Hydrological changes in Bayelva catchment (Western Svalbard-Norway): water discharge quantification and water-driven biogeochemical fluxes

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.