NMR Can Measure Groundwater Directly – Even in Permafrost Environments

NMR Can Measure Groundwater Directly – Even in Permafrost Environments

In permafrost landscapes, the ground remains mostly frozen throughout the year and liquid groundwater only occurs in certain locations or during anomalously warm periods.

Understanding the spatial and temporal distribution of groundwater in these environments is extremely important as it can affect processes ranging from geotechnical soil stability to the release of greenhouse gases. In a warming climate, permafrost systems are undergoing especially dynamic change and are the subject of extensive research across many government and private institutions.

Nuclear magnetic resonance (NMR) is an especially useful technique in permafrost investigations because it is the only geophysical method that can directly and unambiguously identify unfrozen water. Ice shows no detectable low-field NMR response, so any water measured by surface-based GMR surveys or borehole Dart/Javelin surveys can be confidently associated with unfrozen groundwater and reliably quantified. These inhospitable study areas require reliable instrumentation that can operate in very low temperature conditions, while also enduring bumpy snowmobile and helicopter rides.

Elliot Grunewald, Alaska, April 2017

Customers have used the Vista Clara GMR and Dart NMR systems in permafrost zones from the suburbs of Fairbanks [Parsekian et al.] to the limits of Svalbard [Keating et al.], well into the Arctic Ocean.

Some specific examples are summarized below with links to the full articles.

Parsekian et al. used the GMR outside of Fairbanks to successfully locate and image “talik” features, isolated bulbs of thawed ground, often found in proximity to thermokarst lakes. [Stanford University and University of Alaska] Read full article here.

Keating et al. used the GMR in Svalbard where permafrost intersects the artic coastline.  Their work found evidence of unfrozen saline water distributed in a background of thick permafrost, a structure that has important implications for groundwater flow and greenhouse gas release.  [Rutgers University] Read full article here.

Minsley et al. used the Dart to investigate permafrost environments that had been previously impacted by forest fires. Their work showed that fires leave long-lasting scars on permafrost, with long-term impacts on thaw to depths of several meters. [USGS] Read full article here.

Terry et al. used the GMR outside of Toolik Field Station, AK to image groundwater in an “aufeis” environment where groundwater springs discharge water and heat deep in the heart of permafrost regions.  A crew of researchers from Vista Clara, USGS, and University of Alabama, traveled by helicopter each day to reach the remote aufeis location. Read full article here.

For more information about using NMR in permafrost environments, Contact Us here.