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

2020 ◽  
Author(s):  
Andreas Kääb ◽  
Tazio Strozzi ◽  
Tobias Bolch ◽  
Rafael Caduff ◽  
Håkon Trefall ◽  
...  
Keyword(s):  
Sediment Transport ◽  
High Resolution ◽  
Tien Shan ◽  
Spatial And Temporal Variability ◽  
European Alps ◽  
Rock Glacier ◽  
Study Region ◽  
Rock Glaciers ◽  
The 1950S ◽  
Northern Tien Shan

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.

scholarly journals Inventory and changes of rock glacier creep speeds in Ile Alatau and Kungöy Ala-Too, northern Tien Shan, since the 1950s

2021 ◽  
Vol 15 (2) ◽  
pp. 927-949
Author(s):  
Andreas Kääb ◽  
Tazio Strozzi ◽  
Tobias Bolch ◽  
Rafael Caduff ◽  
Håkon Trefall ◽  
...  
Keyword(s):  
High Resolution ◽  
Tien Shan ◽  
Spatial And Temporal Variability ◽  
European Alps ◽  
Material Transport ◽  
Rock Glacier ◽  
Study Region ◽  
Rock Glaciers ◽  
The 1950S ◽  
Northern Tien Shan

Abstract. Spatio-temporal patterns related to the viscous creep in perennially frozen sediments of rock glaciers in cold mountains have rarely been studied outside the densely populated European Alps. This study investigates the spatial and temporal variability of rock glacier movement in the Ile Alatau and Kungöy Ala-Too mountain ranges, northern Tien Shan, a region with particularly large and fast rock glaciers. Over the study region of more than 3000 km2, an inventory of slope movements was constructed using a large number of radar interferograms and high-resolution optical imagery. The inventory includes more than 900 landforms, of which around 550 were interpreted as rock glaciers. Out of the active rock glaciers inventoried, 45 are characterized by a rate of motion exceeding 100 cm/a. From these fast rock glaciers we selected six (Gorodetzky, Morenny, Archaly, Ordzhonikidze, Karakoram, and Kugalan Tash) and studied them in more detail using offset tracking between repeat aerial images and historical and modern high-resolution optical satellite data. Two of these rock glaciers showed a steady increase in decadal surface velocities from the 1950s onwards, with speeds being roughly 2 to 4 times higher in recent years compared to the 1950s and 1960s. Three rock glaciers showed similar accelerations over the last 1 to 2 decades but also phases of increased speeds in the 1960s. This development indicates a possible significant increase in current sediment and ice fluxes through rock glaciers and implies that their material transport in the region might gain geomorphodynamic importance relative to material transport by glaciers, assuming the latter decreases together with the regional glacier shrinkage. The study demonstrates how air and satellite image archives are exploited to construct one of the longest decennial times series of rock glacier speeds currently available. Our results are in line with findings from Europe about rock glacier speeds increasing with atmospheric warming and underline local variability of such an overall response.

scholarly journals Glacier and Rock Glacier changes since the 1950s in the La Laguna catchment, Chile

2021 ◽  
Author(s):  
Benjamin Aubrey Robson ◽  
Shelley MacDonell ◽  
Álvaro Ayala ◽  
Tobias Bolch ◽  
Pål Ringkjøb Nielsen ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Balance ◽  
Shuttle Radar Topography Mission ◽  
Airborne Lidar ◽  
Rock Glacier ◽  
Glacier Changes ◽  
Elevation Changes ◽  
Rock Glaciers ◽  
The 1950S ◽  
Glacial Landforms

Abstract. Glaciers and rock glaciers play an important role in the hydrology of the semi-arid Northern Chile. Several studies show that glaciers have strongly lost mass in response to climate change during the last decades. The response to rock glaciers in this region is, however, much less investigated. In this study we use a combination of historical aerial photography, stereo satellite imagery, airborne LiDAR, and the Shuttle Radar Topography Mission (SRTM) DEM to report glacier changes for the Tapado Glacier-Rock Glacier complex from the 1950s to 2020 and to report mass balances for the glacier component of the complex, Tapado Glacier. Furthermore, we examine high-resolution elevation changes and surface velocities between 2012 and 2020 for 40 rock glaciers in La Laguna catchment. Our results show how the glacier has lost 25.2 ± 4.6 % of its ice covered area between 1956 and 2020, while the mass balance of Tapado Glacier has become steadily more negative, from being approximately in balance between 1956 and 1978 (−0.04 ± 0.08 m w.e. a−1) to showing strong losses between 2015 and 2020 (−0.32 ± 0.08 m w.e. a−1). Climatological (re)-analyses reveal a general increase in air temperature, decrease in humidity, and variable precipitation since the 1980s in the region. In particular the severe droughts in the region starting in 2010 resulted in a particular negative mass balance of −0.54 ± 0.10 m w.e. a−1 between 2012 and 2015. The rock glaciers within La Laguna catchment show heterogenous changes with some sections of landforms exhibiting pronounced elevation changes and surface velocities exceeding that of Tapado Glacier. This could be indicative of high ice contents within the landforms and also highlights the importance of considering how landforms can transition from more glacial landforms to more periglacial features under permafrost conditions. As such, we believe high-resolution (sub-metre) elevation changes and surface velocities are a useful first step for identifying ice-rich landforms.

60 years of rock glacier displacements and fluxes changes over Laurichard Rock glacier, French Alps.

2020 ◽  
Author(s):  
Diego Cusicanqui ◽  
Antoine Rabatel ◽  
Xavier Bodin
Keyword(s):  
Time Series ◽  
Mass Transport ◽  
Surface Flow ◽  
Aerial Images ◽  
Surface Elevation ◽  
European Alps ◽  
Rock Glacier ◽  
French Alps ◽  
High Resolution Satellite Images ◽  
Rock Glaciers

<p>Recent acceleration of rock glaciers has been largely documented in the European Alps, hence highlighting an increase in flow speed of stable rock glaciers and some anomalous behaviors called destabilization (development of landslides-like features on the rock glacier surface).  In this study, we focus on Laurichard active rock glacier, 225 m long, up to 75 m wide, which covers an area of 0.084 km2 and has the longest measurement time-series in the French Alps. Here we aim to understand the causes of the changes in ice velocity of Laurichard rock glacier. We investigate the changes in the fluxes of ice masses across longitudinal and transversal profiles in order to be able to analyze in details the differences between the upper part and the front of the glacier. Using a combination of remote sensing data from 1952 (historical aerial images) until 2018 (Pléiades high-resolution satellite images), we documented the three-dimensional evolution of the Laurichard rock glacier during the last 60 years. We calculated the surface flow velocity between 1952 and 2018 using a feature-tracking algorithm at a resolution of 1 m and a precision of 0.5 m. Digital elevation models were assembled using the SfM techniques for aerial images, and the AMES stereo pipeline for Pléiades data. In addition, we made the analysis using in-situ annual velocities and temperatures data allowing to understand better which factors mostly explain the kinematic behavior.  We reconstructed a time series of changes in surface elevation by systematically co-registering and differencing DEMs between 1952 and 2018, with an average precision of 1 m. We first observed that the average annual horizontal velocity measured had increased progressively from 0.65 m yr<sup>-1</sup> to 1.1 m yr<sup>-1</sup> to 1.5 m yr<sup>-1</sup> for the periods 1952-1960, 1994-2003 and 2013-2018, respectively. On the other hand, the surface mass changes and long term monitoring of mass transport show for all analyzed periods a clear negative surface elevation change of 2 m on average, between 1952 and 2018. The area with most of the elevation changes is the frontal part of the glacier, which is consistent with the increase in speed, which represents a mass exchange from the upper part to the front. We conclude that the rates of rock glacier mass transport have increased during the last 20 years and hypothetize, for this rock glacier, a transition state controlled mainly by local topographical factors which will eventually lead to high speed rock glacier or rock glacier destabilization.</p>

scholarly journals Contrasting physical and chemical conditions of two springs fed by active rock glaciers

2020 ◽  
Author(s):  
Stefano Brighenti ◽  
Michael Engel ◽  
Monica Tolotti ◽  
Maria Bruno ◽  
Geraldene Wharton ◽  
...  
Keyword(s):  
Trace Elements ◽  
Water Temperature ◽  
Major Ions ◽  
Quantitative Description ◽  
European Alps ◽  
Rock Glacier ◽  
Rainfall Events ◽  
Rock Glaciers ◽  
Chemical Conditions ◽  
Physical And Chemical

Rock glaciers are increasingly influencing the hydrology and water chemistry of Alpine catchments, with important implications for drinking water quality and ecosystem health under a changing climate. During summers of 2017 - 2019, we monitored the physical and chemical conditions of springs emerging from two active rock glaciers (ZRG and SRG) with distinct geomorphological settings in the Eastern Italian Alps (Solda/Sulden catchment). Both springs had constantly cold waters (1.4 ± 0.1 °C), and their ionic composition was dominated by SO42-, HCO3-, Ca2+ and Mg2+. Concentrations of major ions and trace elements, and values of water isotopes (δ18O, δ2H), increased towards autumn with an asymptotic trend at SRG, and a positive unimodal pattern at ZRG, where concentrations peaked 60 - 80 days after the end of the snowmelt. Wavelet analysis on electrical conductivity (EC) and water temperature records revealed daily cycles only at SRG, and significant weekly/biweekly fluctuations at both springs attributable to oscillations of meteorological conditions. Several rainfall events triggered a transient (0.5 - 2 hrs) EC drop and water temperature rise (dilution and warming) at SRG, whereas only intense rainfall events occasionally increased EC at ZRG (solute enrichment and thermal buffering), with a long-lasting effect (6 - 48 hrs). Our results, supported by a limited but emerging literature, suggest that: i) the distinctive composition of the bedrock drives different concentrations of major ions and trace elements in rock glacier springs; ii) pond-like and stream-like springs have distinct fluctuations of water parameters at different timescales; iii) peaks of EC/solute concentrations indicate a seasonal window of major permafrost thaw for rock glaciers feeding pond-like springs. These results provide a first quantitative description of the hydrological seasonality in rock glacier outflows, and their hydrochemical response to precipitation events, bringing relevant information for water management in the European Alps under climate change.

scholarly journals Mapping and inventorying active rock glaciers in the northern Tien Shan of China using satellite SAR interferometry

2017 ◽  
Vol 11 (2) ◽  
pp. 997-1014 ◽  
Author(s):  
Xiaowen Wang ◽  
Lin Liu ◽  
Lin Zhao ◽  
Tonghua Wu ◽  
Zhongqin Li ◽  
...  
Keyword(s):  
Quantitative Information ◽  
Google Earth ◽  
Tien Shan ◽  
Sar Interferometry ◽  
Western China ◽  
Mountain Ranges ◽  
Optical Images ◽  
Rock Glaciers ◽  
Altitudinal Limit ◽  
Northern Tien Shan

Abstract. Rock glaciers are widespread in the Tien Shan. However, rock glaciers in the Chinese part of the Tien Shan have not been systematically investigated for more than 2 decades. In this study, we propose a new method that combines SAR interferometry and optical images from Google Earth to map active rock glaciers (ARGs) in the northern Tien Shan (NTS) of China. We compiled an inventory that includes 261 ARGs and quantitative information about their locations, geomorphic parameters, and downslope velocities. Our inventory shows that most of the ARGs are moraine-derived (69 %) and facing northeast (56 %). The altitude distribution of ARGs in the western NTS is significantly different from those located in the eastern part. The downslope velocities of the ARGs vary significantly in space, with a maximum of about 114 cm yr−1 and a mean of about 37 cm yr−1. Using the ARG locations as a proxy for the extent of alpine permafrost, our inventory suggests that the lowest altitudinal limit for the presence of permafrost in the NTS is about 2500–2800 m, a range determined by the lowest ARG in the entire inventory and by a statistics-based estimation. The successful application of the proposed method would facilitate effective and robust efforts to map rock glaciers over mountain ranges globally. This study provides an important dataset to improve mapping and modeling permafrost occurrence in vast western China.

scholarly journals An Unsupervised Method to Detect Rock Glacier Activity by Using Sentinel-1 SAR Interferometric Coherence: A Regional-Scale Study in the Eastern European Alps

2019 ◽  
Vol 11 (14) ◽  
pp. 1711 ◽  
Author(s):  
Aldo Bertone ◽  
Francesco Zucca ◽  
Carlo Marin ◽  
Claudia Notarnicola ◽  
Giovanni Cuozzo ◽  
...  
Keyword(s):  
Regional Scale ◽  
Independent Set ◽  
Unsupervised Classification ◽  
Mountainous Area ◽  
European Alps ◽  
Eastern European ◽  
Rock Glacier ◽  
Subjective Analysis ◽  
Regular Kernel ◽  
Rock Glaciers

Rock glaciers are widespread periglacial landforms in mountain regions like the European Alps. Depending on their ice content, they are characterized by slow downslope displacement due to permafrost creep. These landforms are usually mapped within inventories, but understand their activity is a very difficult task, which is frequently accomplished using geomorphological field evidences, direct measurements, or remote sensing approaches. In this work, a powerful method to analyze the rock glaciers’ activity was developed exploiting the synthetic aperture radar (SAR) satellite data. In detail, the interferometric coherence estimated from Sentinel-1 data was used as key indicator of displacement, developing an unsupervised classification method to distinguish moving (i.e., characterized by detectable displacement) from no-moving (i.e., without detectable displacement) rock glaciers. The original application of interferometric coherence, estimated here using the rock glacier outlines as boundaries instead of regular kernel windows, allows describing the activity of rock glaciers at a regional-scale. The method was developed and tested over a large mountainous area located in the Eastern European Alps (South Tyrol and western part of Trentino, Italy) and takes into account all the factors that may limit the effectiveness of the coherence in describing the rock glaciers’ activity. The activity status of more than 1600 rock glaciers was classified by our method, identifying more than 290 rock glaciers as moving. The method was validated using an independent set of rock glaciers whose activity is well-known, obtaining an accuracy of 88%. Our method is replicable over any large mountainous area where rock glaciers are already mapped and makes it possible to compensate for the drawbacks of time-consuming and subjective analysis based on geomorphological evidences or other SAR approaches.

scholarly journals Inferring the destabilization susceptibility of mountain permafrost in the French Alps using an inventory of destabilized rock glaciers

2018 ◽  
Author(s):  
Marco Marcer ◽  
Charlie Serrano ◽  
Alexander Brenning ◽  
Xavier Bodin ◽  
Jason Goetz ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Regional Scale ◽  
Susceptibility Map ◽  
Rock Glacier ◽  
Study Region ◽  
Support Tool ◽  
French Alps ◽  
Terrain Attributes ◽  
Rock Glaciers ◽  
Deformation Patterns

Abstract. Knowing the extent of degrading permafrost is a key issue in the context of emerging risks linked to climate change. In the present study we propose a methodology to estimate the spatial distribution of this phenomenon, focusing on the French Alps. At first, using recent orthoimages (2000 to 2013) covering the study region, we mapped the geomorphological features that can be typically found in cases of rock glacier destabilization (e.g. crevasses and scarps). This database was then used as support tool to rate rock glaciers destabilization. The destabilization rating was assigned also taking into account the surface deformation patterns of the rock glacier, observable by comparing the orthoimages. The destabilization rating served as database to model the occurrence of destabilization in relation to terrain attributes and to predict the susceptibility to destabilization at the regional scale. Potential destabilization could be observed in 58 rock glaciers, i.e. 12  of the total active rock glaciers in the region. Potentially destabilized rock glaciers were found to be more prone to strong acceleration than stable rock glaciers within the period 2000–2013. Modelling the occurrence of destabilization suggested that this phenomenon is more likely to occur in elevations around the 0 °C isotherm (2700–2900 m.s.l.), on north-exposed, steep (up to 30°) and flat to slightly convex topographies. Model performances were good (AUROC: 0.76) and the susceptibility map reproduced well the observable patterns. About 3 km2 of creeping permafrost, i.e. 10 % of the surface occupied by active rock glaciers, had a high susceptibility to destabilization. Only half of this surface is currently showing destabilization evidence, suggesting that a significant amount of rock glaciers are candidates for future destabilization.

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