Reconstruction of the dynamics and origin of rock glaciers in an Alpine environment

Rock glaciers are one of the most frequent cryospheric landform in mid-latitude mountain ranges. They influence the evolution of alpine environments on short (years to decades) and long (centuries to millennia) time scales. As a visible expression of mountain permafrost [1] as well as an important water reserve in the form of ground ice [2], rock glaciers are seen as increasingly important in the evolution of geomorphology and hydrology of mountain systems in the context of climate change and deglaciation [3, 4]. On longer time scales, rock glaciers transport boulders produced by the erosion of the headwall upstream and downstream and therefore participate in shaping mountain slopes [5]. Despite their importance, the dynamics and origin of rock glaciers are poorly understood.In this study, we propose to address two questions:1) How does the dynamics of rock glaciers change over time?2) What is the origin of rock glaciers and what is their influence on the evolution of alpine environments?These two questions require an evaluation of the surface velocity field of rock glaciers by relating short and long time scales. To solve this problem, we combine complementary methods including remote sensing, geochronology with a mechanical model of rock glacier dynamics. We apply this approach to the rock glacier complex of the Vallon de la Route in the Massif du Combeynot (French alps).In order to reconstruct the displacement field of the rock glacier on modern time scales, we used remote sensing methods (i.e., image correlation and InSAR). Over longer periods (103 to 104 years), we used cosmogenic terrestrial nuclides (TCN) dating. By applying this methodology to boulder surfaces at different positions along the central flow line of the rock glacier, from the headwall to its terminus, we will be able to convert the exposure ages into surface displacement. The use of dynamic modelling of rock glaciers [6] will allow us to relate the surface kinematics to short to long time scales. It will then be possible to discuss the age, origin of rock glaciers and how topo-climatic and geomorphological processes control their evolution in Alpine environment.&#160;[1] Barsch, D.: Rockglaciers. Indicators for the Present and Former Geoecology in High Mountain Environments, Springer series in physical environment vol. 16, Springer, Berlin, Heidelberg, 1996.[2] Jones, D. B., Harrison, S., Anderson, K., and Whalley, W. B.: Rock glaciers and mountain hydrology: A review, Earth-Sci Rev, 193, 66&#8211;90, 2019.[3] Haeberli, W., Schaub, Y., and Huggel, C.: Increasing risks related to landslides from degrading permafrost into new lakes in deglaciating mountain ranges, Geomorphology, 293, 405&#8211;417, 2017.[4] Knight, J., Harrison, S., and Jones, D. B.: Rock glaciers and the geomorphological evolution of deglacierizing mountains, Geomorphology, 324, 14&#8211;24, 2019.[5] MacGregor, K.R., Anderson, R.S., Waddington, E.D.: Numerical modeling of glacial erosion and headwall processes in alpine valleys. Geomorphology 103 (2):189&#8211;204, 2009.[6] Anderson, R. S., Anderson, L. S., Armstrong, W. H., Rossi, M. W., & Crump, S. E.: Glaciation of alpine valleys: The glacier&#8211;debris-covered glacier&#8211;rock glacier continuum. Geomorphology, 311, 127-142, 2018.

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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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MASS MOVEMENTS OF AN ALPINE ROCK GLACIER

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-2-w13-215-2019 ◽

2019 ◽

Vol XLII-2/W13 ◽

pp. 215-219 ◽

Cited By ~ 1

Author(s):

R. Boesch ◽

C. Graf

Keyword(s):

Motion Tracking ◽

Optical Resolution ◽

Movement Patterns ◽

Cost Effective ◽

Filter Method ◽

Rock Glacier ◽

Point Matching ◽

Alpine Environment ◽

Rock Glaciers ◽

Commercial Off The Shelf

Abstract. Rock glaciers, tonguelike bodies consisting of angular rock debris frozen in interstitial ice, may flow with velocities varying from a few centimeter up to several meters per year. Recent ground warming may generate an accelerated slope movement related to permafrost creep. Newer generations of commercial off-the-shelf drones like DJI Mavic are cost-effective, lightweight and still have a sufficient pay load reserve for flights at 2800 m.a.s.l. This allows that a two men crew can carry the necessary reference and drone equipment in a high alpine environment and a flight campaign can be conducted within one day. Using different cameras with similar optical resolution allows to generate DSMs with comparable accuracy. The DSM resolution should be 10&thinsp;cm or better to achieve robust results. Motion tracking of rock glacier with tie point matching algorithms SIFT or SURF combined with an appropriate filter method allows to distinguish different movement patterns within local neighborhood. Compared to point-wise GPS-based methods or image-based cross-correlation approaches, tie point matching allows to detect inhomogeneous movement patterns, which are typical for rock glaciers in a high alpine environment.

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Inventory of active rock glaciers in the western Nyainqêntanglha Range, Tibetan Plateau

10.5194/egusphere-egu21-2461 ◽

2021 ◽

Author(s):

Eike Reinosch ◽

Markus Gerke ◽

Björn Riedel ◽

Antje Schwalb ◽

Qinghua Ye ◽

...

Keyword(s):

Tibetan Plateau ◽

High Reliability ◽

Surface Velocity ◽

Windward Side ◽

Mountain Range ◽

The Tibetan Plateau ◽

Automated Classification ◽

Rock Glacier ◽

North West ◽

Rock Glaciers

The western Nyainq&#234;ntanglha Range on the Tibetan Plateau (TP) reaches an elevation of 7162 m and is characterized by an extensive periglacial environment. Here, we present the first rock glacier inventory of the central TP containing 1433 rock glaciers over an area of 4622 km&#178;. The rock glaciers are identified based on their surface velocity. The surface velocity is derived from Sentinel-1 satellite data of 2016 to 2019 via InSAR time series analysis. 16.4 % of the inventoried rock glaciers are classified as active with a surface velocity above 10 cmyr-1 and 80.0 % are classified as transitional with 1 to 10 cmyr-1. The western Nyainq&#234;ntanglha Range forms a climate divide between the dry continental climate brought by the Westerlies from the north-west and the Indian Summer Monsoon to the south. 89.7 % of all active rock glaciers and 74 % of the free ice glacial area are located on the southern side. The higher moisture availability on the southern (windward) side of the mountain range is likely the cause of a higher rock glacier occurrence and the greater activity.Manually identifying and outlining rock glaciers is time consuming and subjective. To ensure a high reliability and comparability of our inventory, we therefore combined a manual approach with an automated classification. Three analysts worked in tandem to generate the manual outlines according to the guidelines of the IPA action group on &#8216;Rock glacier inventories and kinematics&#8217;. A subset of these outlines acted as training areas for a pixel-based maximum likelihood classification. Both the manual and the automated classification were performed based on DEM parameters (elevation, slope etc.), optical datasets (Sentinel-2 and NDVI) and surface velocity (generated with InSAR). 87.8 % of all manually outlined rock glaciers were identified successfully at a true positive rate of 69.5 %. 18 additional rock glaciers were added to the inventory based on the automated classification. This combined approach is therefore beneficial to generate a complete inventory. The automated classification can, however, not replace the expertise of an analyst as it greatly overestimates the actual rock glacier area.

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Distribution and morpho-thermal characteristics of rock glaciers in southern Peru: case, Cordilleras Huanzo and Chila

10.5194/egusphere-egu2020-4442 ◽

2020 ◽

Author(s):

Katy Medina ◽

Edwin Loarte ◽

Edwin Badillo ◽

Hairo Leon ◽

Francisco Castillo ◽

...

Keyword(s):

Thermal Characteristics ◽

Google Earth ◽

High Mountain ◽

Rock Glacier ◽

Alos Palsar ◽

Mountain Ranges ◽

Thermal Range ◽

Tropical Glaciers ◽

The Pacific ◽

Rock Glaciers

Climate change generates significant impacts on high mountain regions, especially considering the sensitivity of tropical glaciers. However, information about rock glaciers are very scarce and there is very limited research in this field in Peru. Rock glacier concentrate mainly in the southern part of Peru where 95% of rock glaciers are located. Here we present for the first time an overview of rock glacier occurrence and characteristics in Peru.The Cordilleras Huanzo and Chila are located in the mountain ranges in the southern region of Peru, Huanzo in the administrative region of Apurimac, Arequipa, Cusco and Ayacucho, while Chila in Arequipa. Both cordilleras extend from S 15&#176;39'41.36" to 14&#176;03'17.54" and W 73&#176;24'12.55" to 71&#176;27'113.20". For this study, remote sensing tools and geographic information system were applied, using images from Google Earth-Pro and SASPlanet, corrected DEM ALOS Palsar (12.5m), MERIT DEM (90m) and WorldClim data (1970-2000) 1 km2.The results indicate that in the cordillera Huanzo there are 317 rock glaciers with a total area of 26.97 km2 and in the cordillera Chila there are 289 rock glaciers with 17.96 km2. Concerning their activity or dynamic there are 295 intact (active and inactive) rock glaciers and 311 relict or fossil rock glaciers.The results further indicate that rock glaciers are located in thermal ranges between -1.53&#176;C and 3.97&#176;C. The relict or fossil types are located in the thermal range between -1.34&#176;C and 3.97&#176;C, while intact types between -1.53&#176;C and 2.56&#176;C. The rock glaciers of the cordillera Huanzo are located at an average altitude of 4497 to 5221 m.a.s.l., while in the cordillera Chila at 4470 to 5454 m.a.s.l. The aspect is predominantly S to SW.Rock glaciers contain ice which may represent a potential water reserve in arid regions in Southern of Peru. The greatest distribution of these resources is found in the Camana and Oco&#241;a basins of the Pacific watershed with 38.1 km2 of rock glacier area. In the Atlantic watershed, 6.8 km2 of rock glaciers are located in the Alto Apurimac and Oco&#241;a basins.

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Towards accurate quantification of ice content in permafrost of the Central Andes, part I: geophysics-based estimates from three different regions

10.5194/tc-2021-206 ◽

2021 ◽

Author(s):

Christin Hilbich ◽

Christian Hauck ◽

Coline Mollaret ◽

Pablo Wainstein ◽

Lukas U. Arenson

Keyword(s):

Remote Sensing ◽

Hydrological Cycle ◽

Field Measurements ◽

Central Andes ◽

Rock Glacier ◽

Ground Ice ◽

Catchment Scale ◽

Refraction Seismic ◽

Rock Glaciers ◽

Ice Content

Abstract. In view of the increasing water scarcity in the Central Andes in response to ongoing climate change, the significance of permafrost occurrences for the hydrological cycle is currently being discussed in a controversial way. The lack of comprehensive field measurements and quantitative data on the local variability of internal structure and ground ice content further enhances the situation. We present field-based data from six extensive geophysical campaigns completed since 2016 in three different high-altitude regions of the Central Andes of Chile and Argentina (28 to 32° S). Our data cover various permafrost landforms ranging from ice-poor bedrock to ice-rich rock glaciers and are complemented by ground truthing information from boreholes and numerous test pits near the geophysical profiles. In addition to determining the thickness of the potential ice-rich layers from the individual profiles, we also use the quantitative 4-phase model to estimate the volumetric ground ice content in representative zones of the geophysical profiles. The analysis of 52 geoelectrical and 24 refraction seismic profiles within this study confirmed that ice-rich permafrost is not restricted to rock glaciers, but is also observed in non-rock-glacier permafrost slopes in the form of interstitial ice as well as layers with excess ice, resulting in substantial ice contents. Consequently, non-rock glacier permafrost landforms, whose role for local hydrology has so far not been considered in remote-sensing based approaches, may be similarly relevant in terms of ground ice content on a catchment scale and should not be ignored when quantifying the potential hydrological significance of permafrost. We state that geophysics-based estimates on ground ice content allow for more accurate assessments than purely remote-sensing-based approaches. The geophysical data can then be further used in upscaling studies to the catchment scale in order to reliably estimate the hydrological significance of permafrost within a catchment.

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Investigation on protalus ramparts in the Swiss Alps

Geographica Helvetica ◽

10.5194/gh-70-135-2015 ◽

2015 ◽

Vol 70 (2) ◽

pp. 135-139 ◽

Cited By ~ 8

Author(s):

C. Scapozza

Keyword(s):

Diagnostic Criteria ◽

Scientific Literature ◽

Swiss Alps ◽

Rock Glacier ◽

Rock Glaciers ◽

Talus Slopes ◽

Definition Of ◽

Alpine Environments ◽

Large Diffusion

Abstract. The origin and classification of landforms denominated as "protalus ramparts" in the scientific literature is a problem that is far from being resolved. The main objective of this contribution is to support a permafrost-related definition of protalus ramparts. If we consider the Alpine framework, protalus ramparts are generally very rare landforms; by contrast, the Alpine periglacial belt is characterised by a large diffusion of talus slopes and talus rock glaciers. The investigations carried out in six sites of the Valais Alps (Switzerland) allow eight major "diagnostic criteria" to be presented that help to define protalus ramparts in Alpine environments and that support the permafrost-related genesis of most of them. The major source of controversy is related to the use of the term protalus rampart to designate both a nivo-gravitational landform (also called "pronival ramparts") and a permafrost-related landform. All the considerations presented here allow an active protalus rampart to be defined simply as a (small) active talus rock glacier.

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Towards accurate quantification of ground ice content in permafrost of the Central Andes: geophysics-based estimates from three different regions

10.5194/egusphere-egu21-12553 ◽

2021 ◽

Author(s):

Christin Hilbich ◽

Tamara Mathys ◽

Christian Hauck ◽

Lukas Arenson

Keyword(s):

Remote Sensing ◽

Central Andes ◽

The Other ◽

Data Sets ◽

Rock Glacier ◽

Ground Ice ◽

Other Hand ◽

Rock Glaciers ◽

Ice Content ◽

Permafrost Regions

Continued climate change is projected to cause significant temperature increase, yielding substantial water shortage especially in the semi-arid mountain regions of the Central Andes. The role of permafrost occurrences for the hydrological cycle in the Central Andes is currently discussed in a controversial way. On the one hand, permafrost in general, and especially rock glaciers are considered key stores of frozen water in view of the recession of glaciers, and degrading permafrost is expected to partly compensate the decreasing glacial discharge in future. On the other hand, the methodology to quantify ground ice resources in Andean permafrost regions as well as the time scales involved for significant discharge from permafrost bodies are currently disputed.Comprehensive and quantitative field-based data on the local variability of internal structure, ground ice content and the hydrological contribution of different permafrost landforms are mostly lacking, and the current debate mostly focuses on rock glaciers as the prominent ice-rich permafrost landforms, as they can easily be identified by remote sensing.To ameliorate this lack of ground truth data, we present a quantitative analysis of > 50 Electrical Resistivity Tomography and > 20 Refraction Seismic Tomography profiles from several permafrost sites in different geomorphologic settings, including ice-rich and ice-poor permafrost occurrences. The surveys were conducted between 2016 and 2019 in three different regions of the Central Andes of Chile and Argentina (28 - 32&#176; S) in the framework of several Baseline studies in mining environments. For some sites borehole and test pit data are available and used to validate the quantitative estimates of ground ice contents by the 4-phase model (Hauck et al. 2011).We demonstrate the value of geophysical surveys to detect ice-rich permafrost in various landforms (also beyond rock glaciers), and to estimate ground ice volumes in permafrost regions. Our data show, that remote-sensing based approaches tend to significantly overestimate ice volumes of rock glaciers, and on the other hand, that ice-rich permafrost is not restricted to rock glaciers, but also observed in non-rock-glacier permafrost slopes in the form of interstitial ice and layers with excess ice. In regions with widespread occurrence of such permafrost slopes, even relatively thin ice-rich layers can sum up to substantial total ground ice contents, which can be close to the volumes observed in rock glaciers. Consequently, non-rock-glacier permafrost terrain, whose role for local hydrology is basically neglected in remote-sensing based approaches, may be of equal hydrological significance regarding stored ground ice volumes on the catchment scale in some cases, and shall not be ignored.The presented data may therefore serve as one of the first available field-based and validated data sets regarding the presence and total quantities of ground ice, and as input for modelling studies about the relative contributions of rock glacier and non-rock glacier permafrost to runoff in the Central Andes.&#160;ReferencesHauck C, B&#246;ttcher M and Maurer H 2011. A new model for estimating subsurface ice content based on combined electrical and seismic data sets. The Cryosphere 5(2): 453-468.

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Use of Convolution Neural Networks and Object Based Image Analysis for Automated Rock Glacier Mapping

10.5194/egusphere-egu2020-9201 ◽

2020 ◽

Author(s):

Benjamin Aubrey Robson ◽

Tobias Bolch ◽

Shelley MacDonell ◽

Daniel Hölbling ◽

Philip Rastner ◽

...

Keyword(s):

Remote Sensing ◽

Neural Networks ◽

Image Analysis ◽

Deep Learning ◽

Image Resolution ◽

Rock Glacier ◽

Object Based Image Analysis ◽

Object Based ◽

Rock Glaciers ◽

The Creation

Rock glaciers are an important, but often overlooked, component of the cryosphere and are one of the few visible manifestations of permafrost. In certain parts of the world, rock glaciers can contribute up to 30% of catchment streamflow. Remote sensing has permitted the creation of rock glacier inventories for large regions, however, due to the spectral similarity between rock glaciers and the surrounding material, the creation of such inventories is typically conducted based on manual interpretation of remote sensing data which is both time consuming and subjective. Here, we present a method that combines deep learning (convolutional neural networks or CNNs) and object-based image analysis (OBIA) into one workflow based on freely available Sentinel-2 imagery, Sentinel-1 interferometric coherence, and a Digital Elevation Model. CNNs work by identifying recurring patterns and textures and produce a heatmap where each pixel indicates the probability that it belongs to a rock glacier or not. By using OBIA we can segment the datasets and classify objects based on their heatmap value as well as morphological and spatial characteristics and convert the raw probability heatmap generated by the deeo learning into rock glacier polygons. We analysed two distinct catchments, the La Laguna catchment in the Chilean semi-arid Andes and the Poiqu catchment on the Tibetan Plateau. In total, our method mapped 72% of the rock glaciers across both catchments, although many of the individual rock glacier polygons contained false positives that are texturally similar, such as debris-flows, avalanche deposits, or fluvial material causing the user&#8217;s accuracy to be moderate (64-69%) even if the producer&#8217;s accuracy was higher (75%). We repeated our method on very-high resolution Pl&#233;iades satellite imagery (resampled to 2 m resolution) for a subset of the Poiqu catchment to ascertain what difference the image resolution makes. We found that working at a higher spatial resolution has little influence on the user&#8217;s accuracy (an increase of 3%) yet as smaller landforms were mapped, the producer&#8217;s accuracy rose by 13% to 88%. By running all the processing within an object-based analysis it was possible to both generate the deep learning heatmap and automate some of the post-processing through image segmentation and object reshaping. Given the difficulties in differentiating rock glaciers using image spectra, deep learning offers a feasible method for automated mapping of rock glaciers over large regional scales.

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The Spread of Pollutants from Harbour Sludge Depots

Water Science & Technology ◽

10.2166/wst.1984.0096 ◽

1984 ◽

Vol 16 (3-4) ◽

pp. 623-633

Author(s):

M Loxham ◽

F Weststrate

Keyword(s):

Time Scales ◽

Molecular Diffusion ◽

Near Field ◽

Parameter Analysis ◽

Migration Patterns ◽

Long Time ◽

Dilution Effects ◽

Short Time ◽

Harbour Sludge

It is generally agreed that both the landfill option, or the civil techniques option for the final disposal of contaminated harbour sludge involves the isolation of the sludge from the environment. For short time scales, engineered barriers such as a bentonite screen, plastic sheets, pumping strategies etc. can be used. However for long time scales the effectiveness of such measures cannot be counted upon. It is thus necessary to be able to predict the long term environmenttal spread of contaminants from a mature landfill. A model is presented that considers diffusion and adsorption in the landfill site and convection and adsorption in the underlaying aquifer. From a parameter analysis starting form practical values it is shown that the adsorption behaviour and the molecular diffusion coefficient of the sludge, are the key parameters involved in the near field. The dilution effects of the far field migration patterns are also illustrated.

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Remote Sensing Monitoring of Advancing and Surging Glaciers in the Tien Shan, 1990–2019

Remote Sensing ◽

10.3390/rs13101973 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1973

Author(s):

Sugang Zhou ◽

Xiaojun Yao ◽

Dahong Zhang ◽

Yuan Zhang ◽

Shiyin Liu ◽

...

Keyword(s):

Remote Sensing ◽

Landsat Tm ◽

Tien Shan ◽

High Latitudes ◽

Remote Sensing Images ◽

Climate Variable ◽

Mountain Ranges ◽

Remote Sensing Monitoring ◽

Change Mechanism ◽

Temperature And Precipitation

The advancing of glaciers is a manifestation of dynamic glacial instability. Glaciers in the Tien Shan region, especially in the Central Tien Shan, show instability, and advancing glaciers have been recently detected. In this study, we used Landsat TM/ETM+/OLI remote sensing images to identify glaciers in the Tien Shan region from 1990 to 2019 and found that 48 glaciers advanced. Among them, thirty-four glaciers exhibited terminal advances, and 14 glaciers experienced advances on the tributary or trunk. Ten of the glaciers experiencing terminal advances have been identified as surging glaciers. These 48 glaciers are distributed in the western part of the Halik and Kungey Mountain Ranges in the Central Tien Shan, and Fergana Mountains in the Western Tien Shan, indicating that the Tien Shan is also one of the regions where advancing and surging glaciers are active. From 1990 to 2019, a total of 169 times advances occurred on 34 terminal advancing glaciers in the Tien Shan region; the highest number of advancing and surging of glaciers occurred in July (26 and 14 times, respectively). With reference to the existing literature and the present study, the surge cycle in the Tien Shan is longer than that in other regions at high latitudes in Asia, lasting about 35–60 years. Surging glaciers in the Tien Shan region may be affected by a combination of thermal and hydrological control. An increase in temperature and precipitation drives surging glaciers, but the change mechanism is still difficult to explain based on changes in a single climate variable, such as temperature or precipitation.

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