scholarly journals Diatom diversity in headwaters influenced by permafrost thawing: First evidence from the Central Italian Alps

2018 ◽  
Vol 9 (2) ◽  
Author(s):  
Federica Rotta ◽  
Leonardo Cerasino ◽  
Anna Occhipinti-Ambrogi ◽  
Michela Rogora ◽  
Roberto Seppi ◽  
...  
Keyword(s):  
High Mountain ◽  
European Alps ◽  
Permafrost Degradation ◽  
Mountain Areas ◽  
Habitat Features ◽  
Glacier Ice ◽  
Water Ph ◽  
Thawing Rate ◽  
Permafrost Thawing ◽  
Alpine Hydrology

Glacier melting and permafrost thawing are the most evident effects of the current climate change that is strongly affecting high mountain areas, including the European Alps. As the thawing rate of subsurface ice is lower than for glacier ice, it is expected that, while glaciers retreat, an increasing number of Alpine headwaters will become more influenced by permafrost degradation during the 21st century. Despite the expected change in the relative importance of glacier and permafrost in determining Alpine hydrology, studies addressing effects of permafrost thawing on chemical and, especially, biological features of adjacent surface waters are still scarce. The present study contributes to characterise the epilithic and epiphytic diatom diversity in a set of permafrost-fed headwaters in three sub-catchments differing in bedrock lithology of the Italian Central Alps (Trentino Alto-Adige) in relation to water chemistry and habitat features. In addition, it explores chemical and biological differences between permafrost-fed streams and headwaters with no direct contact to permafrost, namely glacier-fed (kryal) and precipitation-/groundwater-fed (rhithral) streams. Permafrost-fed waters showed higher electrical conductivity and enhanced ion concentrations than glacier- and precipitation-fed waters, while concentration of trace elements (e.g. Sr, Ni, Zn, As) were more irregularly distributed among waters of different origin, though they showed a tendency to reach higher levels in permafrost-fed waters. Diatom species richness and diversity were lower in permafrost-fed headwaters, and were principally related to water pH and trace metal concentrations. Epiphytic diatom assemblages were more diverse than epilithic ones, independently from the water origin, while differences in species composition were not sufficient to unequivocally identify a typical diatom composition for the different water types considered in this study.

Using historical aerial imagery to assess multidecadal kinematics and elevation changes. Application to mountain permafrost in the French Alps.

2021 ◽  
Author(s):  
Diego Cusicanqui ◽  
Antoine Rabatel ◽  
Xavier Bodin ◽  
Christian Vincent ◽  
Emmanuel Thibert ◽  
...  
Keyword(s):  
Ice Core ◽  
Horizontal Displacement ◽  
Vertical Surface ◽  
Aerial Images ◽  
Surface Velocity ◽  
High Mountain ◽  
European Alps ◽  
Permafrost Degradation ◽  
Mountain Areas ◽  
Mountain Permafrost

<p>Glacial and periglacial environments are highly sensitive to climate change, even more in mountain areas where warming is faster and, as a consequence, perennial features of the cryosphere like glaciers and permafrost have been fast evolving in the last decades. In the European Alps, glaciers retreat and permafrost thawing have led to the destabilization of mountain slopes, threatening human infrastructures and inhabitants. The observation of such changes at decadal scales is often limited to sparse in situ observations.</p><p>Here, we present three study cases of mountain permafrost sites based on a multidisciplinary approach over almost seven decades. The goal is to investigate and quantify morphodynamic changes and understand the causes of these evolutions. We used stereo-photogrammetry techniques to generate orthophotos and (DEMs) from historical aerial images (available, in France since 1940s). From this, we produced diachronic comparison of DEMs to quantify vertical surface changes, as well as feature tracking techniques of multi-temporal digital orthophotos for estimating horizontal displacement rates. Locally, high-resolution datasets (i.e. LiDAR surveys, UAV acquisitions and Pléiades stereo imagery) were also exploited to improve the quality of photogrammetric products. In addition, we combine these results with geophysics (ERT and GPR) to estimate the ice content, geomorphological surveys to describe the complex environments and the relationship with climatic forcing.</p><p>The first study case is the Laurichard rock glacier, where we were able to quantify changes of emergence velocities, fluxes, and volume. Together with an acceleration of surface velocity, important surface lowering have been found over the period 1952-2019, with a striking spatiotemporal reversal of volume balance.</p><p>The second study site is the Tignes glacial and periglacial complex, where the changes of thermokarstic lakes surface were quantified. The results suggest that drainage probably affects the presence and the evolution of the largest thermorkarst. Here too, a significant ice loss was found on the central channel concomitant to an increase in surface velocities.</p><p>The third study site is the Chauvet glacial and periglacial complex where several historical outburst floods are recorded during the 20th century, likely related to the permafrost degradation, the presence of thermokarstic lakes, and an intra-glacial channel. The lateral convergence of ice flow, due to the terrain subsidence caused by the intense melting, may cause the closure of the channel with a subsequent refill of the thermokarstic depression and finally a new catastrophic event.</p><p>Our results highlight the important value of historical aerial photography for having a longer perspective on the evolution of the high mountain cryosphere, thanks to accurate quantification of pluri-annual changes of volume and surface velocity. For instance, we could evidence : (1) a speed-up of the horizontal displacements since the 1990s in comparison with the previous decades; (2) an important surface lowering related to various melting processes (ice-core, thermokarst) for the three study sites; (3) relationships between the observed evolution and the contemporaneous climate warming, with a long-term evolution controlled by the warming of the ground and short-term changes that may relate to snow or precipitation or to the activity of the glacial-periglacial landforms.</p>

scholarly journals On the influence of topographic, geological and cryospheric factors on rock avalanches and rockfalls in high-mountain areas

2012 ◽  
Vol 12 (1) ◽  
pp. 241-254 ◽  
Author(s):  
L. Fischer ◽  
R. S. Purves ◽  
C. Huggel ◽  
J. Noetzli ◽  
W. Haeberli
Keyword(s):  
Slope Failure ◽  
Temporal Distribution ◽  
High Mountain ◽  
European Alps ◽  
Permafrost Degradation ◽  
Slope Failures ◽  
Mountain Areas ◽  
Investigation Area ◽  
Rock Avalanches ◽  
Slope Instabilities

Abstract. The ongoing debate about the effects of changes in the high-mountain cryosphere on rockfalls and rock avalanches suggests a need for more knowledge about characteristics and distribution of recent rock-slope instabilities. This paper investigates 56 sites with slope failures between 1900 and 2007 in the central European Alps with respect to their geological and topographical settings and zones of possible permafrost degradation and glacial recession. Analyses of the temporal distribution show an increase in frequency within the last decades. A large proportion of the slope failures (60%) originated from a relatively small area above 3000 m a.s.l. (i.e. 10% of the entire investigation area). This increased proportion of detachment zones above 3000 m a.s.l. is postulated to be a result of a combination of factors, namely a larger proportion of high slope angles, high periglacial weathering due to recent glacier retreat (almost half of the slope failures having occurred in areas with recent deglaciation), and widespread permafrost occurrence. The lithological setting appears to influence volume rather than frequency of a slope failure. However, our analyses show that not only the changes in cryosphere, but also other factors which remain constant over long periods play an important role in slope failures.

Is Evaporation an Important Component in High Alpine Hydrology?

1981 ◽  
Vol 12 (4-5) ◽  
pp. 217-224 ◽  
Author(s):  
Herbert Lang
Keyword(s):  
Water Balance ◽  
Sensible Heat Flux ◽  
Heat Fluxes ◽  
High Mountain ◽  
European Alps ◽  
Mountain Areas ◽  
Secondary Importance ◽  
Annual Evaporation ◽  
High Specific Energy ◽  
Alpine Hydrology

The knowledge of evaporation in the high mountain areas of the European Alps is still rather poor. It is generally regarded as a component of secondary importance in the water balance. The available mean areal evaporation data are based on conventional water balance estimations and suffer from inaccuracies in the determination of precipitation. This is also obvious from the rate of decrease in mean annual evaporation with altitude indicated by different authors; these values range from 71 mm to 356 mm pro 1,000 m of altitude. From heat balance studies on glaciers it is evident that evaporation/condensation as a process of high specific energy exchange can be a determinative factor in the shortterm variations of melt rates. The scale width of the daily latent heat fluxes reaches at magnitudes equal to or larger than those of net radiation and sensible heat flux.

Comparing streamflow analysis and remote sensing observations to assess climate change impact on permafrost degradation

2020 ◽  
Author(s):  
flore sergeant ◽  
rene therrien ◽  
ludovic oudin ◽  
anne jost ◽  
françois anctil
Keyword(s):  
Climate Change ◽  
Remote Sensing ◽  
Satellite Images ◽  
Ground Subsidence ◽  
Permafrost Degradation ◽  
Analysis Method ◽  
Temporal And Spatial ◽  
Thawing Rate ◽  
Permafrost Thawing

<p><strong>ABSTRACT</strong></p><p>Due to polar amplification of climate change, high latitudes are warming up twice as fast as the rest of the world. This warming leads to permafrost thawing, which induces greenhouse gases release, ground subsidence, and modifies surface and subsurface hydrologic regimes. Ground subsidence in turn affects local infrastructure stability. In this context and to better manage future infrastructures and water resources of northern regions, it is crucial to be able to evaluate the thawing rate of permafrost.</p><p>In many Arctic zones, the frequency of environmental disturbances caused by permafrost thawing increases so rapidly that maintaining an accurate inventory of the state of permafrost at a regional scale represents a great challenge. Moreover, depending on the study area and the permafrost ice content, the thawing rate can vary from millimetres to decimeters per year. Another current challenge is the limited availability of temporal and spatial data on permafrost thawing rates.</p><p>To address the above challenges, two indirect methods are used: (1) Arctic river streamflow analysis method and (2) Ground settlement analysis method via satellite image observation. Both methods use free-access data that have an exceptionally large temporal and spatial coverage capacity for such a poorly instrumented region. The first method analyses the recession events’ behavior of Arctic streams and relates those behaviors to changes in catchment-scale depth to permafrost that influences storage-discharge dynamics. This work differs from previous hydrological system analysis in northern systems in that it looks at long-term trends (>10 years) in recession intercept to assess permafrost dynamics, while other studies looked at recession characteristics within a season to assess active-layer dynamics. The second method analyses satellite images of the Arctic ground and associates surface elevation change to long-term permafrost degradation due to climate change.</p><p>Both methods have already been tested through multiple local investigations and gave promising results. The recession flow analysis method has been applied to Yukon river basin, northern Sweden basins and Lena basin in Siberia, while the remote sensing analysis method has been tested on Baffin Island, Herschel Island in Canada, North Slope of Alaska and the Tibetan Plateau. However, no comparative study and no large-scale application have been conducted so far. Extending the analysis to hundreds of Arctic basins and comparing the resulting permafrost-thawing rate values from both methods constitute the innovative aspect of this project.</p><p> </p><p>KEY WORDS: climate change, permafrost thawing, storage-discharge dynamics, ground subsidence, satellite images</p>

scholarly journals LOCAL AND GENERAL MONITORING OF FORNI GLACIER (ITALIAN ALPS) USING MULTI-PLATFORM STRUCTURE-FROM-MOTION PHOTOGRAMMETRY

2017 ◽  
Vol XLII-2/W7 ◽  
pp. 1547-1554 ◽  
Author(s):  
M. Scaioni ◽  
M. Corti ◽  
G. Diolaiuti ◽  
D. Fugazza ◽  
M. Cernuschi
Keyword(s):  
Structure From Motion ◽  
Accuracy Assessment ◽  
Laser Scanner ◽  
High Mountain ◽  
Italian Alps ◽  
Mountain Areas ◽  
Medium Resolution ◽  
Stereo Photogrammetry ◽  
Glacier Ice ◽  
Global And Local

Experts from the University of Milan have been investigating Forni Glacier in the Italian alps for decades, resulting in the archive of a cumbersome mass of observed data. While the analysis of archive maps, medium resolution satellite images and DEM’s may provide an overview of the long-term processes, the application of close-range sensing techniques offers the unprecedented opportunity to operate a 4D reconstruction of the glacier geometry at both global and local levels. In the latest years the availability of high-resolution DEM's from stereo-photogrammetry (2007) and UAV-photogrammetry (2014 and 2016) has allowed an improved analysis of the glacier ice-mass balance within time. During summer 2016 a methodology to record the local disruption processes has been investigated. The presence of vertical and sub-vertical surfaces has motivated the use of Structure-from-Motion Photogrammetry from ground-based stations, which yielded results comparable to the ones achieved using a long-range terrestrial laser scanner. This technique may be assumed as benchmarking for accuracy assessment, but is more difficult to be operated in high-mountain areas. Nevertheless, the measurement of GCP’s for the terrestrial photogrammetric project has revealed to be a complex task, involving the need of a total station a GNSS. The effect of network geometry on the final output has also been investigated for SfM-Photogrammetry, considering the severe limitations implied in the Alpine environment.

scholarly journals Effects of free-flight activities on wildlife: a poorly understood issue in conservation

2021 ◽  
pp. 1-9
Author(s):  
Jorge Tobajas ◽  
Francisco Guil ◽  
Antoni Margalida
Keyword(s):  
Roe Deer ◽  
High Mountain ◽  
Feeding Time ◽  
European Alps ◽  
Free Flight ◽  
Negative Effects ◽  
Mountain Areas ◽  
Bearded Vulture ◽  
Cinereous Vulture ◽  
The Impact

Summary Recreational activities may have negative effects on wildlife, but there are very few studies specifically on the effects of free-flight activities (i.e., hang-gliders, paragliders and their powered derivatives) on wildlife. We review the existing scientific studies on this issue in order to identify the gaps in knowledge at the taxonomic-group level in order to develop guidelines to minimize the impacts of recreational free-flight on wildlife. We found that studies mainly concerned the effects on four ungulate species (chamois, red deer, roe deer and Alpine ibex) and, to a lesser extent, on raptors such as the golden eagle and two vulture species (bearded vulture and cinereous vulture). The studies have generally been carried out in high mountain areas (e.g., the European Alps). Data show that free-flight activities create disturbances and have negative effects on wildlife, resulting in increased energy expenditure, reduction of feeding time, abandonment of feeding areas, reduced breeding output, loss of body condition, increased predation risk and harm from flight accidents. However, the lack of studies on many species and areas, along with the small number of long-term studies, prevents proper assessment of the current situation regarding the impact of this activity on wildlife. We provide recommendations to improve the regulation of this activity.

A high-resolution multi-phase thermo-geophysical permafrost rock model to verify long-term ERT monitoring at the Zugspitze (German/Austrian Alps)

2021 ◽  
Author(s):  
Tanja Schroeder ◽  
Michael Krautblatter
Keyword(s):  
Electrical Resistivity ◽  
Energy Balance ◽  
Thermal Regime ◽  
Thermal Evolution ◽  
High Mountain ◽  
Permafrost Degradation ◽  
Complex Topography ◽  
Mountain Areas ◽  
Permafrost Rock

<div> <p><span>In the context of climate change, permafrost degradation is a key variable in understanding rock slope failures in high mountain areas. Permafrost degradation imposes a variety of environmental, economic and humanitarian impacts on infrastructure and people in high mountain areas. Therefore, new high-quality monitoring and modelling strategies are needed.</span></p> </div><div> <p><span>We developed a new, numerical, thermo-geophysical rock permafrost model (TGRPM) to assess spatial-temporal variations of the ground thermal regime in steep permafrost rock walls on the basis of 13-years of Electrical Resistivity Tomography (ERT) monitoring of permafrost at the Zugspitze. TGRPM is a simple to understand and workable numerical 2D MATLAB-model, which is adaptable to different topographic and sub-surface conditions, and further relies on a minimum of input-data to assess the surface energy balance and the ground thermal regime. It simulates the thermal response for permafrost rock walls, including their complex topography, to climate forcing over multiple years. It aims to assess seasonal and long-term permafrost development in steep alpine rock walls, as well as serving as a straightforward calculation routine, which is solely based on physical processes and does not require any fitting of certain parameters. </span></p> </div><div> <p><span>At first, the model was tested against direct temperature measurements from the LfU-borehole at the Zugspitze summit to prove its accuracy. Then, it is run against a 13-year ERT data-set from the Zugspitze Kammstollen to validate the ERT measurements.</span></p> </div><div> <p><span>Here, we show the first thermo-geophysical model referencing thermal evolution in a permafrost rock wall with temperature-calibrated ERT. The TGRPM successfully computes the thermal evolution within the Zugspitze mountain ridge from a 2D coupled energy balance and heat conduction scheme in complex topography. It furthermore validates the temperature-resistivity relationship by Krautblatter et al. (2010) for natural rock walls reaching a correlation of 85 to 95 % between measured, ERT-derived and modelled temperatures.</span></p> </div><div><span>Krautblatter, M., Verleysdonk, S., Flores-Orozco, A. & Kemna, A. (2010): Temperature-calibrated imaging of seasonal changes in permafrost rock walls by quantitative electrical resistivity </span><span>tomography </span>(Zugspitze, German/Austrian Alps). <em>J. Geophys. Res. </em>115: F02003.</div>

scholarly journals Analysis of microseismic signals and temperature recordings for rock slope stability investigations in high mountain areas

2012 ◽  
Vol 12 (7) ◽  
pp. 2283-2298 ◽  
Author(s):  
C. Occhiena ◽  
V. Coviello ◽  
M. Arattano ◽  
M. Chiarle ◽  
U. Morra di Cella ◽  
...  
Keyword(s):  
Rock Mass ◽  
Monitoring System ◽  
Temporal Distribution ◽  
Rock Slope Stability ◽  
High Mountain ◽  
Permafrost Degradation ◽  
Rock Falls ◽  
Mountain Areas ◽  
Microseismic Activity ◽  
Set Up

Abstract. The permafrost degradation is a probable cause for the increase of rock instabilities and rock falls observed in recent years in high mountain areas, particularly in the Alpine region. The phenomenon causes the thaw of the ice filling rock discontinuities; the water deriving from it subsequently freezes again inducing stresses in the rock mass that may lead, in the long term, to rock falls. To investigate these processes, a monitoring system composed by geophones and thermometers was installed in 2007 at the Carrel hut (3829 m a.s.l., Matterhorn, NW Alps). In 2010, in the framework of the Interreg 2007–2013 Alcotra project no. 56 MASSA, the monitoring system has been empowered and renovated in order to meet project needs. In this paper, the data recorded by this renewed system between 6 October 2010 and 5 October 2011 are presented and 329 selected microseismic events are analysed. The data processing has concerned the classification of the recorded signals, the analysis of their distribution in time and the identification of the most important trace characteristics in time and frequency domain. The interpretation of the results has evidenced a possible correlation between the temperature trend and the event occurrence. The research is still in progress and the data recording and interpretation are planned for a longer period to better investigate the spatial-temporal distribution of microseismic activity in the rock mass, with specific attention to the relation of microseismic activity with temperatures. The overall goal is to verify the possibility to set up an effective monitoring system for investigating the stability of a rock mass under permafrost conditions, in order to supply the researchers with useful data to better understand the relationship between temperature and rock mass stability and, possibly, the technicians with a valid tool for decision-making.

New multi-phase thermo-geophysical model: Validate ERT-monitoring & assess permafrost evolution in alpine rock walls (Zugspitze, German/Austrian Alps)

2020 ◽  
Author(s):  
Tanja Schroeder ◽  
Riccardo Scandroglio ◽  
Verena Stammberger ◽  
Maximilian Wittmann ◽  
Michael Krautblatter
Keyword(s):  
Electrical Resistivity ◽  
Heat Fluxes ◽  
High Mountain ◽  
Permafrost Degradation ◽  
Mountain Areas ◽  
Rock Wall ◽  
Permafrost Rock ◽  
Geophysical Model ◽  
Multi Phase

<p><span>In the context of climate change, permafrost degradation is a key variable in understanding rock slope failures in high mountain areas. Permafrost degradation imposes a variety of environmental, economic and humanitarian impacts on infrastructure and people in high mountain areas. Therefore, new high-quality monitoring and modelling strategies are needed.</span></p><p><span>Electrical Resistivity Tomography (ERT) is the predominant permafrost monitoring technique in high mountain areas. Its high temperature sensitivity for frozen vs. unfrozen conditions, combined with the resistivity-temperature laboratory calibration on Wettersteinkalk (Zugspitze) (Krautblatter et al. 2010) gives us quantitative information on site-specific rock wall temperatures (Magnin <em>et al.</em> 2015). Long-term ERT-Measurements (2007/2014 – now) were taken at the Kammstollen along the northern Zugspitze rock face. Two high-resistivity bodies along the investigation area reach resistivity values ≥10<sup>4.5</sup></span>Ω<span>m (</span><span>∼</span><span>−0.5 </span><span>°</span><span>C), indicating frozen rock, displaying a core section with resistivities ≥10<sup>4.7</sup></span>Ω<span>m (</span><span>∼</span><span>−2 </span><span>°</span><span>C) (Krautblatter <em>et al.</em>, 2010). We can differentiate seasonal variability, seen by laterally aggrading and degrading marginal sections (Krautblatter <em>et al.</em>, 2010) and singular effects due to environmental factors and extreme weather events.</span></p><p><span>Here, we present a new local high-resolution numerical, process-orientated thermo-geophysical model (TGM) for steep permafrost rock walls. The model links apparent resistivities, the ground thermal regime and meteorological forcings as seasonality and long-term climate change to validate the ERT and project future conditions. The TGM comprises a surface energy balance model, conductive energy transport, turbulent and seasonal heat fluxes (sensible, latent, melt and rain heat fluxes) including phase-change, as well as a multi-phase rock wall composition.</span></p><p><span>Finally, we can reproduce the natural temperature field in the rock wall, assess the spatial-temporal permafrost evolution in alpine rock walls, validate the ERT measurements via the new TGM and the applicability of the laboratory derived resistivity-temperature relationship by Krautblatter et al. (2010) for natural rock-wall conditions.</span></p><p><span> </span></p><p><span>Krautblatter, M., Verleysdonk, S., Flores-Orozco, A. & Kemna, A. (2010): Temperature- calibrated imaging of seasonal changes in permafrost rock walls by quantitative electrical resistivity </span><span>tomography</span><span> (Zugspitze, German/Austrian Alps). <em>J. Geophys. Res. </em>115: F02003.</span></p><p><span>Magnin, F., Krautblatter, M., Deline, P., Ravanel, L., Malet, E., Bevington, A. (2015): Determination of warm, sensitive permafrost areas in near-vertical rockwalls and evaluation of distributed models by electrical resistivity tomography. <em>J. Geophys. Res. Earth Surf.</em>, 120, 745-762.</span></p>

Debris flows originating in the mountain cryosphere under a changing climate: A review

2020 ◽  
pp. 030913332096170
Author(s):  
Guo-An Yu ◽  
Weiwei Yao ◽  
He Qing Huang ◽  
Zhaofei Liu
Keyword(s):  
Formation Mechanism ◽  
Debris Flows ◽  
Global Climate ◽  
Rock Joints ◽  
Future Research ◽  
High Mountain ◽  
Permafrost Degradation ◽  
Mountain Areas ◽  
Changing Climate ◽  
Triggering Conditions

Debris flows originating in the mountain cryosphere (DFMC) are one of the most globally important, widely distributed mass flows (and natural geohazards) in mountain areas with a high altitude and/or high latitude. This is particularly the case in high mountain areas that have been undergoing rapid glacier retreat, permafrost degradation, and other melt/thaw related processes. As a consequence, the actual hazards and potential risks of DFMC have drawn increasing attention in the context of global climate change (i.e. a rising temperature and higher occurrence of strong precipitation events). Unlike debris flows at low elevations, where their occurrence is closely related to precipitation (intensity and duration), the breach of a DFMC event depends on precipitation and/or air temperature, which in turn influence melt/thaw processes, rending the formation mechanism much more complicated. Although research has been widely carried out on DFMC in past decades, there is still a long way to go before we have reached a complete understanding of the formation mechanism and triggering conditions. This review summarizes recent progress in the study of DFMC, including typical DFMC events and their causes, the failure mechanisms of rock (or ice-rock joints), the characteristics of moraine deposits, initiation through hydraulic erosion (entrainment), the relationship between DFMC initiation and meteorological conditions, and the slope stability of the mountain cryosphere under a changing climate. Several issues that should be addressed in future research are also discussed.

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