We present an innovative approach to understanding permafrost degradation processes through the application of new environment-based particle image velocimetry (E-PIV) to time-lapse imagery and correlation with synchronous temperature and rainfall measurements. Our new approach to extracting quantitative vector movement from dynamic environmental conditions that can change both the position and the color balance of each image has optimized the trade-off between noise reduction and preserving the authenticity of movement data. Despite the dynamic polar environments and continuous landscape movements, the E-PIV provides the first quantitative real-time associations between environmental drivers and the responses of permafrost degradation mechanism. We analyze four event-based datasets from an island southwest of Tuktoyaktuk, named locally as Imnaqpaaluk or Peninsula Point near Tuktoyaktuk, NWT, Canada, spanning a 5-year period from 2017 to 2022. The 2017 dataset focuses on the interaction during a hot dry summer between slope movement and temperature changes, laying the foundation for subsequent analyses. In 2018, two datasets significantly expand our understanding of typical failure mechanisms in permafrost slopes: one investigates the relationship between slope movement and rainfall, while the other captures an overhang collapse, providing a rare quantitative observation of an acute landscape change event. The 2022 dataset revisits the combination of potential rain and air temperature-related forcing to explore the environment-slope response relationship around an ice wedge, a common feature of ice-rich permafrost coasts. These analyses reveal both a direct but muted association with air temperatures and a detectable delayed slope response to the occurrence of rainfall, potentially reflective of the time taken for the warm rainwater to infiltrate through the active layer and affect the frozen ground. Whilst these findings also indicate that other factors are likely to influence permafrost degradation processes, the associations have significant implications given the projections for a warmer, wetter Arctic. The ability to directly measure permafrost slope responses offers exciting new potential to quantitatively assess the sensitivity of different processes of degradation for the first time, improving the vulnerability components of hazard risk assessments, guiding mitigation efforts, and better constraining future projections of erosion rates and the mobilization of carbon-rich material.

To ensure that public infrastructure can safely provide essential services and support economic activities in seasonal frost regions, the design of their foundation systems must be updated and/or adapted to the impacts of climate change. This objective can only be achieved, if the impact of global warming on the soil thermal behaviour in Canadian seasonal frost regions is well-known and can be predicted. In the present paper, the results of a modeling study to assess and predict the effect of global warming on the thermal regimes of grounds in three Canadian seasonal frost regions (Ottawa, Sudbury, Toronto) are presented and discussed. The results show that future climate changes will significantly affect the soil thermal regimes in seasonal frost Canadian areas. The simulation results indicated a gradual loss in the frost penetration depth due to the climate change, in the three representative sites. The frost period duration will be shorter due to climate change in the three selected regions and will completely disappear in Ottawa and Toronto. However, the impact of climate change would not appear clearly in the first 40 years up to 2060. The response of the ground to the effect of climate change is a function of the geotechnical characteristics of the ground and the climate conditions. The numerical tool developed and results obtained will be useful for the geotechnical design of climate-adaptive transportation structures in Canadian seasonal frost areas.

Global warming has led to increasing pile foundation deterioration in permafrost regions. Theoretical analysis and indoor model tests were used to analyse variations in the shaft resistance and ultimate bearing capacity (UBC) for various permafrost active-layer thicknesses (Z(a)). A relationship for atmospheric temperature, Z(a) and ground temperature was developed. The equivalent adfreezing force was used as an index to evaluate the degradation of pile foundation bearing behaviour and a theoretical model was established. Based on the theoretical degradation model and indoor experimental data, a model was established to reflect the deterioration of pile foundation bearing behaviour in warm permafrost regions. The model was verified using numerical simulations. The results showed that shaft resistance at the ultimate state can be divided into three stages (stable change, rapid increase and attenuation). The depth of the maximum values decreased from -0.40 m to -0.65 m with an increase in Z(a). The pile head load (Q) against pile head settlement (S) curves were divided into three stages (elastic stage, elastic-plastic and plastic). A greater Z(a) made the plastic stage of the Q-S relationship occur earlier, resulting in a gradual decrease in UBC. The degradation variable (D) of bearing behaviour showed rapidly and then slowly increasing deterioration. This study provides experimental support for clarifying the degradation mechanism of pile foundation bearing behaviour and a degradation model to consider and quantify the impact of climate change on pile foundations in degraded permafrost.

Most residential buildings and capital structures in the permafrost zone are constructed on the principle of maintaining the frozen state of the foundation soils. The changing climate and the increasing anthropogenic impact on the environment lead to changes in the boundaries of permafrost. These changes are especially relevant in the areas of piling foundations of residential buildings and other engineering structures located in the northern regions since they can lead to serious accidents caused by the degradation of permafrost and decrease the bearing capacity of the soil in such areas. Therefore, organization of temperature monitoring and forecasting of temperature changes in the soil under the buildings is an actual problem. To solve this problem, we use computer simulation methods of three-dimensional nonstationary thermal fields in the soil in combination with real-time monitoring of the temperature of the soil in thermometric wells. The developed approach is verified by using the temperature monitoring data for a specific residential building in the city of Salekhard. Comparison of the results of numerical calculations with experimental data showed good agreement. Using the developed computer software, nonstationary temperature fields under this building are obtained and, on this basis, the bearing capacities of all piles are calculated and a forecast of their changes in the future is given. To avoid decreasing the bearing capacity of piles it is necessary to prevent the degradation of permafrost and to supply the thermal stabilization of the soil. The proposed approach, based on a combination of the soil temperature monitoring and computer modeling methods, can be used to improve geotechnical monitoring methods.

Direct Current (DC) Resistivity and Induced Polarization (IP) response of six profiles were measured using the Gradient electrode configuration in Adventdalen, Svalbard, to characterise the near-surface stratigraphy of the soil and to account for geotechnical and environmental aspects of global warming in the arctic region. In addition, Wenner array data was collected for the selected profiles to examine its effectiveness as compared to the Gradient array, given the characteristics of the study site. Two commercial inversion software programs, Res2DINV and AarhusINV, were used for the inversion of the DC resistivity and IP data, to compare the software. Physical soil properties, including porosity, water saturation, water salinity, freezing temperature and grain size distribution, previously measured from samples retrieved from wells along the studied profiles, were integrated in this study to investigate the correlation with geoelectrical properties of the sediments inferred from the DC resistivity and IP data. Results from processing of the Wenner array DC resistivity data provided higher resolution as compared to the Gradient array data, especially from deeper parts of the models, due to its higher signal-to-noise ratio. The Wenner array data also indicated better inversion result for the IP data as distinctive anomalies were better indicated in data from Wenner array survey. The Wenner array data also provided a realistic trend for the anomalies, thanks to the symmetrical geometry of the electrodes during the survey, although at the cost of time and higher expenses. Inversion results proved that AarhusINV resolved the geometry of the subsurface layers with higher resolution compared with the Res2DINV. However, the two inversion algorithms use slightly different parameters for the processing and for presenting the results, thus only allowing qualitative comparison. Based on the interpretations of the DC resistivity and IP data, four distinctive zones were identified from the surface to the maximum depth of 26 m, consisting of (i) unfrozen active-layer-(silts and sands), with intermediate resistivity values 200-300 omega center dot m; (ii) frozen soil with 3-10 m thickness and resistivity values between 2500 and 5000 omega center dot m; (iii) unfrozen soil (cryopeg) with high salinity and low resistivity of 40 omega center dot m; and finally (iv) clayey unfrozen soil sediments with low resistivity ranging 10-20 omega center dot m, at depths between 13 and 26 m. The IP data allowed for the delineation of a low chargeability zone near the surface and a high chargeability zone at greater depth which denote the active layer, lower parts of unfrozen soil sediments and cryopeg respectively, within the top 10 m of the subsurface. The 3D subsurface model of the study area was created based on interpretations of the DC resistivity and IP data and was constrained by the description of the subsurface stratigraphy from nearby wells, which provided detailed information about the vertical stratigraphy of the study area. In addition, a good correlation was observed between the studied physical properties of the sediments and the DC resistivity data for the intersecting profile SVAER04, as the interface between high and low resistivity data at ca. 10 m depth coincided the sedimentary formation with intermediate-fine grain size, high porosity, high water saturation and high salt content. Our findings show that joint application of the geoelectrical surveys and laboratory analysis of soil samples are an efficient complement to each other. These methods can be used as an alternative to each other to investigate larger areas where achieving high resolution data is not necessary.