Low-altitude permafrost research in an overcooled talus slope–rock glacier system in the Romanian Carpathians (Detunata Goală, Apuseni Mountains)

Popescu, Răzvan; Vespremeanu‐Stroe, Alfred; Onaca, Alexandru; Matei, Vasile; Cruceru, Nicolae; Pop, Olimpiu

doi:10.1016/j.geomorph.2017.07.029

Cited by 28 publications

(31 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The average slope inclination of the talus cones lies between 28° and 36° and thus within the range for such landforms (e.g. Pérez, 1989, Pérez, 1998, Francou and Manté, 1990, Jomelli and Francou, 2000, Sanders et al, 2009, Luckman, 2013b, Popescu et al, 2017, Volkwein et al, 2018. This can provide an indication of the dependence between rock material and slope 220 inclination of gravel or blocky material and thus supports the findings of other studies.…”

Section: Talus Cone Characteristicssupporting

confidence: 87%

“…5A) also points in a similar direction. The talus cone of PF follows a straight line over the entire length of the slope, whereas the other cones show a slight convexity in the upper and middle slope and a basal concavity at the end of the slope, which is in good 235 agreement with the works of Kotarba and Strömquist (1984), Luckman (2013b), and Popescu et al (2017). Nevertheless, it is very likely that the talus cone of the PF represents a pure talus cone and is reshaped since then by persistent rockfalls, whereas the talus cones of the other areas represent much older forms where different types of geomorphic processes occur.…”

Section: Talus Cone Characteristicssupporting

confidence: 83%

“…Jomelli and Francou (2000) state that longitudinal sorting of talus cones shows an increase of block sizes downslope. In their study, Popescu et al (2017) conclude that there is a gradual increase of boulder 280 https://doi.org/10.5194/nhess-2020-322 Preprint. Discussion started: 6 October 2020 c Author(s) 2020.…”

Section: Relationship Between Block Size Block Shape and Runout Lengmentioning

confidence: 96%

“…Some studies described the deposition of boulders on the talus cone as gravitational sorting, where larger blocks are deposited in the proximal part of the talus slope and smaller blocks at the upper part (e.g. Statham, 1973, Whitehouse and McSaveney, 1983, Kotarba and Strömquist, 1984, White, 1981, Jomelli and Francou, 2000, Sanders et al, 2009, Messenzehl and Dikau, 2017, Popescu et al, 2017, Kenner, 2019. The sorting of the blocks on the slope is a key factor for the roughness component of talus slopes and 65 https://doi.org/10.5194/nhess-2020-322 Preprint.…”

Section: Introduction 25mentioning

confidence: 99%

See 3 more Smart Citations

Assessing the effect of lithological setting, block characteristic and slope topography on the runout length of rockfalls in the Alps and on the La Réunion island

Wegner

Haas

Heckmann

et al. 2020

Preprint

View full text Add to dashboard Cite

Abstract. In high mountain regions, rockfalls are common processes, which transport different volumes of material and therefore endanger populated areas and infrastructure facilities. In four study areas within different lithological settings, LiDAR (light detection and ranging) data were acquired for a morphometric analysis of block sizes, block shapes and talus cone characteristics. Based on these high-resolution terrestrial laser scanning (TLS) data, the three axes of every block larger than 0.5 m in the referenced point cloud were measured. Block sizes and shapes are used to investigate them in the context of runout distances and to analyse the spatial distribution of blocks on the talus cone. We also investigate the influence of terrain parameters such as slope inclination, roughness and profile curvature (longitudinal profiles). Our study shows that the relation of block size within different lithological settings on runout length is complex, because we can neither confirm nor reject the theory of gravitational sorting. We also found that the block shape (axial ratio) does not have a simple influence on runout length, as it plays the role of a moderating parameter in two study sites (Gampenalm: GA, Dreitorspitze: DTS) while we could not confirm this for Piton de la Fournaise (PF) and Zwieselbach valley (ZBT). The derived roughness values show a clear difference between the four study sites. This also applies for the parameter of slope inclination and longitudinal profiles.

show abstract

Section: Talus Cone Characteristicssupporting

confidence: 87%

Section: Talus Cone Characteristicssupporting

confidence: 83%

Section: Relationship Between Block Size Block Shape and Runout Lengmentioning

confidence: 96%

Section: Introduction 25mentioning

confidence: 99%

See 2 more Smart Citations

Assessing the effect of lithological setting, block characteristic and slope topography on the runout length of rockfalls in the Alps and on the La Réunion island

Wegner

Haas

Heckmann

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…They become especially important in coarse blocky surface and subsurface material, which is abundant in mountainous regions. The role of air convection in the ground is also discussed in unfrozen soils (Weisbrod et al, 2009;Moore et al, 2011;Levintal et al, 2017), but ample field investigations have been done in a permafrost context in different regions (Harris and Pedersen, 1998;Kneisel et al, 2000;Delaloye et al, 2003;Sawada et al, 2003;Hanson and Hoelzle, 2004;Delaloye and Lambiel, 2005;Gubler et al, 2011;Morard et al, 2012;Schneider et al, 2012;Popescu et al, 2017). These studies clearly show that especially in coarse blocky material with a high permeability, convection has a significant influence on the ground thermal regime.…”

Section: Introductionmentioning

confidence: 99%

Air Convection in the Active Layer of Rock Glaciers

Wicky

Hauck

2020

Front. Earth Sci.

View full text Add to dashboard Cite

Coarse blocks are an abundant surface cover in mountainous permafrost landscapes. In this coarse blocky layer, air convection occurs and has a significant influence on the ground thermal regime of the underlying permafrost. Besides heat transfer through conduction, free convection of air takes place seasonally and leads to a pronounced ground cooling. Air convection has been observed and described in many field studies but is often neglected or parametrized in permafrost modeling. In the present study, air convection in the active layer of rock glaciers is explicitly modeled through a heat conduction equation coupled with Darcy's law over a two-dimensional geometry. With a series of numerical experiments, we show its effects on the thermal regime of the underlying permafrost. The ground permeability and the thermal gradient in the active layer are the most important parameters for air convection in the ground. On field sites with a high ground permeability (order of magnitude 10 −6 m 2), convection plays a crucial role and is required to correctly model measured borehole temperatures. The onset of natural convection occurs at critical Rayleigh numbers and is characterized by an increase of the standard deviation of the direction and the vorticity of the airflow field in the active layer. In the numerical solutions, the internal air circulation in the coarse blocky surface layer leads to an efficient ground cooling.

show abstract

An overcooled coarse‐grained talus slope at low elevation: New insights on air circulation and environmental impacts, Cannon Cliff, New Hampshire, USA

Germain,

Milot

2024

Earth Surf Processes Landf

View full text Add to dashboard Cite

Overcooled talus slopes are generally described as islands of sporadic permafrost below the lower alpine limit of permafrost. The negative thermal anomaly of the ground is mainly consecutive to the internal ventilation of the deposit, but it is also conditioned by multiple factors as topography, slope aspect and incline, openwork structure and coarseness of the deposit, air temperature, solar radiation and wind regime. Therefore, the study of the spatiotemporal dynamics of ventilation processes allows a better understanding of the phenomenon. At Cannon Cliff, New Hampshire (USA), several field visits and environmental monitoring allowed us to describe the varying nature and significance of the ventilation mechanisms that can be observed at the ground surface and associated with both the intensity and direction of the airflows in a talus debris accumulation/protalus rampart system. The thermal negative anomalies are strong enough to lower the ground temperature to the point of preserving ice during the late spring and summer seasons. The monitoring of the gradient between external (air) and internal (talus) temperatures coupled with several dendroecological and geomorphological analyses provided a complete environmental picture of the impacts, feedback and extent of the phenomenon.

show abstract

Low-altitude permafrost research in an overcooled talus slope–rock glacier system in the Romanian Carpathians (Detunata Goală, Apuseni Mountains)

Cited by 28 publications

References 28 publications

Assessing the effect of lithological setting, block characteristic and slope topography on the runout length of rockfalls in the Alps and on the La Réunion island

Assessing the effect of lithological setting, block characteristic and slope topography on the runout length of rockfalls in the Alps and on the La Réunion island

Air Convection in the Active Layer of Rock Glaciers

An overcooled coarse‐grained talus slope at low elevation: New insights on air circulation and environmental impacts, Cannon Cliff, New Hampshire, USA

Contact Info

Product

Resources

About