero curtain period (defined in 1990 by Outcalt et al), when temperature does not vary significantly.…”

Section: Introductionmentioning

confidence: 99%

“…Caterina et al (2017),Hilbich et al (2011),Oldenborger and LeBlanc (2018),and Supper et al (2014), we invert our data sets…”

mentioning

confidence: 99%

Mountain permafrost degradation documented through a network of permanent electrical resistivity tomography sites

Mollaret¹,

Hilbich²,

Pellet³

et al. 2018

Preprint

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Abstract. Mountain permafrost is sensitive to climate change and is expected to gradually degrade in response to the ongoing atmospheric warming trend. Long-term monitoring the permafrost thermal state is a key task, but it is problematic where temperatures are close to 0 °C. The energy exchange is indeed often dominantly related to latent heat effects associated with phase change (ice/water), rather than ground warming or cooling. Consequently, it is difficult to detect significant spatio-temporal variations of ground properties (e.g. ice-water ratio) that occur during the freezing/thawing process with point scale temperature monitoring alone. Hence, electrical methods have become popular in permafrost investigations as the resistivities of ice and water differ by several orders of magnitude, theoretically allowing a clear distinction between frozen and unfrozen ground. In this study we present an assessment of mountain permafrost evolution using long-term electrical resistivity tomography monitoring (ERTM) from a network of permanent sites in the Central Alps. The time series consist of more than 1000 data sets from six sites, where resistivities have been measured on a regular basis for up to twenty years. We identify systematic sources of error and apply automatic filtering procedures during data processing. In order to constrain the interpretation of the results, we analyse inversion results and long-term resistivity changes in comparison with existing borehole temperature time series. Our results show that the resistivity data set provides the most valuable insights at the melting point. A prominent permafrost degradation trend is evident for the longest time series (19 years), but also detectable for shorter time series (about a decade) at most sites. In spite of the wide range of morphological, climatological and geological differences between the sites, the observed inter-annual resistivity changes and long-term tendencies are similar for all sites of the network.

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“…The applications of ERT are diverse and include imaging temperature contrasts for geothermal (Hermans et al, 2012) or hydrological applications (Musgrave and Binley, 2011), mapping variation in saturation to make inferences about surface water infiltration (Daily et al, 1992) or water uptake by crops (Michot et al, 2003), and imaging conductive solutes for tracer tests (Singha and Gorelick, 2005), contaminant imaging (Chambers et al, 2006), and remediation (Oldenborger et al, 2007). Recent concerns about the impact of thawing permafrost on atmospheric CO 2 and CH 4 levels (Schuur et al, 2008), alpine slope stability (Noetzli et al, 2003), and infrastructure integrity (Greenslade and Nixon, 2000) have spurred the use of ERT in many frozen ground monitoring studies to map the distribution of permafrost (Lewkowicz et al, 2011; McClymont et al, 2013; Kneisel et al, 2014a) and image the evolution of frozen and unfrozen areas (Krautblatter and Hauck, 2007; Kneisel et al, 2014b; Oldenborger and LeBlanc, 2018). Interpreting resistivity data in terms of unfrozen water content has been a goal in many permafrost studies (Hilbich et al, 2008; Dafflon et al, 2016; Keating et al, 2018; Oldenborger and LeBlanc, 2018).…”

mentioning

confidence: 99%

“…Recent concerns about the impact of thawing permafrost on atmospheric CO 2 and CH 4 levels (Schuur et al, 2008), alpine slope stability (Noetzli et al, 2003), and infrastructure integrity (Greenslade and Nixon, 2000) have spurred the use of ERT in many frozen ground monitoring studies to map the distribution of permafrost (Lewkowicz et al, 2011; McClymont et al, 2013; Kneisel et al, 2014a) and image the evolution of frozen and unfrozen areas (Krautblatter and Hauck, 2007; Kneisel et al, 2014b; Oldenborger and LeBlanc, 2018). Interpreting resistivity data in terms of unfrozen water content has been a goal in many permafrost studies (Hilbich et al, 2008; Dafflon et al, 2016; Keating et al, 2018; Oldenborger and LeBlanc, 2018). Quantitative inferences about unfrozen water content require rock physics relationships among electrical resistivity, temperature, and liquid water saturation.…”

mentioning

confidence: 99%

Electrical Resistivity of a Partially Saturated Porous Medium at Subzero Temperatures

Herring

Cey

Pidlisecky

2019

Vadose Zone Journal

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Core Ideas We collected resistivity data at a range of temperatures and initial saturations. Archie's equation was modified to include temperature dependence below 0°C. Bulk resistivity was used to estimate unfrozen water content and fluid resistivity. At subzero temperatures, unfrozen water content is independent of initial saturation. Ion exclusion from ice explains the dependence of resistivity on initial saturation. Electrical resistivity tomography has been used in many frozen ground applications to delineate frozen and unfrozen areas of the subsurface and monitor changes with time. In these studies, the amount of unfrozen water remaining in the pore space at subzero temperatures is often a parameter of interest. To interpret resistivity data quantitatively in terms of unfrozen water content, it is necessary to establish a relationship between bulk resistivity, subzero temperature, and liquid water saturation. In the literature, a consensus has not been reached on the form of this relationship, and a better understanding of the mechanisms controlling the resistivity of frozen ground is needed. This study used a unique laboratory apparatus to collect electrical resistivity tomography data for a uniform porous medium at temperatures from −20 to 25°C for a range of initial water saturations. Archie's equation was modified to include the effects of temperature above and below 0°C. Resistivity data collected below 0°C were used to estimate temperature‐dependent liquid water saturation and fluid resistivity. The amount of unfrozen water remaining at a given temperature was not related to initial water saturation and was nearly identical for all initial saturations at temperatures below about −5°C. The dependence of resistivity–temperature curves on initial water saturation at subzero temperatures was caused by differences in fluid resistivity as a result of ion exclusion during freezing. The relationships established in this study provide insight into the physical mechanisms that govern the resistivity of porous media at subzero temperatures and a starting point for quantitative analysis of resistivity data collected in frozen ground.

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Monitoring changes in unfrozen water content with electrical resistivity surveys in cold continuous permafrost

Cited by 65 publications

References 56 publications

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

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

Mountain permafrost degradation documented through a network of permanent electrical resistivity tomography sites

Electrical Resistivity of a Partially Saturated Porous Medium at Subzero Temperatures

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