scholarly journals The Multetta Debris Fan, Eastern Swiss Alps: A 500-Year Debris Flow Chronology

1999 ◽  
Vol 31 (2) ◽  
pp. 128 ◽  
Author(s):  
F. Baumann ◽  
K. F. Kaiser
Keyword(s):  
Debris Flow ◽  
Swiss Alps

scholarly journals The importance of entrainment and bulking on debris flow runout modeling: examples from the Swiss Alps

2015 ◽  
Vol 15 (11) ◽  
pp. 2569-2583 ◽  
Author(s):  
F. Frank ◽  
B. W. McArdell ◽  
C. Huggel ◽  
A. Vieli
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Field Data ◽  
Average Rate ◽  
Hazard Analysis ◽  
Maximum Shear Stress ◽  
Empirical Relationship ◽  
Swiss Alps ◽  
Field Site ◽  
Practical Applications

Abstract. This study describes an investigation of channel-bed entrainment of sediment by debris flows. An entrainment model, developed using field data from debris flows at the Illgraben catchment, Switzerland, was incorporated into the existing RAMMS debris-flow model, which solves the 2-D shallow-water equations for granular flows. In the entrainment model, an empirical relationship between maximum shear stress and measured erosion is used to determine the maximum potential erosion depth. Additionally, the average rate of erosion, measured at the same field site, is used to constrain the erosion rate. The model predicts plausible erosion values in comparison with field data from highly erosive debris flow events at the Spreitgraben torrent channel, Switzerland in 2010, without any adjustment to the coefficients in the entrainment model. We find that by including bulking due to entrainment (e.g., by channel erosion) in runout models a more realistic flow pattern is produced than in simulations where entrainment is not included. In detail, simulations without entrainment show more lateral outflow from the channel where it has not been observed in the field. Therefore the entrainment model may be especially useful for practical applications such as hazard analysis and mapping, as well as scientific case studies of erosive debris flows.

Changing debris flow activity after sudden sediment input: a case study from the Swiss Alps

Geology Today ◽  
2017 ◽  
Vol 33 (6) ◽  
pp. 216-223 ◽  
Author(s):  
Patrick Baer ◽  
Christian Huggel ◽  
Brian W. McArdell ◽  
Florian Frank
Keyword(s):  
Debris Flow ◽  
Swiss Alps ◽  
Sediment Input ◽  
Flow Activity

scholarly journals Atmospheric Forcing of Debris Flows in the Southern Swiss Alps

2013 ◽  
Vol 52 (7) ◽  
pp. 1554-1560 ◽  
Author(s):  
Andrea Toreti ◽  
Michelle Schneuwly-Bollschweiler ◽  
Markus Stoffel ◽  
Jürg Luterbacher
Keyword(s):  
Time Series ◽  
Debris Flow ◽  
Debris Flows ◽  
Large Scale ◽  
Reanalysis Data ◽  
Swiss Alps ◽  
Classification Algorithms ◽  
Precipitation Series ◽  
Large Scale Circulation

AbstractThis article addresses the role of large-scale circulation and thermodynamical features in the release of past debris flows in the Swiss Alps by using classification algorithms, potential instability, and convective time scale. The study is based on a uniquely dense dendrogeomorphic time series of debris flows covering the period 1872–2008, reanalysis data, instrumental time series, and gridded hourly precipitation series (1992–2006) over the area. Results highlight the crucial role of synoptic and mesoscale forcing as well as of convective equilibrium on triggering rainfalls. Two midtropospheric synoptic patterns favor anomalous southwesterly flow toward the area and high potential instability. These findings imply a certain degree of predictability of debris-flow events and can therefore be used to improve existing alert systems.

scholarly journals The importance of erosion for debris flow runout modelling from applications to the Swiss Alps

2015 ◽  
Vol 3 (4) ◽  
pp. 2379-2417 ◽  
Author(s):  
F. Frank ◽  
B. W. McArdell ◽  
C. Huggel ◽  
A. Vieli
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Field Data ◽  
Hazard Analysis ◽  
Maximum Shear Stress ◽  
Swiss Alps ◽  
Erosion Model ◽  
Practical Applications ◽  
Bed Erosion ◽  
The Relationship

Abstract. This study describes an investigation of channel-bed erosion of sediment by debris flows. An erosion model, developed using field data from debris flows at the Illgraben catchment, Switzerland, was incorporated into the existing RAMMS debris-flow model, which solves the 2-D shallow-water equations for granular flows. In the erosion model, the relationship between maximum shear stress and measured erosion is used to determine the maximum potential erosion depth. Additionally, the maximum rate of erosion, measured at the same field site, is used to constrain the erosion rate. The model predicts plausible erosion values in comparison with field data from highly erosive debris flow events at the Spreitgraben torrent channel, Switzerland in 2010, without any adjustment to the coefficients in the erosion model. We find that by including channel erosion in runout models a more realistic flow pattern is produced than in simulations where entrainment is not included. In detail, simulations without channel bed erosion show more lateral outflow from the channel where it has not been observed in the field. Therefore the erosion model may be especially useful for practical applications such as hazard analysis and mapping, as well as scientific case studies of erosive debris flows.

scholarly journals Unraveling the patterns of late Holocene debris-flow activity on a cone in the Swiss Alps: Chronology, environment and implications for the future

2008 ◽  
Vol 60 (3-4) ◽  
pp. 222-234 ◽  
Author(s):  
Markus Stoffel ◽  
Delphine Conus ◽  
Michael A. Grichting ◽  
Igor Lièvre ◽  
Gilles Maître
Keyword(s):  
Debris Flow ◽  
Late Holocene ◽  
Swiss Alps ◽  
The Future ◽  
Flow Activity

scholarly journals Recent geomorphic destabilization of mountain slopes, a possible link to climate change? Two case studies from Switzerland

2020 ◽  
Author(s):  
Hanne Hendrickx ◽  
Reynald Delaloye ◽  
Jan Nyssen ◽  
Amaury Frankl
Keyword(s):  
Climate Change ◽  
Debris Flow ◽  
Mass Movement ◽  
Swiss Alps ◽  
Aerial Photographs ◽  
High Mountain ◽  
Permafrost Degradation ◽  
Rock Wall ◽  
Rock Face ◽  
Talus Slope

<p>Geomorphological destabilisations in high mountain areas are often linked to permafrost degradation and changing precipitation intensities, induced by climate change. Considering the complex interaction between meteorological conditions, geology and topography, two alpine mass movements that took place in 2019 in the canton of Valais (Swiss Alps) were investigated with regard to their possible causes. During three consecutive summers (2017-2019), independent surveys were carried out on a high alpine talus slope at Col du Sanetsch (2100 – 2750 m a.s.l.) and an unstable rock face at Grosse Grabe, Mattertal (2600 – 2700 m a.s.l.), using unmanned aerial vehicle (UAV) and terrestrial laser scanning (TLS). The resulting high-resolution topography allows detecting and quantifying small and large geomorphic changes, such as rock tilting, rockfalls, rockslides, erosion and depositions of rock debris by snow avalanche action, debris channel cutting and fill and debris flow deposits. In both study areas, the summer of 2019 was characterized by mass movement events of greater magnitude than the geomorphic activity measured in the summers before.</p><p>At Grosse Grabe, the rock face was observed by webcam imagery since 2011, in the background of a rock glacier, which was initially the main object of survey. Isolated rock falls started in January 2017, launching a more accurate survey of the rock face by TLS in July 2017. In the next two summers, the entire unstable part of the rock wall, 70 m high, had been tilting at an increasing rate (1 to 3.3 cm/month). From mid-July until the end of October 2019, consecutive large rock fall events (up to > 10,000 m<sup>3</sup>) lead to the complete collapse of the monitored rock face (5000 m<sup>2</sup>), with a total volume of more than 60,000 m<sup>3</sup>. After the collapse of this heavily fractured, south facing rock face, the long-lasting wet rockfall scar indicated the presence of thawing permafrost ice. Beside the geological characteristics, which are favouring the rock wall instability, the consequences of the multi-decennial significant warming of the permafrost is presumably an implicated factor.</p><p>On the talus slope (2 km<sup>2</sup>) that was surveyed at Col du Sanetsch, a large debris flow event (ca. 20,000 m<sup>3</sup> spread over multiple debris flow channels) was observed in the evening of 11 August 2019. Most of the mobilized sediments originated from incision of the talus apex area, while only a small part came from intermediate debris storage within rock wall gullies. An analysis of historical aerial photographs shows that the total displaced volume during the 2019 event exceeds each historical debris flow event that occurred on the talus slope since 1946.</p><p>In contrast to Grosse Grabe, where weather conditions have played no role on the development of the instability, the debris flow event at Col de Sanetsch is linked to an intense prefrontal supercell, causing rainfall intensities between 10 and 25 mm/h, in some places in less than 15 minutes. As such events are presumed to become more frequent with climate change, more debris flow events of this type can be expected in the future.</p>

scholarly journals Possible impacts of climate change on debris-flow activity in the Swiss Alps

2013 ◽  
Vol 122 (1-2) ◽  
pp. 141-155 ◽  
Author(s):  
Markus Stoffel ◽  
Thomas Mendlik ◽  
Michelle Schneuwly-Bollschweiler ◽  
Andreas Gobiet
Keyword(s):  
Climate Change ◽  
Debris Flow ◽  
Swiss Alps ◽  
Flow Activity ◽  
Impacts Of Climate Change

Recent Evolution of Debris-Flow Fans in the Central Swiss ALPS and Associated Risk Assessment: Two Examples in Roseg Valley

2009 ◽  
Vol 30 (2) ◽  
pp. 105-129 ◽  
Author(s):  
Valentina Garavaglia ◽  
Manuela Pelfini ◽  
Alfredo Bini ◽  
Luca Arzuffi ◽  
Mauro Bozzoni
Keyword(s):  
Risk Assessment ◽  
Debris Flow ◽  
Swiss Alps

scholarly journals Regional-scale GIS-models for assessment of hazards from glacier lake outbursts: evaluation and application in the Swiss Alps

2003 ◽  
Vol 3 (6) ◽  
pp. 647-662 ◽  
Author(s):  
C. Huggel ◽  
A. Kääb ◽  
W. Haeberli ◽  
B. Krummenacher
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Flow Direction ◽  
Regional Scale ◽  
Satellite Image ◽  
Swiss Alps ◽  
Special Focus ◽  
High Mountain ◽  
Mountain Areas ◽  
Single Flow

Abstract. Debris flows triggered by glacier lake outbursts have repeatedly caused disasters in various high-mountain regions of the world. Accelerated change of glacial and periglacial environments due to atmospheric warming and increased anthropogenic development in most of these areas raise the need for an adequate hazard assessment and corresponding modelling. The purpose of this paper is to pro-vide a modelling approach which takes into account the current evolution of the glacial environment and satisfies a robust first-order assessment of hazards from glacier-lake outbursts. Two topography-based GIS-models simulating debris flows related to outbursts from glacier lakes are presented and applied for two lake outburst events in the southern Swiss Alps. The models are based on information about glacier lakes derived from remote sensing data, and on digital elevation models (DEM). Hydrological flow routing is used to simulate the debris flow resulting from the lake outburst. Thereby, a multiple- and a single-flow-direction approach are applied. Debris-flow propagation is given in probability-related values indicating the hazard potential of a certain location. The debris flow runout distance is calculated on the basis of empirical data on average slope trajectory. The results show that the multiple-flow-direction approach generally yields a more detailed propagation. The single-flow-direction approach, however, is more robust against DEM artifacts and, hence, more suited for process automation. The model is tested with three differently generated DEMs (including aero-photogrammetry- and satellite image-derived). Potential application of the respective DEMs is discussed with a special focus on satellite-derived DEMs for use in remote high-mountain areas.

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