How rock glacier hydrology, deformation velocities and ground temperatures interact: Examples from the Swiss Alps

Kenner, Robert; Pruessner, Luisa; Beutel, Jan; Limpach, Philippe; Phillips, Marcia

doi:10.1002/ppp.2023

Cited by 59 publications

(95 citation statements)

References 39 publications

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“…Furthermore, water seems to play a more important role in the active layer of SBE than in COR, as the measured active layer temperatures show a distinct zero curtain. The occurrence of water in the active layer of SBE was also reported by other studies (e.g., Kenner et al, 2019). Water in the active layer can, at least seasonally, reduce the circulation of air and lower the influence of air convection in the active layer.…”

Section: Site Dependencesupporting

confidence: 83%

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Air Convection in the Active Layer of Rock Glaciers

Wicky

Hauck

2020

Front. Earth Sci.

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Coarse blocks are an abundant surface cover in mountainous permafrost landscapes. In this coarse blocky layer, air convection occurs and has a significant influence on the ground thermal regime of the underlying permafrost. Besides heat transfer through conduction, free convection of air takes place seasonally and leads to a pronounced ground cooling. Air convection has been observed and described in many field studies but is often neglected or parametrized in permafrost modeling. In the present study, air convection in the active layer of rock glaciers is explicitly modeled through a heat conduction equation coupled with Darcy's law over a two-dimensional geometry. With a series of numerical experiments, we show its effects on the thermal regime of the underlying permafrost. The ground permeability and the thermal gradient in the active layer are the most important parameters for air convection in the ground. On field sites with a high ground permeability (order of magnitude 10 −6 m 2), convection plays a crucial role and is required to correctly model measured borehole temperatures. The onset of natural convection occurs at critical Rayleigh numbers and is characterized by an increase of the standard deviation of the direction and the vorticity of the airflow field in the active layer. In the numerical solutions, the internal air circulation in the coarse blocky surface layer leads to an efficient ground cooling.

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Section: Site Dependencesupporting

confidence: 83%

“…At SBE less information is available. A previous study reports the presence of water in the active layer (Kenner et al, 2019) and the freezing process is visible in the temperature data of the active layer ( Figure 4A, cf section "Site Dependence"). The presence of water fills the pores and prevents convective circulation of air.…”

Section: Permeabilitymentioning

confidence: 69%

Air Convection in the Active Layer of Rock Glaciers

Wicky

Hauck

2020

Front. Earth Sci.

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“…In some of these cases, the variations in creep velocity followed decadal variations in mean annual air temperatures. All these studies underline the influence of variations in mean annual air or ground temperature on rock glacier speed, through mechanisms such as heat conduction or melt water advection (Ikeda et al, 2008;Kenner et al, 2017;Kenner et al, 2019). Decrease in speed was also shown to coincide with a significant surface lowering, thus hinting to a degradation of ice-rich permafrost (Bodin et al, 2009).…”

Section: Introductionmentioning

confidence: 91%

“…Besides rock glacier distribution, rock glacier creep speed is considered a valuable indicator of environmental, in particular of climatic and ground-thermal conditions. Rock glacier creep speed is expected to increase with ground temperature (Kääb et al, 2007;Arenson et al, 2015;Müller et al, 2016), although it will also be influenced substantially by a number of other factors such as topography (e.g., slope), provision of ice and debris, temporal and vertical variations in ice content, rheology of the frozen debris, thickness, as well as advection or internal production of water (Jansen and Hergarten, 2006;Cicoira et al, 2019;Kenner et al, 2019). The response of rock glacier creep speeds to rising ground temperatures is expected to be especially variable around thawing conditions, i.e.…”

Section: Introductionmentioning

confidence: 99%

Inventory, motion and acceleration of rock glaciers in Ile Alatau and Kungöy Ala-Too, northern Tien Shan, since the 1950s

Kääb

Strozzi

Bolch

et al. 2020

Preprint

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Abstract. Spatio-temporal patterns of rock glacier creep have rarely been studied outside the densely populated European Alps. This study investigates the spatial and temporal variability of rock glacier motion in the Ile Alatau and Kungöy Ala-Too mountain ranges, northern Tien Shan. Over the study region of more than 3000 km2, an inventory of slope movements is constructed using a large number of radar interferograms and high-resolution optical imagery. The inventory includes more than 900 landforms, of which around 550 are interpreted as rock glaciers. Out of the active rock glaciers, 45 are characterised by a rate of motion exceeding 1 m/a. From these fast rock glaciers we select six and study them in more detail (Gorodetzky, Morenny, Archaly, Ordzhonikidze, Karakoram and Kugalan Tash rock glaciers) using offset tracking between airphotos, and historical and modern very high resolution optical satellite data. Most of them show an overall increase of decadal surface velocities from the 1950s onwards with speeds being roughly two to three times higher in recent years compared to the 1950s and 1960s. This development indicates a possible significant increase in sediment and ice fluxes through rock glaciers and implies that – when compared to glacier shrinkage – periglacial sediment transport in the region seems to gain importance relative to glacial sediment transport. Those rock glacier fronts reaching the valley floors show a strongly compressive flow regime, and changes in speeds further upstream affect them only in a damped way. The only rock glacier investigated in detail that does not exhibit an overall increase in speed since the 1950s is Gorodetsky where glacier retreat and dead-ice degradation seem to have decoupled the rock glacier from its supply by glacial sediments and ice.

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“…Velocity variations of rock glaciers are additionally affected by liquid water availability and ground water fluxes (Ikeda et al, 2008) after rain fall and snowmelt indicating increased pore water pressure temporarily enhancing shearing (Cicoira et al, 2019;Kenner et al, 2017;Wirz et al, 2016). Thus, the kinematics of rock glaciers interacts with their hydrology and ground temperatures (Kenner et al, 2019). Interannual vertical variations of the surface topography are studies investigated groundwater flow pathways in rock glaciers (Harrington et al, 2018) and other landforms of mountain watersheds sustaining stream runoff during dry periods (Langston et al, 2011;McClymont et al, 2012;McClymont et al, 85 2010).…”

Section: Introductionmentioning

confidence: 99%

Ice content and interannual water storage changes of an active rock glacier in the dry Andes of Argentina

Halla¹,

Blöthe²,

Baldis³

et al. 2020

Preprint

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Abstract. The quantification of volumetric ice and water contents in active rock glaciers is necessary to estimate their role as water stores and contributors to runoff in dry mountain catchments. In the semi-arid to arid Andes of Argentina, active rock glaciers potentially constitute important water reservoirs due to their widespread distribution. Here however, water storage capacities and their interannual changes have so far escaped quantification in detailed field studies. Volumetric ice and water contents were quantified using a petrophysical four-phase model (4PM) based on complementary electrical resistivities (ERT) and seismic refraction tomographies (SRT) in different positions of Dos Lenguas rock glacier in the Upper Agua Negra basin, Argentina. We derived vertical and horizontal surface changes of the Dos Lenguas rock glacier, for the periods 2016–17 and 2017–18 using drone-derived digital elevation models (DEM). Interannual water storage changes of −36 mm yr−1 and +27 mm yr−1 derived from DEMs of Difference (DoD) for the periods 2016–17 and 2017–18, respectively, indicate that significant amounts of annual precipitation rates can be stored in and released from the active rock glacier. Heterogeneous ice and water contents show ice-rich permafrost and supra-, intra- and sub-permafrost aquifers in the subsurface. Active layer and ice-rich permafrost control traps and pathways of shallow ground water, and thus regulate interannual storage changes and water releases from the active rock glacier in the dry mountain catchment. The ice content of 1.7–2.0 × 109 kg in the active Dos Lenguas rock glacier represents an important long-term ice reservoir, just like other ground ice deposits in the vicinity, if compared to surface ice that covers less than 3 % of the high mountain catchment.

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How rock glacier hydrology, deformation velocities and ground temperatures interact: Examples from the Swiss Alps

Cited by 59 publications

References 39 publications

Air Convection in the Active Layer of Rock Glaciers

Air Convection in the Active Layer of Rock Glaciers

Inventory, motion and acceleration of rock glaciers in Ile Alatau and Kungöy Ala-Too, northern Tien Shan, since the 1950s

Ice content and interannual water storage changes of an active rock glacier in the dry Andes of Argentina

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