Automated monitoring of subglacial hydrological processes with ground‐penetrating radar (GPR) at high temporal resolution: scope and potential pitfalls

Kulessa, Bernd; Booth, Adam; Hobbs, Andrew; Hubbard, Alun

doi:10.1029/2008gl035855

Cited by 20 publications

(27 citation statements)

References 18 publications

(17 reference statements)

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“…To resolve changes in IRP with depth,

I R P^{*}

was also averaged over 50 m depth intervals (equivalent to

t_{normalf} - t_{normali} = 595

ns in equation ) for each sounding, denoted

{\overset{I R P}{true}}_{n}^{*}

, where

n

represents the upper limit of the depth interval of interest (m). To account for variations in the reflection power of overlying ice, we applied a local correction similar to those applied by Jania et al () and Kulessa et al ():

c {\overset{I R P}{true}}_{n}^{*} = {\overset{I R P}{true}}_{n}^{*} {\overset{I R P}{true}}_{0 - n}^{*},

where

{\overset{I R P}{true}}_{0 - n}^{*}

is the depth‐averaged standardized IRP from 0 to

n

m. By applying the local correction, targets where the overlying IRP is high are adjusted to account for the lower amount of energy transmitted to the target depth, and vice versa. This method has the added benefit of partially accounting for variations in transmitted energy or antenna‐surface coupling.…”

Section: Methodsmentioning

confidence: 99%

“…To resolve changes in IRP with depth, IRP * was also averaged over 50 m depth intervals (equivalent to t f −t i = 595 ns in equation (6)) for each sounding, denoted IRP * n , where n represents the upper limit of the depth interval of interest (m). To account for variations in the reflection power of overlying ice, we applied a local correction similar to those applied by Jania et al (2005) and Kulessa et al (2008):…”

Section: Internal Radar Reflection Power and Englacial Hydrologymentioning

confidence: 99%

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The Role of Englacial Hydrology in the Filling and Drainage of an Ice‐Dammed Lake, Kaskawulsh Glacier, Yukon, Canada

et al. 2020

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Outburst floods from ice‐marginal lakes are poised to become more prevalent in a warming climate. As glaciers thin and tributaries detach, water can be impounded in these unstable lakes at valley confluences. To characterize the role of the little‐studied englacial hydrological system during an outburst flood cycle, we deployed a variety of geophysical and hydrometeorological instruments in and around an ice‐marginal lake dammed by the Kaskawulsh Glacier, Yukon, Canada, to capture its 2017 filling and drainage. The subaerial lake reached a maximum volume of 9.9 ±0.5×106 m 3 on 17 August before draining over the course of ∼19 days. During lake filling, abrupt changes in ice shelf uplift rates are associated with the formation of faults and fractures. These hydromechanical interactions are closely linked to a redistribution of englacial water as evidenced by fluctuations in shallow borehole water pressures, and changes in radar internal reflection power. Water balance calculations reveal that the subaerial, subglacial, and englacial reservoirs respectively store 20 (17–23)%, 40 (25–50)%, and 40 (30–60)% of water in the catchment at peak lake level. The calculated englacial storage volume implies saturated porosities up to 4–10% locally or 2–4% catchment‐wide. The englacial system is therefore both volumetrically important and influenced by the hydromechanical interactions between the lake and glacier. Its spatial extent and storage capacity may play a role in lake drainage initiation, modulation of the flood hydrograph, and lake refilling.

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“…To resolve changes in IRP with depth,

I R P^{*}

was also averaged over 50 m depth intervals (equivalent to

t_{normalf} - t_{normali} = 595

ns in equation ) for each sounding, denoted

{\overset{I R P}{true}}_{n}^{*}

, where

n

c {\overset{I R P}{true}}_{n}^{*} = {\overset{I R P}{true}}_{n}^{*} {\overset{I R P}{true}}_{0 - n}^{*},

where

{\overset{I R P}{true}}_{0 - n}^{*}

is the depth‐averaged standardized IRP from 0 to

n

Section: Methodsmentioning

confidence: 99%

Section: Internal Radar Reflection Power and Englacial Hydrologymentioning

confidence: 99%

The Role of Englacial Hydrology in the Filling and Drainage of an Ice‐Dammed Lake, Kaskawulsh Glacier, Yukon, Canada

et al. 2020

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“…This is evacuated and progressively exhausted through the melt season such that the degree of daily clockwise hysteresis may reduce (Clifford et al, 1995;Hodgkins, 1996;Mao & Carrillo, 2017;Riihimaki, MacGregor, Anderson, Anderson, & Loso, 2005;Stott, Nuttall, & Biggs, 2014). It may also reduce due to the development of more channelized subglacial streams which reduce meltwater access to the bed of the glacier where sediment has accumulated and hence reduces sediment supply (Gimbert, Tsai, Amundson, Bartholomaus, & Walter, 2016;Kulessa, Booth, Hobbs, & Hubbard, 2008;Mair, Nienow, Sharp, Wohlleben, & Willis, 2002;Nienow et al, 1998;Swift, Nienow, Spedding, & Hoey, 2002).…”

Section: Fertilization Of Sediments By Biofilmsmentioning

confidence: 99%

Ecosystem engineers: Biofilms and the ontogeny of glacier floodplain ecosystems

et al. 2019

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The term “ecosystem engineering” emerged in the 1990s and is commonly used to refer to the activities of larger organisms like beavers and trees in rivers and streams. The focus on larger organisms may be motivated by their more visible effects on the environment. However, while it may be intuitive to suggest that the bigger the organism the bigger its potential engineering effects, there may be microscale organisms who through their number rather than their size can act simultaneously to result in significant impacts. This paper considers biofilms as a candidate ecosystem engineer. It is well known that biofilms play an important role in enriching the sediment matrix of nutrients and in stabilizing sediments. Biofilms may be critical in increasing the habitability of the benthic substratum. In this paper, we consider their potential role in the ontogeny of ecosystems in recently deglaciated terrain. We show how by changing sediment stoichiometry, decreasing sediment erodibility, and reducing surface sediment permeability they may promote primary succession on lateral, incised terraces, which are less perturbed compared with the main active floodplain. This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Science of Water > Water and Environmental Change

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“…The quantity and distribution of this stored water is important because water content has a strong influence on ice rheology (Duval, 1977), affecting the contribution (rate and amount) of internal ice deformation to net glacier motion. These effects are difficult to predict because water content often varies spatially (Macheret and Glazovsky, 2000;Murray et al, 2000) and temporally (Jacobel and Raymond, 1984;Macheret and Glazovsky, 2000;Irvine-Fynn et al, 2006;Kulessa et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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

Hart

Rose

Clayton

et al. 2015

Earth Surf Processes Landf

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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.

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Automated monitoring of subglacial hydrological processes with ground‐penetrating radar (GPR) at high temporal resolution: scope and potential pitfalls

Cited by 20 publications

References 18 publications

The Role of Englacial Hydrology in the Filling and Drainage of an Ice‐Dammed Lake, Kaskawulsh Glacier, Yukon, Canada

The Role of Englacial Hydrology in the Filling and Drainage of an Ice‐Dammed Lake, Kaskawulsh Glacier, Yukon, Canada

Ecosystem engineers: Biofilms and the ontogeny of glacier floodplain ecosystems

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

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