| Title | Monitoring changes in unfrozen water content with electrical resistivity surveys in cold continuous permafrost |
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| Author | Oldenborger, G A ;
LeBlanc, A -M |
| Source | Geophysical Journal International vol. 215, issue 2, 2018 p. 965-977, https://doi.org/10.1093/gji/ggy321  Open Access |
| Image |  |
| Year | 2018 |
| Alt Series | Natural Resources Canada, Contribution Series 20170326 |
| Publisher | Oxford University Press (OUP) |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Province | Nunavut |
| NTS | 25N/10 |
| Area | Canadian Arctic; Iqaluit |
| Lat/Long WENS | -68.5622 -68.5458 63.7606 63.7567 |
| Subjects | surficial geology/geomorphology; environmental geology; geophysics; Transport; engineering geology; Nature and Environment; permafrost; thermal analyses; modelling; geophysical surveys; electrical
resistivity; ground temperatures; ground ice; groundwater movement; salinity; in-field instrumentation; climate, arctic; permafrost thaw; monitoring; Infrastructures; Airports; Data processing; Climate change; lacustrine veneer; glaciofluvial outwash
plain sediments; glaciomarine deltaic sediments; till blanket; Phanerozoic; Cenozoic; Quaternary |
| Illustrations | location maps; geoscientific sketch maps; photographs; profiles; plots; models; time series; cross-sections |
| Program | Climate Change
Geoscience Permafrost |
| Released | 2018 08 08 |
| Abstract | For permafrost, information on unfrozen water content is critical for thermal modelling, understanding permafrost evolution and for predicting thaw susceptibility for infrastructure. We utilize
electrical resistivity surveys for the detection and monitoring of unfrozen water content in cold continuous permafrost. We develop a data processing scheme based on a common subset of reciprocal measurements to filter data from irregular
acquisitions in variable environmental conditions to a standard noise level, such that models recovered from disparate data sets can be compared quantitatively. Using temperature-corrected post-inversion model differencing, changes in recovered
electrical resistivity models are used to calculate the relative change in unfrozen water content over common regions of high model resolution. The technique is applied to electrical resistivity data collected seasonally using a permanent electrode
installation in cold continuous permafrost alongside airport infrastructure in the Canadian Arctic. The number of healthy data decreases over the experiment duration, with a correlation between data quality and ground surface temperature. Using the
resistivity models, relative changes in unfrozen water content are estimated that are consistent with temperature records. Results are compared to an empirical temperature-dependent water content model obtained via calibrated thermal modelling at the
study site. When compared to the empirical model, the changes in resistivity overpredict the changes in unfrozen water content due to temperature-induced phase changes alone after one year of acquisition. Prevalent changes in unfrozen water content
occur in a zone below the active layer at temperatures of approximately 0 to -4.5 °C, and may be indicative of permafrost evolution involving ice formation or water movement over many months in moderately-saline permafrost beneath airport
infrastructure. |
| Summary | (Plain Language Summary, not published)
Permafrost is perennially frozen ground. Permafrost properties such as the amount of unfrozen water are critical for thermal modelling of the response of
permafrost to climate forcing, understanding contaminant flow and transport, or for predicting the behaviour of permafrost as an engineering substrate. We utilize geophysical surveys to monitor changes in unfrozen water content for cold continuous
permafrost at Iqaluit International Airport in the Canadian Arctic from 2012/08 to 2015/06. We develop a novel data processing scheme and calculate changes in unfrozen water content that appear consistent with temperature records and can be used to
monitor active permafrost processes and evolution. |
| GEOSCAN ID | 306428 |
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