A conceptual model for talik dynamics and icing formation in a river floodplain in the continuous permafrost zone at Salluit, Nunavik (Quebec), Canada

Abstract

Icing occurs each winter along the floodplain of the Kuuguluk River in the continuous permafrost zone at Salluit in Nunavik (Quebec), Canada. The source of successive water overflows which thicken and enlarge this ice cover over time is suprapermafrost groundwater discharging from a talik below the riverbed. Electrical resistivity tomography was used to delineate the talik, while water level and temperature dataloggers were used to assess the thermo‐hydraulic conditions of the riverbed. The mean annual riverbed temperature was 1.8°C in 2016 while the mean annual air temperature was −6.0°C. Hydraulic heads below the ice cover as high as 2.8 m and events of abrupt decreases in hydraulic head due to suprapermafrost groundwater overflow through cracks in the ice cover were monitored. An analytical solution based on beam mechanics theory was used to assess the water pressure‐induced stresses which are sufficient to fracture the ice cover. A detailed conceptual model of the talik and icing dynamics is proposed to explain the cryo‐hydrogeological processes taking place in this complex groundwater–river system. The groundwater pressure buildup in the talik during the winter is due to constricted flow of suprapermafrost groundwater in the talik. These results have implications for understanding the dynamics of river taliks and their use as potential water supplies in northern communities.

Three‐Dimensional Numerical Modeling of Cryo‐Hydrogeological Processes in a River‐Talik System in a Continuous Permafrost Environment

“…This simulated behavior, including converging flow toward the talik, and a downgradient constriction with an associated pressure increase in winter, is consistent with the conceptual model of Liu et al. (2021).…”

“…Moreover, in addition to some high frequency variation in hydraulic head, there is a steady increase in riverbed hydraulic head from 16.93 up to 18.88 m from 25 November 2015 to 15 January 2016 due to a thickening of the frozen riverbed and river ice cover which can withstand more water pressure over time. The high frequency variation is related to several ice cracking events where the water pressure is released and groundwater overflow occurs above the ice cover in the river floodplain (Liu et al., 2021).…”

“…Based on field observations and geophysical investigations, Liu et al. (2021) developed a 3D conceptual model of the Kuuguluk river‐talik system in the continuous permafrost zone to provide insight into the cryo‐hydrogeological processes taking place in this system. As shown in Figure 2, the model includes natural downstream narrowing along the river channel which is underlain by corresponding constrictions in the talik.…”

“…The river talik then becomes a confined tube‐like system which is no longer hydraulically connected to the riverbed, with groundwater flow constrained within the talik. Due to downstream narrowing of the river channel, groundwater pressure builds up at corresponding talik constrictions where the hydraulic head in the talik becomes high enough to fracture the frozen riverbed and ice cover (Liu et al., 2021). Thereafter, groundwater overflow occurs which contributes to icing formation and growth, and groundwater pressure in the talik is released.…”

“…As observed in the field, icing growth in the floodplain of the Kuuguluk River occurs during the winter following multiple events of groundwater overflow from the talik aquifer through fractures in the ice cover. As a first approximation to estimate the stresses induced in an ice cover due to increasing water pressure from below, Liu et al (2021) applied beam mechanics theory, considering the ice cover as a uniformly loaded thin plate with embedded edges. Their analysis showed that tensile stresses resulting from a 1 m increase in pressure can be sufficient to induce fracturing in a 1.5-m thick ice cover near the center of the Kuuguluk River.…”