Hillslope hydrology in upland permafrost regions (e.g., Alaska, High Canadian Arctic, Russia, Antarctica) is often dominated by water tracks, zones of enhanced soil moisture in unchannelized depressions that concentrate water flow downslope. Continued warming of permafrost regions may alter hydrologic cycling, leading to increased frequency of extreme hydrologic events like drought and flooding and modification to biogeochemical cycles. It is therefore imperative to parametrize the role of water tracks in the hydrology of the permafrost environments. In this study, we synthesize uniting and distinguishing hydrologic characteristics of water tracks across permafrost regions and then examine water track seasonality, occurrence, and contribution to the permafrost hydrologic cycle using field observation, remote sensing, and numerical modeling for permafrost hillslopes on the North Slope of Alaska, USA. Results suggest that water tracks occur across climate and hydrologically disparate permafrost landscapes but have ubiquitous surface wetness, vegetation, and snow duration patterns that can be identified remotely using 3-m resolution PlanetScope imagery. Detailed field investigation from 2022-2024 of three study sites with ~20 water tracks and ~15 gullies suggests that water tracks are hydrologically distinct from larger, variably channelized hillslope features and require more precipitation and time to initiate discharge following rainfall events. Across these study sites, concentration-discharge relationships reveal that water tracks can exhibit drastically different dynamics of particulate and dissolved organic carbon export based on landscape attributes. Young water fraction analysis found that in 2023, 24–78% of runoff from the study sites was young water less than 35 days old during the observed summer thaw season, and model-estimated young water fraction increased by two-fold when factoring in the fall shoulder season. Geophysical investigations indicate the presence of buried ice wedges on the margins of studied water tracks, supporting the idea that water tracks may form from the coalesced drainage of patterned ground. Over time, these drainage patterns likely evolve and widen into present-day water tracks that act as flow conduits and discharge liquid water into the fall shoulder season after the adjacent hillslope has frozen. Our ongoing analysis explores how water track flow seasonality may influence observed ground collapse and mediate or enhance the permafrost-carbon feedback. 

How to cite: Evans, S., Godsey, S., Del Vecchio, J., Harris, R., Frei, R., Yokeley, B., Mohammed, A., Chew, C., Cusack, K., Ferm, E., Hatch, K., Matejowsky, G., Polk, R., and Culha, C.: The role of water tracks in permafrost hillslope hydrology, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7345, https://doi.org/10.5194/egusphere-egu25-7345, 2025.

Increasing temperatures are rapidly changing the Arctic ecosystem. Yet, we are missing a predictive understanding of the interactions within the bedrock to atmosphere column that are driving ecosystem evolution and carbon-climate feedback. A critical knowledge gap within these systems are the dynamics of surface water - groundwater interactions, and infiltration and groundwater flow processes, which drive permafrost thaw and biogeochemical processes. Geophysical techniques have been shown to be a valuable tool to assess the intermediate depths (1 - 10’s of m) that are particularly important to understanding the impact of climate change on permafrost thaw and related hydrological dynamics. In this study we highlight how automated geophysical monitoring can reveal rapid and heterogeneous changes in thermohydrological conditions that are characteristic for discontinuous permafrost systems.

Given the remote environment, we will first introduce the field setup that allowed us to acquire continuous data for over 4 years. We present the variations in ground conditions and associated changes in data quality, which highlight the expected poor data during the winter season, once the ground is frozen. Focusing on the monitoring data, we show that summer rainfall events drive distinct infiltration patterns at locations of a deep active layer. Snowmelt and rainfall events drive considerable variations in groundwater level, which are confirmed by borehole information and driven by flow below the permafrost. Data acquired in early winter shows spatially heterogeneous ground freezing, mostly controlled by the microtopography. These observations provide novel information that will help in better understanding the complex hydrological processes taking place in discontinuous permafrost environments, and will eventually lead to better parameterization of ecosystem models.

How to cite: Uhlemann, S., Wang, C., Wielandt, S., Fiolleau, S., Ulrich, C., Shirley, I., and Dafflon, B.: Geophysical monitoring of hydrological dynamics within a discontinuous permafrost environment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12367, https://doi.org/10.5194/egusphere-egu25-12367, 2025.

Snow represents the single largest water source in most regions of the Arctic, but few investigations of snowmelt infiltration into frozen and unfrozen soils have been conducted in this region. To investigate the infiltration of snowmelt into tundra soils, we collected vertical soil cores before snowmelt (mid-April), mid-snowmelt (mid-May), and after snowmelt (early June) from Blæsedalen, Qeqertarsuaq (Disko Island), Greenland at sites varying in soil properties, snow depth, and landscape position. Soil cores were separated into sections, after which we measured bulk density, gravimetric water content (GWC), soil texture, organic content, and the water isotope composition of the soil water of each soil core section. Water isotope composition was also measured for vertically-integrated snowpack samples at each sampling location, so that we could attribute any changes in soil moisture to infiltrating snowmelt runoff. Post-snowmelt cores were separated into frozen and unfrozen sections, to compare the infiltration of snowmelt into frozen and unfrozen soil.

Initial results show that the GWC varied widely from 0.25 – 43 among soil core sections, the extremes reflecting differences between dense loamy soils with little organic material and porous, saturated peat. After snowmelt, soil water in the top 0 – 20 cm of the soil column experienced a significant shift towards the isotope composition of snow, regardless of whether the soil was frozen or not. There was little change in soil water isotope composition mid-snowmelt. Changes in GWC mirrored these results: the average GWC increased by 46% post-snowmelt in soil core sections from the top 20 cm of the soil column, with no significant change in GWC mid-snowmelt. Interestingly, frozen soils from the top 20 cm of the soil column experienced a larger increase in GWC than unfrozen soils, suggesting that frozen soils did not hinder the ability of snowmelt to infiltrate into soil. Below 20 centimetres in the soil column, no significant changes in water isotope composition or GWC were observed. We also observed no clear link between the snow water equivalent of the overlying snowpack, and the increase in GWC after snowmelt.

The landscape of Qeqertarsuaq is abundant with large snow drifts that last well into July, which could provide a significant source of water for soils downslope of drifts. We were unable to test this hypothesis because an exceptionally late snowmelt meant we collected post-snowmelt soil cores immediately after soils became snow-free, giving little time for lateral runoff from melting snow drifts to travel downslope. However, we did observe that peat soils, which develop in wet areas, were often present immediately downslope from large snow drifts, while only thin organic layers combined with other vegetation covers were present upslope of snow drifts. With this study, we have been able to provide the first insights into snowmelt infiltration on Qeqertarsuaq, and how it may be playing a role in the spatial variability of soil development.

How to cite: Wilcox, E. J., Plötz, H., Kaufmann, O., and Kutzbach, L.:  Investigating snowmelt infiltration into tundra soils on Qeqertarsuaq (Disko Island), Greenland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16642, https://doi.org/10.5194/egusphere-egu25-16642, 2025.

A fundamental research question of periglacial geomorphology is whether and how ground ice interacts with surface water flow to change grain-scale sediment transport dynamics, and how those processes translate to the landscape-scale, potentially changing the timing and intensity of erosion events. Polar deserts in the Canadian High Arctic serve as ideal field laboratories to isolate the effects of ground ice on particle transport due to a lack of vegetation and by being largely undisturbed since the last glacial maximum.

During the Summer 2024 field season at the Flying Squirrel polygon field on Devon Island, we observed a complex of pools interconnected by channelised polygon troughs and relatively steeper relict gravel deposits, as well as evidence of recent transport of gravel- and sand-sized particles. However, despite visiting during a storm event, we did not observe active transport and only limited surface water run-off. As such, the timing and magnitude(s) of the flow events  that caused the gravel deposits are unclear, nor do we know the thermal state of the bed during the time of transport. 

To investigate this research gap, we conducted flume experiments with an initially frozen bed under rarefied transport conditions to investigate at what thermal state sediment transport is favoured and compare the bed behaviour to unfrozen experiments. Particle flux is maximised at the start of the frozen experiments before decaying to an approximate steady-state background flux similar to the unfrozen experiments, following a power law with the relationship . At early stages of the frozen experiments, hydraulic jumps develop in concert with variations of the local thaw depth, which result in enhanced particle entrainment and relatively rapid thawing downstream, as the hydraulic jumps migrate upstream. Beneath hydraulic jumps, we observe forced injections of water into the partially-frozen bed, which can spread laterally along an evolving thaw front. Depending on the thaw front depth, the combined effects of locally-intensified melting, increased pore pressure and mechanical disruption of the bed can enhance particle entrainment locally and increase the overall erosion rate compared to unfrozen experiments. Enhanced rates of particle entrainment continue until hydraulic jump activity diminishes and the injected surface water no longer penetrates to the thaw front. Accordingly, we develop a maximum injection depth, which is strongly dependent on the local permeability, as well as the jump height.

Our experimental results show that the thermal state of the bed can have a strong influence on the local entrainment rate at the grain-scale with entrainment being promoted at a shallow thaw depth. We hypothesise that this sensitivity also translates to the landscape-scale, where all water has to travel as overland flow when the active layer is thin, whereas much of the water supply can be compensated as subsurface flow late in the summer, minimising particle entrainment. This could explain the lack of active erosion at the Flying Squirrel polygon field during the late summer when the active layer was approximately 1m deep.

How to cite: Eschenfelder, J., Chartrand, S., Jellinek, M., and Culha, C.: Where, when, and why do frozen landscapes erode faster than unfrozen ones?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7036, https://doi.org/10.5194/egusphere-egu25-7036, 2025.

The Arctic is rapidly changing due to increasing temperatures and hydrologic intensification. The Arctic is also data-limited, necessitating the development of new tools to document and quantify ecosystem responses to these changes. Some of the hardest changes to observe are in the subsurface, including thaw depth conditions in continuous permafrost regions. Thaw depth is dynamic across the thaw season as well as on a longer, interannual scale as the Arctic warms and permafrost degrades. Measuring thaw depth often requires intensive sampling or remote sensing capabilities that have spatiotemporal limitations; therefore, little is known about complex subsurface dynamics and how they will affect Arctic ecosystems in the future. Often, surface waters are our best proxy for subsurface dynamics, as streams integrate signals from the landscape as water travels through the hillslope subsurface. In permafrost systems, water and solute flowpaths are governed by thaw depth dynamics, and flowpaths through variable soil chemical conditions govern downgradient stream water chemistry. Hence, thaw depth may be reflected in stream chemistry. Prior work looking at long-term stream chemistry data suggests there are multiple soil-derived solutes that are tracers of thaw in Arctic catchments, and some increase with thaw over decadal timescales. Building on this work, we want to know if this stream chemical tracer approach works at different spatiotemporal scales, such as within a thaw season as thaw depth increases, and across catchments with varying characteristics (e.g., slope, vegetation). We hypothesize that with more frequent stream chemistry observations across a thaw season, we will also see these soil chemical tracers signal seasonal thaw, and that the signal’s strength will vary depending on catchment characteristics.  

To determine whether we can use chemical tracers as proxies of thaw depth across a diverse set of catchments on Alaska’s North Slope, we sampled the stream outlets of three catchments underlain by continuous permafrost across three thaw seasons (2021-2023). We measured continuous discharge and analyzed nine different ions including Ca, Fe, Na, and S to identify seasonal patterns in stream chemistry, as these element concentrations change with soil depth in this region. As discharge could impact instream solute concentrations, we also analyzed concentration-discharge relationships to determine whether discharge was significantly influencing concentration and reducing the tracer’s utility in signalling thaw depth.  

We found that the efficacy of the stream tracer approach to detect thaw on a seasonal scale is seemingly dependent on catchment characteristics, as we suspected. Our two low-gradient tundra systems did not show consistent patterns in the tracers; however, we saw patterns in multiple tracers in our high-gradient alpine catchment. In our low-gradient catchments, solute concentration was often impacted by discharge, making it difficult to assess the impact of thaw depth on chemistry. Overall, understanding thaw depth dynamics will become increasingly important with climate change, necessitating the development of tools to document and predict thaw depth at a range of scales. Here, we find that stream tracers of thaw at the catchment scale show promise, but it is much more nuanced and complex than preliminary studies indicated.

How to cite: Grose, A., Zarnetske, J., Grewal, A., Rec, A., O'Donnell, J., Shogren, A., Abbott, B., and Bowden, B.: Does stream chemistry reflect thaw depth on a seasonal scale across Alaskan Arctic permafrost catchments?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14348, https://doi.org/10.5194/egusphere-egu25-14348, 2025.

Beavers (Castor canadensis) are rapidly colonizing the North American Arctic, transforming aquatic and riparian tundra ecosystems. Arctic tundra may respond differently than temperate regions to beaver engineering due to the presence of permafrost and the paucity of unfrozen water during winter. Here, we provide a detailed investigation of 11 beaver pond complexes across a climatic gradient in Arctic Alaska, addressing questions about the permafrost setting surrounding ponds, the influence of groundwater inputs on beaver colonization and resulting ponds, and the change in surface water and aquatic overwintering habitat. Using field measurements, in-situ dataloggers, and remote sensing, we evaluate permafrost, water quality, pond ice phenology, and physical characteristics of impoundments, and place our findings in the context of pond age, local climate, permafrost setting, and the presence of perennial groundwater inputs. We show beavers are accelerating the effects of climate change by thawing permafrost adjacent to ponds and increasing liquid water during winter. Beavers often exploited groundwater upwellings in discontinuous permafrost, and summertime water temperatures at groundwater-fed (GW) beaver ponds were roughly 5°C lower than sites lacking perennial groundwater inputs (NGW). Late winter liquid water was present at all but a recently abandoned pond complex, although liquid water below seasonal ice cover was shallow (0–82 cm at GW ponds; 0–15 cm at NGW ponds) and ice was thick (median: 83 cm at GW ponds; 120 cm at NGW ponds). Water was less acidic at GW than NGW sites and had higher specific electrical conductivity and more dissolved oxygen. We estimated 3.2 dams/km of stream at sites on the recently-colonized (last ~10 years) Baldwin Peninsula and 8.0 dams/km on the Seward Peninsula, where beavers have been present longer (~20+ years) and groundwater-surface water connectivity is more common. Our study highlights the importance of climatic and physiographic context, especially permafrost presence and groundwater inputs, in determining the characteristics of the Arctic beaver pond environment. As beavers continue their expansion into tundra regions, these characteristics will describe the future of aquatic and riparian Arctic ecosystems.

How to cite: Tape, K., Glass, T., Jones, B., Rangel, R., and Zavoico, S.: Permafrost ecohydrology of beaver ponds in Arctic Alaska, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7078, https://doi.org/10.5194/egusphere-egu25-7078, 2025.

Quantitative simulation of permafrost dynamics, both under current climatic conditions and future climate change scenarios, presents significant challenges. These include, but are not limited to, long computation times, the construction of accurate surface boundary conditions, and the estimation of transfer properties for soil, organic matter, and vegetation layers that cover (sub-)Arctic regions. The challenges of permafrost simulation are exemplified by the broad range of scenarios for near-surface permafrost evolution under climate change, as indicated by climate models. These range from minimal changes by 2100 under the SSP1-2.6 scenario to complete disappearance as early as 2080 under the SSP5-8.5 scenario (IPCC, 2022). The HiPerBorea project (hiperborea.omp.eu) has developed and applied innovative methodologies to address these challenges. This includes leveraging high-performance computing (Orgogozo et al., 2023; Xavier et al., 2024) and experimental characterizations with X-ray computed tomography (Cazaurang et al., 2023, Cazaurang, 2023). Results will be presented for case studies at two environmental monitoring sites in Siberia: a continuous permafrost area with boreal forest in Central Siberia and a discontinuous permafrost-bearing area with peatlands in Western Siberia. For instance, in the Central Siberia study site, a 40 km² headwater catchment, projected increase of the active layer depth by 2100 under scenario SSP5-8.5 corresponds to a ∼350 km southward shift in current climatic conditions (Xavier et al., 2024). As another example of results, the hydraulic conductivity of the tens of cm thick moss cover of the Western Siberia site has been shown to be higher than previously reported in the literature (Cazaurang et al., 2023). The associated applications and perspectives for further development will also be discussed.

Intergovernmental Panel on Climate Change (IPCC), 2022. Cambridge University Press. https://doi.org/10.1017/9781009157964

Cazaurang S. et al., 2023. Hydrol. Earth Syst. Sci., 27, 431–451, 2023 https://doi.org/10.5194/hess-27-431-2023

Cazaurang S., 2023. PhD thesis of Toulouse INP.

Orgogozo L. et al., 2023. Computer Physics Communications 282 (2023) 108541 https://doi.org/10.1016/j.cpc.2022.108541

Xavier T. et al., 2024. The Cryosphere, 18, 5865–5885, https://doi.org/10.5194/tc-18-5865-2024

How to cite: Laurent, O., Thibault, X., Anatoly, P., Esteban, A.-G., Simon, G., Simon, C., Manuel, M., Michel, Q., Stéphane, A., Liudmila, S., Antonin, M., Emmanuel, M., Sergey, L., Artem, L., and Oleg, P.: Numerical and experimental studies of coupled heat and water transfers in permafrost-bearing continental surfaces: advances of the HiPerBorea project, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6315, https://doi.org/10.5194/egusphere-egu25-6315, 2025.

In the northern periphery, acceleration of hydrological cycle due to global warming include an increase in frequency and intensity of extreme events. Among the consequences of these extreme events in wintertime one can observe an increase of damage to the built environment and natural landscape in the form of fractures. These result from changes in the rain/snow relationship, snowmelt and freeze-thaw cycles. Sometimes these fractures initiate and develop in a manner accompanied by a sudden release of (seismic) energy, commonly known as frost quakes.

Our objective is to study soil freezing, cryosuction phenomena and its relation to occurrence of frost quakes in northern periphery in Finland in the city of Sodankylä. We build a 1D hydrological model that accounts for snow accumulation and melt and heat transfer into to soil and liquid/gas/ice content in subsurface. The hydrological 1D model was calibrated against the measured soil water content and temperature at five different depths in soil during the wintertime 2023/2024. The aim of this study is to understand the ice lens formation, cryosuction process, change in the air and the soil temperature and how these are connected to frost quake occurrence. During the winter 2023/2024 several frost quakes occurred in Sodankylä that are related to rapid change in air temperature, soil temperature and change in cryosuction pressure.

How to cite: Okkonen, J. and Remes, J.: Thermo-hydrological modeling of ground freezing and its relations to occurrence of frost quakes in northern Finland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14966, https://doi.org/10.5194/egusphere-egu25-14966, 2025.

The Arctic is warming two to four times faster than the global average, leading to permafrost thaw and changes in groundwater flow due to alterations in the timing and the depth of the active layer. These changes may lead to previously immobilized contaminants being transported through the active layer; these new pathways for contaminant migration raises concerns, given that there are an estimated 13,000 to 20,000 industrially contaminated sites, many of which remain unremediated. Understanding how the mobilization of contaminants in a high-Arctic settings is crucial to understand to ensure the safety of northern community water resources. The objective of our research is to assess how changing active layer dynamics affects the transport behavior of contaminants in a continuous permafrost hillslope environment via a numerical modeling approach.

For this study, we use SUTRA-solice, a version of the US Geological Survey SUTRA model that incorporates mass transport processes with groundwater flow and energy transport with dynamic freeze-thaw processes. We simulate a 280 m long, two-dimensional transect that terminates in a lake. The site has an unconsolidated overburden of 2 m over crystalline bedrock and contains continuous permafrost. The model results focus on seasonal contaminant migration through the active layer and discharge into the lake via groundwater flux. By untangling the relationship between climate change processes (increased temperature, precipitation, etc.) alongside contaminants migration, we are able to understand how constituent migration through evolving active layers will impact down-slope water sources.

How to cite: Stribling, S., Basijokaite, R., Mohammed, A., Lamontagne-Hallé, P., and McKenzie, J.: Climate Change Impacts on Contaminant Transport and Active Layer Groundwater Dynamics in the High Arctic, Canada, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14360, https://doi.org/10.5194/egusphere-egu25-14360, 2025.