Rainfall as primary driver of discharge and solute export from rock glaciers: The Col d'Olen Rock Glacier in the NW Italian Alps

High-elevation catchments are rapidly changing as glaciers retreat and permafrost thawing intensifies. Consequently, alpine stream hydrochemistry is shifting but the interaction with complex hydrological and geological settings often confounds the effect of the climatic signal. To evaluate the effect of different glacier coverage and rock glacier presence, our study involves a multi-parameter approach of different tracers in two high-elevation catchments. Both catchments (Schnals and Martell; Eastern Italian Alps) share a comparable metamorphic geology but contrast in their glacier cover (4% and 22%, respectively) and abundance of active rock glaciers (numerous in the Schnals catchment).Based on these different settings, we hypothesized that i) the glacier melt contribution at the daily and monthly scale in Martell is larger than in Schnals, ii) metamorphic catchments share similar hydrochemical patterns along the river network, and iii) rock glacier meltwaters affect more strongly the hydrochemistry of the main stream in Schnals than in Martell, given the higher abundance of active rock glaciers in the former catchment.From June 2019 to October 2020, we carried out a monthly sampling of stream water along the main river, major tributaries, springs and a rock glacier. Snowmelt and ice melt (only at Martell) were occasionally sampled as well. Rain was collected on a monthly basis. Electrical conductivity of water samples was measured on-site while stable water isotopes and concentrations of major, minor, and trace elements were measured in the laboratory.Our results indicate that the isotopic composition of streams and tributaries in Martell mainly originated from snowmelt and ice melt, with a minor contribution from groundwater. In contrast, the contribution of precipitation, shallow groundwater, and rock glaciers was larger in the Schnals catchment. The two catchments showed distinct hydrochemical patterns, based on their different elemental concentrations. Mostly during the glacier ablation period and autumn, alkali elements dominated Schnals hydrochemistry, whereas arsenic and strontium characterized the stream hydrochemistry of Martell. Concentrations of metals and metalloids had a sharp increase during autumn, when thawing permafrost and the subglacial drainage was highest, thus affecting the hydrochemistry of the entire river network. As thawing permafrost increasingly influences the quality of freshwaters in deglaciating catchments, efforts must be dedicated to the long-term monitoring of alpine river networks, given the potential implications for human health and ecosystem quality.

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A complementary kinematic approach to inventory rock glaciers applied to case studies of the Swiss and Italian Alps

10.5194/egusphere-egu21-14661 ◽

2021 ◽

Author(s):

Aldo Bertone ◽

Chloé Barboux ◽

Francesco Brardinoni ◽

Reynald Delaloye ◽

Volkmar Mair ◽

...

Keyword(s):

Swiss Alps ◽

Research Network ◽

Italian Alps ◽

The South ◽

Rock Glacier ◽

Climatic Forcing ◽

Mountain Permafrost ◽

Rock Glaciers ◽

Kinematic Information ◽

Velocity Class

Rock glaciers are the best visual expression of creeping mountain permafrost. Their dynamics, which largely depend on climatic forcing, provide information about the mountain permafrost and may locally pose risk to infrastructures.The International Permafrost Association (IPA) Action Group on Rock glacier inventories and kinematics, launched in 2018, fosters the activities of a research network focused on the definition of standardized guidelines for inventorying rock glaciers, including information on rock-glacier displacement rate. The ESA Permafrost_CCI project further sustains this initiative, and proposes a standardized method to implement kinematics-based rock glacier inventories.The proposed method exploits interferometric data from spaceborne Synthetic Aperture Radar (InSAR) to derive the kinematic information of existing or newly-compiled rock glacier inventories. In particular, areas identified as slope movements within rock glacier polygons are delineated on interferograms as &#8220;moving areas&#8221;, and are assigned a velocity class. Subsequently, a specific kinematic class is assigned to each rock glacier unit according to the velocity class and extension of the relevant moving areas.This method is applied on two regions: the Western part of the Swiss Alps and the South-Western part of the South Tyrol (Italian Alps). Both are located at the same latitude, with rock glaciers in the Swiss part lying at slightly higher altitudes, and experiencing higher mean annual precipitation. Rock glacier polygons were drawn from existing inventories, the kinematic information was extracted exploiting InSAR data acquired between 2018 and 2019 from the Sentinel-1 constellation.In the Swiss and Italian parts, we inventoried 660 and 783 moving areas (1443 in total). Collectively, it was possible to assign a kinematic attribute to 913 rock glaciers, providing a more objective and quantitative activity classification (compared to the qualitative active, inactive, and relict categories). In the Swiss part, 14% of the rock glaciers are moving in the magnitude order of a meter/year or faster, 43% in the magnitude order of one to several dm/yr, 36% from one to several cm/yr, the others are with unreliable movements (7%). In the Italian part, these percentages are 1% (meter/year or faster), 42% (one to several dm/yr), 39% (one to several cm/yr) and 18% (no reliable), respectively. Preliminary analyses on the Italian part are conducted on 467 additional rock glaciers recognized as geomorphologically relict: 68% are not moving or not moving fast enough to be detected, 9% have sectors moving up to several cm/yr, and the remaining 23% of relict rock glaciers have no reliable information on movement.Preliminary results show how this approach allows to provide complementary kinematic information to the geomorphological approach, improving the knowledge on the activity status in a given time and in a given region. Since several studies have reported trends towards displacement acceleration, applying this approach over long periods will allow assessing the response of a wide selection of landforms to (warmer) climatic forcing. Furthermore, this approach is a very useful tool to help select representative rock glaciers of a region, on which to apply more accurate monitoring approaches.

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Rock glacier sediment, kinematics and geomorphometry: a study case from the Eastern Italian Alps

10.5194/egusphere-egu21-9653 ◽

2021 ◽

Author(s):

Federica Minotti ◽

Christian Kofler ◽

Bernhard Gems ◽

Volkmar Mair ◽

Francesco Comiti

Keyword(s):

High Mountain ◽

Ice Melting ◽

Italian Alps ◽

Rock Glacier ◽

Tauern Window ◽

Transport Distance ◽

Glacier System ◽

Mountain Environments ◽

Rock Glaciers ◽

Unconsolidated Rock

Rock glaciers are important geomorphological structures of high mountain environments and fundamental indicators for permafrost. They consist of unconsolidated rock debris &#8211; generally derived from talus or till - held together by ice, moving slowly downslope due to the gravitation in combination with uncountable freeze-thaw-cycles in the active layer. The downslope movement of rock glaciers leads to lobate structures with depressed areas as well as ridges where the sediments tend to accumulate, creating a typical surface morphology defined as "ridges and furrows". This study focuses on the analysis of one rock glacier system located in the Pfitsch/Vizze valley (South Tyrol), in the Eastern Italian Alps.&#160; The debris in this area comprises exclusively the granitic Central Gneiss of the Tauern window. Rock glacier sediment derives from talus, consisting essentially of more or less foliated to planar angular material, which was essentially formed by frost weathering. The size and shape of sediments present at the surface of the rock glacier system were analyzed in correlation with displacement and geomorphometry, with the hypothesis that sediments shape and size at different sites across the rock glacier might relate to its past and present dynamics. The displacement analyses were carried out to quantify rock glaciers movements during the last 20 years, and the geomorphometrical characteristics were investigated to identify specific geometrical attributes that may be linked to internal ice changes. Clasts analysis showed how rock glacier sediments are very heterogeneous, with dimensions being mainly determined by transport distance, and sphericity and roundness by lithology. A role of sediments characteristics on&#160;displacement rate&#160;did not turn out evident. Convexities and concavities observed on the study site are apparently created respectively by the accumulation of sediments and the collapse of the structure due to the internal ice melting. Indeed, the recent, marked increase in air temperature observed in the last decades in the Alps has likely caused an accelerated ice melting in the less protected &#8211; in terms of solar radiation &#8211; rock glaciers, as is the case for our study area. Sediments here are no longer bound by ice and have become rather unstable. Therefore, the monitoring of rock glaciers is fundamental to anticipate future changes in the type and magnitude of natural hazards originating at high elevations, as thicker layers of sediments are becoming increasingly unstable.

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Physical and biological features of an active rock glacier in the Italian Alps

The Holocene ◽

10.1177/0959683614544050 ◽

2014 ◽

Vol 24 (11) ◽

pp. 1624-1631 ◽

Cited By ~ 10

Author(s):

Mauro Gobbi ◽

Francesco Ballarin ◽

Chiara Compostella ◽

Valeria Lencioni ◽

Roberto Seppi ◽

...

Keyword(s):

Grain Size ◽

Plant Distribution ◽

Coarse Grained ◽

Italian Alps ◽

Rock Glacier ◽

Biological Features ◽

Rock Glaciers ◽

Specific Species ◽

Physical Features ◽

Unique Species

We report on the key physical features of an active rock glacier that influence the distribution of plants and arthropods. We also perform a comparison with neighboring scree slope and alpine grassland to test whether the environmental features of the rock glacier drive the presence of specific species assemblages. Compared with scree slope and grassland, the studied rock glacier provides particular physical features that determine the presence of unique species. Plant distribution is mainly driven by grain size. Arthropod distribution is linked to grain size, with cold-adapted species found on areas with coarse-grained deep debris, which also shows a distinctive temperature regime with very low values throughout the year. On the basis of these findings, we advance the hypothesis that rock glaciers provide specific ecological conditions creating potential refugia for cold-demanding species during warm climatic periods.

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Changes of rock glacier vegetation in 25 years of climate warming in the Italian Alps

CATENA ◽

10.1016/j.catena.2021.105562 ◽

2021 ◽

Vol 206 ◽

pp. 105562

Author(s):

Nicoletta Cannone ◽

Silvia Piccinelli

Keyword(s):

Climate Warming ◽

Italian Alps ◽

Rock Glacier

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Observations on a Debris-Covered Polar Glacier “Whisky Glacier”, James Ross Island, Antarctic Peninsula, Antarctica

Journal of Glaciology ◽

10.1017/s002214300000887x ◽

1987 ◽

Vol 33 (115) ◽

pp. 300-310 ◽

Cited By ~ 25

Author(s):

T.J.H. Chinn ◽

A. Dillon

Keyword(s):

Antarctic Peninsula ◽

Rock Glacier ◽

Freezing Front ◽

Extensive Area ◽

Free Zone ◽

Rock Glaciers ◽

James Ross Island ◽

Polythermal Glacier ◽

Powerful Mechanism

Abstract“Whisky Glacier” on James Ross Island, Antarctic Peninsula, comprises anévéand clean ice trunk surrounded by an extensive area of debris-covered ice resembling a rock glacier. The debris-free trunk of the glacier abuts abruptly against the broad, totally debris-covered tongue at a number of concentric zones where debris-laden beds crop out at the surface in a manner similar to the “inner moraine” formations of many polar glaciers.Ice structures and foliation suggest that “Whisky Glacier” is a polythermal glacier which is wet-based under the debris-free zone, and dry-based under the debris-covered zone. It is surmised that the glacier sole crosses the freezing front close to where the basal debris beds are upwarped towards the surface. Here, basal water is confined, and freezes to the under side of the glacier in thick beds of regelation ice which are uplifted to the surface along with the debris-laden beds. Ablation losses effectively cease beneath the blanket of debris covering the tongue.The transition from wet-based to dry-based conditions at the glacier sole is a powerful mechanism for entraining debris into a glacier and, in the case of “Whisky Glacier”, for lifting debris to the surface. It is suggested that this may be a mechanism for forming some polar rock glaciers.

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Schmidt-hammer exposure-age dating (SHD) of rock glaciers in the Schöderkogel-Eisenhut area, Schladminger Tauern Range, Austria

The Holocene ◽

10.1177/0959683611430410 ◽

2011 ◽

Vol 22 (7) ◽

pp. 761-771 ◽

Cited By ~ 19

Author(s):

Matthias Rode ◽

Andreas Kellerer-Pirklbauer

Keyword(s):

Root Zone ◽

Age Dating ◽

Surface Velocity ◽

Schmidt Hammer ◽

Rock Glacier ◽

Relative Age ◽

Exposure Age ◽

Rock Glaciers ◽

Glacier Length ◽

Eastern Austria

Schmidt-hammer rebound values ( R-values) enable relative-age dating of landforms, with R-values relating to degree of weathering and therefore length of exposure. This method – recently termed as Schmidt-hammer exposure-age dating (SHD) – was applied to date five rock glaciers (size range, 0.01–0.12 km2) and one recent rockfall deposit at the study area Schöderkogel-Eisenhut, in the Schladminger Tauern Range (14°03′E, 47°15′N), Austria. The rock glaciers consist of gneiss or high metamorphic series of mica-schist that are comparable in their R-values. Four of them are relict (permafrost absent) and one is intact (containing patches of permafrost). On each of the five rock glaciers, SHD was carried out at 4–6 sites (50 measurements per site) along a longitudinal transect from the frontal ridge to the root zone. Results at all five rock glaciers are generally consistent with each other sharing statistically significant R-values along transects. The range between the highest and the lowest mean R-value at each of the five rock glaciers is 9.9–5.2. Using rock glacier length and surface velocity data from nearby sites, the rock glacier development must have lasted for several thousand years. Furthermore, by using SHD results from rock glaciers of known age from other sites in the region with comparable geology, approximate surface ages of 6.7–11.4 ka were estimated. This indicates long formation periods for all five rock glaciers. Our results suggest that many of the 1300 relict rock glaciers in central and eastern Austria were formed over a long period during the Lateglacial and Holocene period.

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Photo-Interpretation of two Types of Rock Glacier in the Colorado Front Range, U.S.A.

Journal of Glaciology ◽

10.3189/s0022143000018918 ◽

1965 ◽

Vol 5 (42) ◽

pp. 849-856 ◽

Cited By ~ 2

Author(s):

Samuel I. Outcalt ◽

James B. Benedict

Keyword(s):

Wall Rock ◽

Colorado Front Range ◽

Front Range ◽

Rock Glacier ◽

Floor Rock ◽

Glacial Ice ◽

Photo Interpretation ◽

Two Generations ◽

Rock Glaciers ◽

Small Valley

AbstractTwo types of rock glacier occur in the Colorado Front Range. Rock glaciers on the floors of modern cirques closely resemble the tongues of small valley glaciers. Because they contain cores of banded glacial ice and grade up-valley into lateral moraines, rock glaciers of this type are believed to represent the debris-covered tongues of former glaciers. Most consist of two or more superimposed lobes, bounded by longitudinal furrows, and resulting from independent ice advances. Despite their compound nature, the complexes now appear to be moving down-slope as single units. Two generations of “cirque-floor” rock glaciers, both tentatively dated as being of post-Pleistocene age, occur in the Front Range.Rock glaciers of an entirely different character occur beneath steep valley walls, where they are supplied with debris by avalanche couloirs. Interstitial ice, responsible for the movement of “valley-wall” rock glaciers, probably results from the metamorphism of snow buried beneath rock-fall debris or supplied by winter avalanching.

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Short-term velocity variations at three rock glaciers and their relationship with meteorological conditions

Earth Surface Dynamics ◽

10.5194/esurf-4-103-2016 ◽

2016 ◽

Vol 4 (1) ◽

pp. 103-123 ◽

Cited By ~ 35

Author(s):

V. Wirz ◽

S. Gruber ◽

R. S. Purves ◽

J. Beutel ◽

I. Gärtner-Roer ◽

...

Keyword(s):

Pore Water Pressure ◽

Water Pressure ◽

Ground Surface ◽

Climatic Conditions ◽

Water Infiltration ◽

High Temporal Resolution ◽

Rock Glacier ◽

Short Term ◽

Rock Glaciers ◽

Velocity Variations

Abstract. In recent years, strong variations in the speed of rock glaciers have been detected, raising questions about their stability under changing climatic conditions. In this study, we present continuous time series of surface velocities over 3 years of six GPS stations located on three rock glaciers in Switzerland. Intra-annual velocity variations are analysed in relation to local meteorological factors, such as precipitation, snow(melt), and air and ground surface temperatures. The main focus of this study lies on the abrupt velocity peaks, which have been detected at two steep and fast-moving rock glacier tongues ( ≥  5 m a−1), and relationships to external meteorological forcing are statistically tested.The continuous measurements with high temporal resolution allowed us to detect short-term velocity peaks, which occur outside cold winter conditions, at these two rock glacier tongues. Our measurements further revealed that all rock glaciers experience clear intra-annual variations in movement in which the timing and the amplitude is reasonably similar in individual years. The seasonal decrease in velocity was typically smooth, starting 1–3 months after the seasonal decrease in temperatures, and was stronger in years with colder temperatures in mid winter. Seasonal acceleration was mostly abrupt and rapid compared to the winter deceleration, always starting during the zero curtain period. We found a statistically significant relationship between the occurrence of short-term velocity peaks and water input from heavy precipitation or snowmelt, while no velocity peak could be attributed solely to high temperatures. The findings of this study further suggest that, in addition to the short-term velocity peaks, the seasonal acceleration is also influenced by water infiltration, causing thermal advection and an increase in pore water pressure. In contrast, the amount of deceleration in winter seems to be mainly controlled by winter temperatures.

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

10.5194/tc-2020-29 ◽

2020 ◽

Cited By ~ 3

Author(s):

Christian Halla ◽

Jan Henrik Blöthe ◽

Carla Tapia Baldis ◽

Dario Trombotto ◽

Christin Hilbich ◽

...

Keyword(s):

Seismic Refraction ◽

Water Storage ◽

Field Studies ◽

High Mountain ◽

Rock Glacier ◽

Mountain Catchment ◽

Rock Glaciers ◽

Ice Content ◽

Surface Ice ◽

Water Contents

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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