Water balance and its intra-annual variability in a permafrost catchment: hydrological interactions between catchment, lake and talik

Abstract

Few hydrological studies have been made in Greenland with focus on permafrost hy-drology rather than on the glacial hydrology associated with the Greenland ice sheet. Understanding permafrost hydrology, and its reflection and propagation of hydrocli-matic change and variability, however, can be a key to understand important climate 5 change effects and feedbacks in arctic landscapes. This paper presents a new extensive and detailed hydrological dataset, with high temporal resolution of main hydrological parameters, for a permafrost catchment with a lake underlain by a talik close to the Greenland ice sheet in the Kangerlussuaq region, western Greenland. The paper describes the hydrological site investigations and data collection, and their synthesis 10 and interpretation to develop a conceptual hydrological model. The catchment and lake water balances and their intra-annual variability, and uncertainty intervals for key water balance components, are quantified. The study incorporates all relevant hydrological processes within the catchment and, specifically, links the surface water system to both supra-permafrost and sub-permafrost groundwater. The dataset enabled water 15 balance quantification with high degree of confidence. The measured hydraulic gradient between the lake and the groundwater in the talik shows this to be a groundwater recharging talik. Surface processes, dominated by evapotranspiration during the active flow period, and by snow dynamics during the frozen winter period, influence the temporal variation of groundwater pressure in the talik. This shows the hydrology in the 20 catchment as being rather independent from external large-scale landscape features, including those of the close-by ice sheet.