Englacial and subglacial water flow at Skálafellsjökull, Iceland derived from ground penetrating radar,in situGlacsweb probe and borehole water level measurements

Abstract

We reconstruct englacial and subglacial drainage at Skálafellsjökull, Iceland, using ground penetrating radar (GPR) common offset surveys, borehole studies and Glacsweb probe data. We find that englacial water is not stored within the glacier (water content~0-0.3%). Instead, the glacier is mostly impermeable and meltwater is able to pass quickly through the main body of the glacier via crevasses and moulins. Once at the glacier bed, water is stored within a thin (1 m) layer of debris-rich basal ice (2% water content) and the till. The hydraulic potential mapped across the survey area indicates that when water pressures are high (most of the year), water flows parallel to the margin, and emerges 3 km down glacier at an outlet tongue. GPR data indicates that these flow pathways may have formed a series of braided channels. We show that this glacier has a very low water-storage capacity, but an efficient englacial drainage network for transferring water to the glacier bed and, therefore, it has the potential to respond rapidly to changes in melt-water inputs.

Channelized, distributed, and disconnected: subglacial drainage under a valley glacier in the Yukon

“…Observations by Hart et al (2015) using wireless pressure sensors installed across the basal till layer in a glacier in Norway showed that, while a sensor at the ice-till interface shows clear diurnal variations, another one placed a short distance away inside the till layer can show a signal very similar to our disconnected boreholes. This could be a problem affecting some of our sensors, as borehole drilling could eventually penetrate the till.…”

Surface melt‐driven seasonal behaviour (englacial and subglacial) from a soft‐bedded temperate glacier recorded by in situ wireless probes

“…The results from the 2008 and 2011 surveys were reported in Hart et al (2015), and the same techniques are used to analyse the 2012 data. The results from the 2008 and 2011 surveys were reported in Hart et al (2015), and the same techniques are used to analyse the 2012 data.…”

“…We calculate a mean attenuation value (see Hart et al, 2015, for details), and apply this as the best-fit line to the data, as returned power verses depth. These values were plotted as a histogram and three peaks are identified and these were used to quantify bed strength (see figure 6 in Hart et al, 2015). These values were plotted as a histogram and three peaks are identified and these were used to quantify bed strength (see figure 6 in Hart et al, 2015).…”

“…The distance from the fitted line is a measure of relative basal reflectivity for each point (Jacobel et al, 2009(Jacobel et al, , 2010. These values were plotted as a histogram and three peaks are identified and these were used to quantify bed strength (see figure 6 in Hart et al, 2015).…”

Subglacial drainage characterization from eight years of continuous borehole data on a small glacier in the Yukon Territory, Canada

“…Observations by Hart et al (2015) using wireless pressure sensors installed across the basal till layer in a glacier in Norway showed that, while a sensor in the ice-till interface shows clear diurnal variations, another one placed a short distance away…”