Although recent mass loss of the Antarctic ice sheet (AIS) is predominantly driven by ice shelf thinning and increased solid ice discharge, surface processes also directly affect mass changes. Snowfall fluctuations control the variability in surface mass balance (SMB) of the grounded AIS, while meltwater ponding threatens the viability of floating ice shelves. Surface processes are thus essential to quantify present and project future AIS mass loss, but remain poorly represented in climate models running at 25-100 km spatial resolution. Here we present new, daily Antarctic SMB products at 2 km resolution, statistically downscaled from the output of RACMO2.3p2 at 27 km resolution, for the contemporary climate (1979-2021) and a low, moderate and high-end warming scenario until 2100. We show that statistical downscaling to 2 km resolution modestly enhances contemporary SMB (+8%) but strongly increases melt (+50%), notably in the vicinity of the grounding line, in better agreement with both in situ and remote sensing records. The melt increase in the downscaled products persists in the future projections irrespective of the scenario, suggesting a systematic underestimate in low-resolution (regional) climate models.

How to cite: Noël, B., van Wessem, M., Wouters, B., Trusel, L., Lhermitte, S., and van den Broeke, M.: Statistical downscaling increases Antarctic ice sheet surface melt rate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6493, https://doi.org/10.5194/egusphere-egu23-6493, 2023.

Hydrofracture and rapid lake drainage can transport surface meltwater to the bed of the Greenland Ice Sheet, thereby coupling surface mass balance processes and dynamic mass loss. Vertical hydrofracture is widely assumed to occur in the ablation zone, where abundant surface runoff that can fill fractures. However, in Greenland, the runoff line has expanded into the accumulation zone due to the development of ice slabs in the firn. It remains unclear whether surface runoff from these ice slab regions also drains locally to the bed. Recent observations in Northwest Greenland suggest that when meltwater penetrates ice slabs via surface fractures, it leaks off into a relict firn layer and does not initiate unstable vertical hydrofracture that propagates throughout the ice thickness. At the same time, buried supraglacial lakes have been observed to drain to the ice sheet bed this same region. Therefore, to assess the mass balance impact of ice slab expansion, it is important to understand if and when surface-to-bed hydrofracture may occur in these regions.

In “Vulnerability of Firn to Hydrofracture, Part I: Poromechanical Modeling”, we developed an analytic expression for the maximum tensile effective stress within the firn layer beneath a water-filled fracture in an ice slab. Here we apply this model to Greenland’s ice slab regions. We use an ensemble of in situ and remote sensing observations to constrain the physical, mechanical, and hydraulic parameters in our model. We then run a Monte Carlo analysis to constrain the physically-plausible range of maximum tensile effective stress in the firn for two scenarios: a water-filled crevasse in an ice slab or a supraglacial lake over a fractured ice slab. Our results show that the maximum stress in the firn layer is always less than in an equivalent solid ice column, and typically remains compressive, because the imposed load is partially accommodated by a change in pore pressure. An overlying lake further stabilizes the system by increasing the lithostatic stress that acts to close the fracture. Therefore, in Greenland, the relict firn layer can be an important stabilizing factor that suppresses surface-to-bed hydrofracture under ice slabs, despite the abundance of both surface crevassing and meltwater.

How to cite: Culberg, R., Meng, Y., and Lai, C.-Y.: Vulnerability of Firn to Hydrofracture, Part II: Greenland’s Ice Slab Regions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3996, https://doi.org/10.5194/egusphere-egu23-3996, 2023.

Meltwater retention on the surface of ice shelves may lead to hydrofracturing and ultimately their breakup and collapse. Several methods have been used to map surface meltwater on ice shelves from satellite imagery, but a comparison of the methods and a systematic analysis of the results has not been undertaken. Here we bring together two recent inventories of surface meltwater features that use machine learning technologies to map: i) ponds from both Sentinel-2 optical and Sentinel-1 SAR imagery; and ii) both ponds and slush from Landsat 8 optical imagery. We analyse the meltwater products at a bi-monthly (twice a month) timescale over six austral summers between November 2015 and March 2021 for the George VI Ice Shelf, Antarctic Peninsula. We investigate the data sets to reveal the seasonal evolution of surface and shallow subsurface meltwater in terms of the onset, cessation and therefore duration of slush and ponded water, as well as the persistency of slush and ponded water areas from year to year. We find areas where the evolution follows similar patterns from year to year, but also highly anomalous patterns and timings in other years. Finally, a systematic analysis of Sentinel 1 imagery throughout the winter seasons reveals several perennial shallow surface water bodies.

How to cite: Willis, I., Deakin, K., Dell, B., and Dirscherl, M.: Intra- and inter-annual melt water patterns on George VI Ice Shelf, Antarctic Peninsula, from synthetic aperture radar and optical satellite imagery, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9677, https://doi.org/10.5194/egusphere-egu23-9677, 2023.

Hundreds of surface lakes are known to form each summer on north George VI Ice Shelf, Antarctic Peninsula. To investigate surface-meltwater induced ice-shelf flexure and fracture, we obtained Global Navigation Satellite System (GNSS) observations and ground-based timelapse photography over north George VI for three melt seasons from November 2019 to November 2022

In particular, we used these field observations to characterize the flexure and fracture behaviour of a pre-existing doline (i.e. drained lake basin) on north George VI during the record-high melt season of 2019/2020. The GNSS displacement timeseries shows a downward vertical displacement of the doline centre with respect to the doline rim of ~80 cm in response to loading from the development of a central meltwater lake. Viscous flexure modelling indicates that this vertical displacement likely generates flexure stresses of ~> 75 kPa. The GNSS data also show a 10s of days episode of rapid-onset, exponentially decaying horizontal displacement where the horizontal distance from the rim of the doline with respect to its center increases by ~70 cm. We interpret this event as the initiation and/or widening of a single fracture, possibly aided by the availability of surface meltwater (i.e. hydrofracture). Our observations document for the first time the initiation and/or widening of a “ring fracture” on an ice shelf, equivalent to those fractures proposed to be part of the chain reaction lake drainage process involved in the breakup of Larsen B Ice Shelf in 2002.

How to cite: Banwell, A., MacAyeal, D., Willis, I., Stevens, L., and Dell, R.: Observed and modelled surface meltwater-induced flexure and fracture on north George VI Ice Shelf, Antarctica, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9972, https://doi.org/10.5194/egusphere-egu23-9972, 2023.

The large amount of meltwater reaching the base of a glacier at the beginning of the melt season accelerates its ice flow, as meltwater pressurised in cavities acts as bed lubricant. Proceeding in the melt season, if the erosive power of basal water becomes high enough to prevail on the creep-induced closure of such cavities, channels may form. In this regime, water is efficiently drained towards the ice front, basal pressure abates and ice flow decelerates. The temporary speed-up and deceleration throughout the melt season has been observed in many glaciers in Greenland, especially in the southwest. There, more observations are available and the ablation zone extends hundreds of km inland. Yet, there is no evidence that Northeast Greenland follows this hydrology-induced dynamic behaviour. In fact, very few observations of flow variability during the melt season are available for this area, hampering our understanding of impacts of meltwater on the ice dynamics in these remote arctic regions. In this work we run a fully coupled ice-flow-hydrology model (Elmer/Ice coupled to GlaDS) to explore the feedbacks between surface meltwater and ice-flow variations over the whole basin of Northeast Greenland. We address both seasonal and annual timescales by running the coupled model for successive melt seasons (from May 2016 to the end of September 2018). To do so, we make use of daily surface mass balance and runoff data computed by a fully-fledged surface energy balance model (COSIPY) resolving snowpack processes. Our simulations show a seasonal speed-up due to increase in melt water pressure at the base, followed by a decrease in velocities due to the activation of a channelised system beneath the ice sheet. Our results suggest that the Northeast Greenland presents a complex hydrological system that is comparable to other regions of the ice sheet and hint at hydrology-dynamics mechanisms to be a potential controlling factor in the evolution of the area. 

How to cite: Tabone, I., Fürst, J. J., and Mölg, T.: Seasonal and inter annual effects of meltwater runoff on ice dynamics in Northeast Greenland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6497, https://doi.org/10.5194/egusphere-egu23-6497, 2023.

The drainage efficiency of the subglacial water system evolves during the melt season. However, direct measurement of drainage efficiency under 1000-meters thick ice is challenging. We previously demonstrated that surface observations of rapid lake drainage induced uplifts can be used to assess subglacial transmissivity beneath the ice sheet. When a lake drains, the water reaches the interface between the ice and bed and forms a water-filled blister. This water then drains through the subglacial drainage system. In this study, we use mathematical models to examine the behavior of surface uplift relaxation resulting from different types of drainage systems, including a laminar water sheet, a turbulent water sheet, and a turbulent subglacial channel. Combined with surface GPS observations of five lakes, we showed that the model can be used to study the evolution of subglacial drainage efficiency.

How to cite: Lai, C.-Y., Stevens, L., Behn, M., and Das, S.: Relaxation of water-filled blisters via flow through the subglacial drainage system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11012, https://doi.org/10.5194/egusphere-egu23-11012, 2023.

Ice sheets are highly sensitive to melting in their grounding zones, where they transition from grounded ice to floating. Recent models of the interaction between warm salty ocean water and cold fresh subglacial discharge in the grounding zone suggest that warm water can intrude kilometres beneath the ice sheet, with important consequences for ice dynamics.

Here, we couple a model for warm water intrusion to a simple model of melting and, in doing so, capture a previously ignored feedback between geometry and subglacial water flow that occurs as the grounding zone responds to melting. This feedback enhances the potential for warm water to intrude beneath the grounded ice sheet, and therefore makes high melting in grounding zones more likely.

Intriguingly, our results also suggest that increases in ocean temperature can lead to a tipping point being passed, beyond which ocean water intrudes indefinitely beneath the ice sheet by a process of runaway melting, suggesting a candidate mechanism for dramatic changes in grounding-zone behaviour that are not currently included in ice sheet models, and which may enable them to reproduce previous high warm-period sea levels.

How to cite: Hewitt, I. and Bradley, A.: Tipping point behaviour of submarine melting at ice sheet grounding zones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10070, https://doi.org/10.5194/egusphere-egu23-10070, 2023.

The components Antarctica's subglacial hydrology -for instance water sources, sinks, flow paths and catchments- are still poorly constrained.  In this work we assess the subglacial hydrology of the continent at high resolution (500m) using (1) water inputs from frictional melting derived with a higher order ice flow model combined with existing geothermal heat flux products, (2) BedMachine topography, and (3) a water flow routing model taking uncertainties into account.

We present the following modelling results: probabilistic maps of water flow paths and catchments, potential subglacial lake locations, fluxes across the grounding line, and melt or freeze-on rates due to water flow.  We also present locations where the drainage system configuration, such as the catchment size, is sensitive to model inputs and thus where future field investigations would be particularly valuable.

How to cite: Werder, M. A., Goldberg, D., Malczyk, G., Mankoff, K. D., and Wearing, M.: Antarctica's subglacial hydrology, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15919, https://doi.org/10.5194/egusphere-egu23-15919, 2023.

Subglacial processes in Antarctica are difficult to directly observe and are one of the sources of uncertainty when modelling the response of ice sheets to environmental forcing. Subglacial processes pertain to the type of basal sliding or friction law used, where especially the contrast between viscous (linear) and plastic (Coulomb) sliding makes the latter far more responsive to changes at the marine boundary (Ritz et al., 2015; Brondex et al., 2019; Bulthuis et al., 2019; Sun et al., 2020; Kazmierczak et al., 2022).

Besides the type of sliding, physical basal conditions, such as basal temperatures, bed properties (hard or soft), subglacial water flow and drainage, till properties, and mechanics, also directly affect the ice sheet flow (Clarke, 2005, Cuffey and Patterson, 2010, Kazmierczak et al., 2022),  by affecting the effective pressure (Bueler and Brown, 2009, Winkelmann et al., 2011, van der Wel et al., 2013).

In this study, we investigate how variations in effective pressure determines the evolution of the main marine basins of the West Antarctic Ice Sheet (Pine Island and Thwaites glacier) which are currently exhibiting the largest ice mass loss of the Antarctic ice sheet.

For this purpose, we employ different types of subglacial hydrology for soft and hard bed configurations, which we adapt to simulate individual drainage basins of the Antarctic ice sheet at a km-scale resolution, thus allowing for proper migration of the grounding line (e.g., Pattyn et al., 2013). These hydrological representations are included in a generalized basal sliding law (Zoet et al., 2020), implemented in the the f.ETISh/Kori model (Pattyn, 2017; Sun et al., 2020). Results are compared to results from a pan-Antarctic ice sheet model (Kazmierczak et al., 2022) and demonstrate the importance of detailed bed topography influencing the subglacial conditions upstream of the grounding line.

How to cite: Kazmierczak, E. and Pattyn, F.: Sensitivity of Pine Island and Thwaites drainage basins to subglacial hydrology, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12684, https://doi.org/10.5194/egusphere-egu23-12684, 2023.

As temperatures continues to increase, a larger amount of snow and ice is melting at the surface of ice sheets and glaciers. It is now clear that this increase in meltwater availability has a direct impact on ice dynamics on a seasonal timescale, and there are strong presumption that this is also the case on longer timescales. The recent evolution of subglacial hydrology models now allows them to be directly coupled to ice dynamics model to perform long term simulation of this systems and provide the link between ice dynamics and the evolution of climate. There is however still a large number of open questions to answer in order to provide long term realistic simulations of this coupled system. One of those questions is the impact of the recharge location an intensity of the subglacial hydrological system on ice dynamics, or whether the injection of water in the system needs to pass through Moulins or can be approximated as a uniform source. The impact of the recharge strategy on subglacial hydrology model alone has yielded contrasted results with a potential impact on short timescale but a limited influence once integrated over a full season. Here we want to investigate the direct effect of this recharge scenarios on the ice dynamics itself.

We apply the Ice-sheet and Sea-level System Model (ISSM) to a synthetic glacier with a geometry similar to a Greenland ice sheet land terminating glacier. Using a range of moulin density (or uniform input) for the recharge of the subglacial hydrology model we observe the response of the ice dynamics itself both on short and longer timescales. Those simulations provide an insight into the importance of recharge location and intensity of the subglacial drainage system directly on the ice dynamics, and so provide a baseline for the choice of recharge style for more realistic simulations.

How to cite: de Fleurian, B.: Impact of subglacial hydrology recharge location and intensity on ice dynamics., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11493, https://doi.org/10.5194/egusphere-egu23-11493, 2023.

Subglacial hydrology is a key component in ice sheet dynamics. The presence of subglacial water at the ice-bed interface can significantly reduce basal friction and facilitate rapid ice flow, which could lead to the formation of surges and ice streams. The action of the subglacial network on ice flow is simulated by a range of numerical models. Validating these models is essential to ensure that the important physical processes are included, and that the numerical methods provide accurate solutions. In addition to field measurements, which are challenging to obtain at the ice-bed interface, a common validation technique includes inter-comparison with other numerical models. Even though such a technique is beneficial, it does not provide an equivalent validation as exact solutions. Here we present analytical and semi-analytical solutions for confined and unconfined flows in porous layers to validate subglacial hydrology models, which are based on an effective porous medium (EPM) approach. We then apply them to validate the confined-unconfined aquifer scheme (CUAS) model. We find that the numerical results are consistent with the analytical solutions, which provides more confidence that CUAS accurately solves the hydrology equations. Because of their generality, our solutions are readily applicable to other subglacial hydrology models that are based on an EPM approach. We anticipate that a validated hydrology model with our solutions can achieve more credible results in subglacial network simulations.

How to cite: Schmiedel, J. and Sayag, R.: Validation of a subglacial hydrology model with analytical and semi-analytical solutions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4220, https://doi.org/10.5194/egusphere-egu23-4220, 2023.

The ice-ocean interface of Greenlandic outlet glaciers is the main source of uncertainty in the sea level contribution estimates from the Greenland ice sheet in the coming century. Subglacial discharge of surface meltwater is a currently understudied process that connects atmospheric forcing to the marine terminus. At the terminus, subglacial discharge drives buoyant plumes that enhance melt of the glacier. Surface meltwater from the ice sheet is often assumed to be directly and instantaneously transported to the gounding line as subglacial discharge. However, the subglacial drainage network evolves as a response to changes in surface meltwater volume, thus moderating and distributing the discharge along the grounding line. The early-season and late-season networks are likely to have different transport properties, leading to different properties of the buoyant subglacial discharge plume, and the accompanying melt rate.

We model the subglacial hydrologic network of Sermeq Kujalleq (Jakobshavn Isbræ) glacier in West Greenland with GlaDS in ISSM. We characterize the evolution of subglacial discharge into the fjord throughout the runoff season, and compare different runoff years. Furthermore, we use the MITgcm ocean model of Ilulissat Icefjord to characterize the impact of seasonality of the subglacial discharge to fjord properties, circulation and submarine melt of the glacier front.

How to cite: Kajanto, K., de Fleurian, B., Seroussi, H., Straneo, F., and Nisancioglu, K.: Subglacial discharge as a driver of fjord circulation in Ilulissat Icefjord, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6444, https://doi.org/10.5194/egusphere-egu23-6444, 2023.

Increasingly more significant portions of the Greenland ice sheet are undergoing seasonal melting-refreeze cycles due to climate warming. The process begins with the arrival of warm temperatures and increased solar radiation in the spring and summer seasons generating meltwater on the ice sheet’s surface. Meltwater percolates to deeper ice layers, either refreezing within the firn, creating longer-term meltwater pockets (firn aquifers), or generating peripheral runoff. Depending on the location and climate, the refreeze duration, the depth of infiltration, and meltwater persistence are temporally and spatially complex. Multi-frequency passive microwave measurements in the 1.4 GHz to 36.5 GHz range can distinguish seasonal meltwater between the immediate surface and the deeper firn layers, as demonstrated at experiment sites on the Greenland ice sheet. Here we explored the multi-frequency melt response at the pan-Greenland scale. We employed 1.4 GHz brightness temperature (TB) measurements from the NASA Soil Moisture Active Passive (SMAP) satellite and 6.9, 10.7, 18.9, and 36.5 GHz TB measurements from the JAXA Global Change Observation Mission-Water Shizuku (GCOM-W) satellite. The results show that the frequency-dependent response was consistent across the ice sheet. The multi-frequency melt indications match with lasting seasonal subsurface meltwater with delayed refreezing compared to the surface. These results suggest persistent seasonal subsurface meltwater occurrences that are spatially and temporally significant but concealed from the high-frequency observations. Similar to the surface melt with significant interannual variations, the results show that the subsurface meltwater cycle exhibits substantial spatial and temporal variations from year to year.

How to cite: Colliander, A., Mousavi, M., Kimball, J., Miller, J., and Burgin, M.: Significant Temporal and Spatial Differences in Greenland Ice Sheet Surface and Subsurface Meltwater Persistence Revealed by Multi-Frequency Radiometry, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3647, https://doi.org/10.5194/egusphere-egu23-3647, 2023.

                  David Glacier is a significant East Antarctic outlet glacier through the Transantarctic Mountains and into the western Ross Sea. The six active subglacial lakes (D1~D6) were identified in the David Glacier catchment based on NASA’s Ice, Cloud, and land Elevation Satellite (ICESat) laser altimeter dataset for 4.5 years (2003-2008). Since 2016, Korea Polar Research Institute (KOPRI) has been preparing the hot-water drilling project in the David Glacier, starting with the geophysical surveys. KOPRI’s geophysical research team confirmed the change rate of the surface elevation of the David glaciers based on the analysis of the Double-Differential Interferometric synthetic aperture radar (DDinSAR) from satellite (Sentinel-1A) images for July to August 2015 and March 2017, then selected the D2 subglacial lake as the target for the potential hot-water drilling project. KOPRI’s Antarctic traverse team developed ground routes for logistics from the JBS to the D2 lake site in the 2017-18 season. In the 2018-19 season, a radar survey was conducted on the D2 site, and the lake's global structures and scale were confirmed. Then, in the 2021-2022 season, a multi-channel seismic survey was conducted on the D2 site to image the detailed subglacial structures of the lake. The final goal of this seismic survey is to get information on the optimal site selection for the hot-water-drilling location for subglacial sampling.  The seismic survey was performed for about two months on the ice. Dynamite is used to generating the seismic source; 1.6 kg of dynamites were used per the charging hole. The charging depth is 25 m. 90 m and 180 m shot intervals were used for 8- and 4-fold data acquisition. Four sets of the Geometric Geode and a 96-channel GEOROD system were employed to record the seismic signal from the ice. The group spacing of the receiver (GEOROD) is 15 m. The seismic data were recorded for 4 seconds with two milliseconds sampling rates. The total length of the acquired seismic data is 17.2 km, consisting of 4 survey lines: two south-to-north and two east-to-west lines. The maximum and minimum fold numbers are 8 and 4, respectively. We got high-quality seismic migrated images containing actual structural and geophysical information about the subglacial lake through seismic data processing with advanced denoise and de-ghosting algorithms. We confirmed the thickness of the ice, which can estimate by the depth of the reversed-polarity reflections on the boundaries between the ice and lake water from the migrated seismic sections for each survey line for D2 lake. Also, the 200 m lake water depth, structures, and geophysical characteristics of the subglacial lake were confirmed, and then, we found the optimal hot-water drilling location for the subglacial lake D2 in the David Glacier, Antarctica.

How to cite: Kang, S.-G., Ju, H. T., Choi, Y., Kwak, H., Lee, J., Kim, Y., Hong, J. K., and Lee, J. I.: Imaging the structures of a subglacial lake D2 in the Antarctic David Glacier catchment from the multi-channel reflection seismic records, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4630, https://doi.org/10.5194/egusphere-egu23-4630, 2023.

How to cite: Horgan, H., Dunbar, G., Hulbe, C., Schmidt, B., Stevens, C., Stewart, C., and Werder, M. and the KIS2 Science Team: Subglacial drainage across Kamb Ice Stream’s Grounding Zone, West Antarctica., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1820, https://doi.org/10.5194/egusphere-egu23-1820, 2023.

Radar images imply subglacial features, including distinct reflections from ice bottom. Different from bedrock interfaces, subglacial lakes generally display smooth and continuous highlights as a special type of ice bottom reflectors in radar images. In this study, we construct a dataset of ice bottom reflectors based on CReSIS radar sounder dataset. A deep learning method is applied to downsample and convert peak ice bottom reflectors to latent space. Unsupervised clustering later separates different types of subglacial reflectors. One reflector type with a sharp shape and high reflect power reveals smooth and continuous distributions in the radar images. The spatial distribution of this reflector type also matches the known subglacial lake distribution. We further applied this workflow to indicate candidate groups of subglacial reflectors similar to the conventional lakes. Results show more lakes are marked in the same radar sounder dataset. This method can automatically indicate subglacial lakes in radar images with high efficiency. The other types of subglacial reflectors can also provide potential references for subglacial studies.

How to cite: Dong, S. and Fu, L.: Deep Clustering in Subglacial Reflections Reveals New Insight into Subglacial Lakes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16804, https://doi.org/10.5194/egusphere-egu23-16804, 2023.

Surface water and groundwater are changing rapidly because of significant climate warming in the Arctic region [1,2]. Arctic amplification has intensified the melting of snow cover and glaciers, as well as widespread permafrost degradation, leading to a prominently increase of the annual discharge of some Arctic rivers [3,4]. This results in dramatic impacts on the surface water transition and freshwater circulation that, in turn, can cause localized permafrost thaw [5], allowing greater connection between deep groundwater and surface water pathways. Groundwater is a crucial component of the hydrological cycle, affecting ecosystems and human communities in Arctic regions.

In high-latitude regions, evaluating groundwater flux and storage and river discharge is challenging due to a lack of trusted and publicly available hydrogeological data. Changes in river flows and groundwater discharge will alter fluxes of freshwater and terrigenous material (e.g., sediment, nutrients, and carbon), with implications for biodiversity in both freshwater and marine ecosystems. The rapid glacier melting affects weathering processes, resulting in the mobilization-transport of pollutants, microorganisms stored for a long time, and turbid meltwaters. Consequently, more timely and accurate evaluation of surface and groundwater is urgently required.

Thanks to its geographical characteristics, the retreating glaciers, the research stations and infrastructures, and the studies carried out in the past and present, the Bayelva catchment near Ny-Ålesund (Western Svalbard-Norway) is an ideal site for surveys aimed at increasing knowledge on hydrology dynamics and associated effects, in the continuum from glaciers to the fjord.

In this framework, within the ICEtoFLUX project (MUR/PRA2021 project-0027) field campaigns were conducted in the spring and summer of 2022 in the Bayelva River catchment, from its glaciers and periglacial/proglacial systems up to the Kongsfjorden sector significantly affected by the river.  The activities were aimed at quantifying hydrologic processes and related transport of pollutants and microbial biomass and activities. Suprapermafrost groundwater was monitored by four piezometers installed along a hillslope to investigate how subsurface and surface waters interact during active layer development.

Water samples were repeatedly collected for analysing physical-chemical-isotopic-biological parameters. Main rain events and monthly total precipitation were sampled for stable isotopes.

The first results suggest that, in general, electrical conductivity and total suspended solids increase from the glacier to the Bayelva monitoring station, which is located less than 1 km far from the coast. Seasonal evolution of physical-chemical features was also observed. Results from piezometers indicate that the underground flow is spatially and temporally heterogeneous, both quantitatively and from a physical-chemical-isotopic-biological point of view. A general increase of electrical conductivity over the melt season was registered for groundwater and streamwater. First evidence on organic pollutants and microbe transport are also discussed.

[1] Fichot, C.G. et al. 2013. Sci. Rep., 3, 1053.

[2] Morison, J. et al. 2012. Nature, 481, 66–70.

[3] McClelland, J.W. et al. 2006. Geophys. Res. Lett., 33, L06715.

[4] Wang, P. et al. 2021. Res. Lett., 16, 034046.

[5] Zheng, L. et al. 2019. J. Geophys. Res. Earth Surf., 124, 2324–2344.

How to cite: Baneschi, I., Doveri, M., D'Amico, M., Franceschi, L., Lelli, M., Lo Giudice, A., Maimone, G., Menichini, M., Norelli, F., Patrolecco, L., Pescatore, T., Rappazzo, C. A., Rauseo, J., Spataro, F., Caruso, G., Trifirò, S., Azzaro, M., and Vecchiato, M.: Hydrological changes in Bayelva catchment (Western Svalbard-Norway): water discharge quantification and water-driven biogeochemical fluxes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15825, https://doi.org/10.5194/egusphere-egu23-15825, 2023.

The motion of glaciers with a temperate base is highly variable in time and space, mainly as a result of glacier basal sliding being strongly modulated by subglacial hydrology. Although transient friction laws have recently been established in order to predict short-term sliding velocity changes in response to water input changes, yet little observations enable fully constraining these laws. Here we investigate short-term changes in glacier dynamics induced by transient rainwater input on the Glacier d’Argentière (French Alps) using up to 13 permanent GPS stations. We observe strong surface acceleration events materialized by maximum downglacier velocities on the order of 2 to 3 times background velocities and associated with significant glacier surface uplift of 0.03 m to 0.1 m. We demonstrate that uplift strikingly coincides with water discharge. In contrast, horizontal speed-up occurs over a timescale shorter than discharge and uplift changes, with a maximum occurring concomitantly with maximum water pressure but prior to maximum discharge or uplift. Our findings suggest that transient acceleration and uplift of the glacier are not necessarily modulated by the same mechanism. We also observe that the horizontal speed-ups propagate downglacier at migrating speeds of 0.04 m s-1 to 0.13 m s-1, suggesting an underlying migration of subglacial water flows through the inefficient, distributed system. We demonstrate that the temporal relationship between water discharge, water pressure, and three-dimensional glacier motions are complex and cannot be directly interpreted by changes in the subglacial water pressure through cavity formation and water storage. 

How to cite: Togaibekov, A., Walpersdorf, A., and Gimbert, F.: Rain-induced transient variations in glacier dynamics characterized by a continuous and dense GPS network at the Glacier d’Argentière, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-269, https://doi.org/10.5194/egusphere-egu23-269, 2023.