Kinematics of an Alpine rock glacier from multi-temporal UAV surveys and GNSS data

Bearzot, Francesca; Garzonio, Roberto; Mauro, Biagio Di; Colombo, R.; Cremonese, Edoardo; Crosta, Giovanni B.; Delaloye, Reynald; Hauck, Christian; Cella, Umberto Morra di; Pogliotti, Paolo; Frattini, Paolo; Rossini, Micol

doi:10.1016/j.geomorph.2022.108116

Cited by 22 publications

(25 citation statements)

References 40 publications

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“…The applied method was exploratory and might suffer some deficiencies. However, the order of magnitude of the subsidence rate due to the melting of excess ice estimated on Aget GFL A fits with observations made recently on various rock glaciers in the European Alps 51,53,54 …”

Section: Discussionsupporting

confidence: 82%

Post‐glacial dynamics of an alpine Little Ice Age glacitectonized frozen landform (Aget, western Swiss Alps)

Wee

Delaloye

2022

Permafrost & Periglacial

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Glaciers and frozen‐debris landforms have coexisted and episodically or continuously interacted throughout the Holocene at elevations where the climate conditions are cold enough for permafrost to occur. In the European Alps, the Little Ice Age (LIA) characterized the apogee of the last interaction phase. In areas of consecutive post‐LIA glacier shrinkage, the geomorphological dominant conditioning of the ongoing paraglacial phase may have transitioned from glacial to periglacial and later even shifted to post‐periglacial. Such transitions can be observed through the morphodynamics of glacitectonized frozen landforms (GFLs), which are permafrost‐related pre‐existing frozen masses of debris deformed (tectonized) by the pressure exerted by an interacting glacier. This contribution aims at evidencing the processes driving the ongoing morphodynamical evolution of an actively back‐creeping GFL within the LIA forefield of the Aget glacier on the basis of long‐term time series of ground surface temperature, and in‐situ geodetic and geoelectrical measurements. Our observations for the last two decades (1998–2020), which have been the warmest since the LIA, reveal a resistivity decrease in the permafrost body and a surface subsidence of up to a few centimeters per year. The former indicate a liquid water‐to‐ice content ratio increase within the permafrost body and the latter a ground ice melt at the permafrost table, both processes having taken place heterogeneously at the scale of the landform. The absence of acceleration of landform motion during that period despite a probable warming trend of the frozen ground may indicate that the ongoing degradation is reaching a tipping point at which processes related to interparticle friction and thinning of the permafrost body contribute to gradually inactivate the mechanism of permafrost creep.

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Section: Discussionsupporting

confidence: 82%

Post‐glacial dynamics of an alpine Little Ice Age glacitectonized frozen landform (Aget, western Swiss Alps)

Wee

Delaloye

2022

Permafrost & Periglacial

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“…As such, the so-called UAV-SfM photogrammetric workflows have been used in different domains, such as the monitoring of landslide kinematics (Lucieer et al, 2013;Clapuyt et al, 2017) and for studying glacial (Ryan et al, 2015;Fugazza et al, 2018;Rossini et al, 2018;Benoit et al, 2019) and periglacial processes (Eichel et al, 2020;Hendrickx et al, 2020), among other applications. Until now, only a few study cases have reported on rock glacier monitoring by relying exclusively on UAV-SfM techniques (Dall'Asta et al, 2017;Vivero and Lambiel, 2019;Halla et al, 2021;Bearzot et al, 2022) or by a combination of UAV-SfM with additional remote sensing data (Kaufmann et al, 2018;Groh and Blöthe, 2019;Fey and Krainer, 2020;Blöthe et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Kinematics and geomorphological changes of a destabilising rock glacier captured from close-range sensing techniques (Tsarmine rock glacier, Western Swiss Alps)

et al. 2022

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Accurately assessing landform evolution and quantifying rapid environmental changes are gaining importance in the context of monitoring techniques in alpine environments. In the European Alps, glaciers and rock glaciers are among the most characteristic cryospheric components bearing long and systematic monitoring periods. The acceleration in rock glacier velocities and the onset of destabilization processes, mainly since 1990, have raised several concerns due to the potential effects on the high alpine natural and anthropic environments. This study presents a combination of uncrewed aerial vehicle (UAV) and terrestrial laser scanning (TLS) surveys for monitoring the current changes on the quickly accelerating, destabilised Tsarmine rock glacier in the Arolla Valley, Western Swiss Alps, delivering a considerable volume of debris to a steep torrential gully. High-resolution digital elevation models (DEMs) and orthomosaics are derived from UAV image series combined with structure from motion (SfM) photogrammetry techniques. Multitemporal orthomosaics are employed for measuring spatially continuous rock glacier kinematics using image matching algorithms. Superficial displacements are evaluated with simultaneous in-situ differential global navigation satellite system (GNSS) measurements. Elevation and volume changes are computed from TLS and UAV-derived DEMs at similar periods. Between June 2017 and September 2019, both datasets showed a similar elevation change pattern and surface thinning rates of 0.15 ± 0.04 and 0.16 ± 0.03 m yr−1, respectively. Downward of a rupture zone developing about 150 m above the front, the rock glacier doubled its overall velocity during the study period, from around 5 m yr−1 between October 2016 and June 2017 to more than 10 m yr−1 between June and September 2019. The kinematic information reveals striking differences in the velocity between the lower and upper rock glacier sections. The monitoring approach based on close-sensing techniques provides accurate surface velocity and volume change information, allowing an enhanced description of the current rock glacier dynamics and its surface expression.

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“…Adopting a plastic model for the rock glacier thickness and standard values of the material parameters (ω i = 0.7, ρ = 1500 kg m −3 , Ø = 25 • , τ cθ = 10 kPa, n = 2.1 and . γc = 0.06 a −1 ) [17], the formulation of the BCF can be approximated to:…”

Section: The Bulk Creep Factor and Applicabilitymentioning

confidence: 99%

“…Some studies of rock glacier dynamics concentrate on surface displacements and morphology changes [15][16][17], whereas some other on their internal structure [13,18,19] and liquid water content [12], trying to understand the factors that force rock glacier responses across different temporal and spatial scales.…”

Section: Introductionmentioning

confidence: 99%

Flow Velocity Variations and Surface Change of the Destabilised Plator Rock Glacier (Central Italian Alps) from Aerial Surveys

et al. 2022

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Flow velocities were measured on the Plator rock glacier in the Central Italian Alps using a correlation image analysis algorithm on orthophotos acquired by drones between the years 2016 and 2020. The spatial patterns of surface creep were then compared to the Bulk Creep Factor (BCF) spatial variability to interpret the rock glacier dynamics as a function of material properties and geometry. The rock glacier showed different creep rates in the rooting zone (0.40–0.90 m/y) and in the frontal zone (>4.0 m/y). Close to the rock glacier front, the BCF assumed the highest values, reaching values typical of rock glaciers experiencing destabilisation. Conversely, in the rooting zone the small rates corresponded to lowest BCFs, about five times smaller than in the frontal zone. The Plator rock glacier revealed a substantial advancement from 1981 to 2020 and distinct geomorphological features typical of rock glaciers exhibiting destabilising processes. Given the fast-moving phase, the advancement of both the front line and the front toe of the rock glacier, and the contrasting spatial distribution in the BCFs, the Plator could be considered a destabilised rock glacier.

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Kinematics of an Alpine rock glacier from multi-temporal UAV surveys and GNSS data

Cited by 22 publications

References 40 publications

Post‐glacial dynamics of an alpine Little Ice Age glacitectonized frozen landform (Aget, western Swiss Alps)

Post‐glacial dynamics of an alpine Little Ice Age glacitectonized frozen landform (Aget, western Swiss Alps)

Kinematics and geomorphological changes of a destabilising rock glacier captured from close-range sensing techniques (Tsarmine rock glacier, Western Swiss Alps)

Flow Velocity Variations and Surface Change of the Destabilised Plator Rock Glacier (Central Italian Alps) from Aerial Surveys

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