Investigation of rock and ice loss in a recently deglaciated mountain rock wall using terrestrial laser scanning: Gemsstock, Swiss Alps

Kenner, Robert; Phillips, Marcia; Danioth, C.; Denier, C.; Thee, P.; Zgraggen, A.

doi:10.1016/j.coldregions.2011.04.006

Cited by 68 publications

(60 citation statements)

References 14 publications

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“…Near-surface freeze-thaw cycles take place in autumn and late spring and seasonal frost occurs down to a depth of 8 m on the N side. Gemsstock is located at the lower fringe of permafrost and is additionally affected by ongoing retreat of the Gurschen glacier on the northern side, which makes it susceptible to rock slope failure (Kenner et al, 2011).…”

Section: Study Sitementioning

confidence: 99%

Snow as a driving factor of rock surface temperatures in steep rough rock walls

Haberkorn

Hoelzle

Phillips

et al. 2015

Cold Regions Science and Technology

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Observations show that considerable amounts of snow can accumulate in steep, rough rock walls. The heterogeneously distributed snow cover significantly affects the surface energy balance and hence the thermal regime of the rock walls. To assess the small-scale variability of snow depth and rock temperatures in steep north and south facing rock walls, a spatially distributed multi-method approach is applied at Gemsstock, Switzerland, combining 35 continuous near-surface rock temperature measurements, high resolution snow depth observations using terrestrial laser scanning, as well as in-situ snow pit investigations. The thermal regime of the rock surface is highly dependent on short-and longwave radiation, albedo, surface roughness, snow depth and on snow distribution in time and space. Around 2 m of snow can accumulate on slopes with angles up to 75°, due to micro-topographic structures like ledges. Hence, contrasts in mean annual rock surface temperature between the north and the south facing slopes are less than 4°C. However, significant small-scale variability of up to 10°C in mean daily rock surface temperature occurs within a few metres over the rock walls due to the variable snow distribution, revealing the heterogeneity and complexity of the thermal regime at a very local scale. In addition, multiple linear regression could explain up to 77% of near-surface rock temperature variability, which underlines the importance of radiation and snow depth and thus also of the topography. In the rock faces the thermal insulation of the ground starts with snow depths exceeding 0.2 m. This is due to the high thermal resistance of a less densely packed snow cover, especially in the north facing slope. Additionally, aspect induced differences of snow cover characteristics and consequently thermal conductivities are observed in the rock walls.

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Section: Study Sitementioning

confidence: 99%

Snow as a driving factor of rock surface temperatures in steep rough rock walls

Haberkorn

Hoelzle

Phillips

et al. 2015

Cold Regions Science and Technology

View full text Add to dashboard Cite

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“…In the last years, laser-based technologies have been applied with the aim of quantifying the displacement and dynamic of rock glaciers from terrestrial devices (i.e., Terrestrial Laser Scanner: TLS, e.g., [22,23,[29][30][31]) or aerial platforms (Airborne Laser Scanning: ALS, e.g., [32][33][34][35]). The use of these modern instruments produced more accurate and denser datasets with less logistical efforts and time, leading to lower costs and greater quality of field surveys [22].…”

Section: Introductionmentioning

confidence: 99%

Comparing Two Photo-Reconstruction Methods to Produce High Density Point Clouds and DEMs in the Corral del Veleta Rock Glacier (Sierra Nevada, Spain)

et al. 2014

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Abstract:In this paper, two methods based on computer vision are presented in order to produce dense point clouds and high resolution DEMs (digital elevation models) of the Corral del Veleta rock glacier in Sierra Nevada (Spain). The first one is a semi-automatic 3D photo-reconstruction method (SA-3D-PR) based on the Scale-Invariant Feature Transform algorithm and the epipolar geometry theory that uses oblique photographs and camera calibration parameters as input. The second method is fully automatic (FA-3D-PR) and is based on the recently released software 123D-Catch that uses the Structure from Motion and MultiView Stereo algorithms and needs as input oblique photographs and some measurements in order to scale and geo-reference the resulting model. The accuracy of the models was tested using as benchmark a 3D model registered by means of a Terrestrial Laser Scanner (TLS). The results indicate that both methods can be applied to micro-scale study of rock glacier morphologies and processes with average distances to the TLS point cloud of 0.28 m and 0.21 m, for the SA-3D-PR and the FA-3D-PR methods, respectively. The performance of the models was also tested by means of the dimensionless relative precision ratio parameter resulting in figures of 1:1071 and 1:1429 for the SA-3D-PR and the FA-3D-PR methods, respectively. Finally, Digital Elevation Models (DEMs) of the study area were produced and compared with the TLS-derived DEM. The

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“…As described in Kenner et al (2011), the LOS of surface movements is highly dependent on the spatial extent of the movement. The larger the extent of a movement, the higher the LOS of the movement signal in the difference-raster (spatial out-filtering of errors).…”

Section: Accuracy Analysis 431 Accuracy Of Vertical Movementsmentioning

confidence: 99%

“…Subsequently the scans were geo-referenced using the coordinates of the targets. Relative iterative-closest-point (ICP) referencing was additionally applied in a few cases due to the presence of differential orientation errors within single scans (Kenner et al, 2011). In the next step, elevation rasters were generated from the ALS/TLS point clouds.…”

Section: Vertical Movementsmentioning

confidence: 99%