Sediment Transport and Bedrock Erosion by Wet Snow Avalanches in the Guggigraben, Matter Valley, Switzerland

Moore, Jeffrey R.; Egloff, J.; Nagelisen, Jan; Hunziker, Michael; Aerne, U.; Christen, Marc

doi:10.1657/1938-4246-45.3.350

Cited by 23 publications

(14 citation statements)

References 23 publications

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“…The area is known for its frequent and hazardous debris flow activity by historical and official records (kept since 1921; Hählen, ; Kober et al, ) and similarly evidenced by the numerous debris flow fans. Snow avalanches, common in steep alpine catchments occur frequently in the Guttannen region, however, their impact on sediment transfer is unknown for the region but has been reported to be substantial in other regions (Moore et al, ). Very large debris flow fans are formed in the less resistant schistose rocks around the Guttannen area (Figures and ), and belong to the Rotlaui and Spreitlaui torrents (area: ~5 km 2 each; Rickenmann and Koschni, ).…”

Section: Study Areamentioning

confidence: 99%

Postglacial to Holocene landscape evolution and process rates in steep alpine catchments

Kober

Hippe

Salcher

et al. 2018

Earth Surf Processes Landf

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Climate change and high magnitude mass wasting events pose adverse societal effects and hazards, especially in alpine regions. Quantification of such geomorphic processes and their rates is therefore critical but is often hampered by the lack of appropriate techniques and the various spatiotemporal scales involved in these studies. Here we exploit both in situ cosmogenic beryllium‐10 (10Be) and carbon‐14 (14C) nuclide concentrations for deducing exposure ages and tracing of sediment through small alpine debris flow catchments in central Switzerland. The sediment cascade and modern processes we track from the source areas, through debris flow torrents to their final export out into sink regions with cosmogenic nuclides over an unprecedented five‐year time series with seasonal resolution. Data from a seismic survey and a 90 m core revealed a glacially overdeepened basin, filled with glacial and paraglacial sediments. Surface exposure dating of fan boulders and radiocarbon ages constrain the valley fill from the last deglaciation until the Holocene and show that most of the fan existed in early Holocene times already. Current fan processes are controlled by episodic debris flow activity, snow (firn) and rock avalanches. Field investigations, digital elevation models (DEMs) of difference and geomorphic analysis agree with sediment fingerprinting with cosmogenic nuclides, highlighting that the bulk of material exported today at the outlet of the subcatchments derives from the lower fans. Cosmogenic nuclide concentrations steadily decrease from headwater sources to distal fan channels due to the incorporation of material with lower nuclide concentrations. Further downstream the admixture of sediment from catchments with less frequent debris flow activity can dilute the cosmogenic nuclide signals from debris flow dominated catchments but may also reach thresholds where buffering is limited. Consequently, careful assessment of boundary conditions and driving forces is required when apparent denudation rates derived from cosmogenic nuclide analysis are upscaled to larger regions. © 2018 John Wiley & Sons, Ltd.

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Section: Study Areamentioning

confidence: 99%

Postglacial to Holocene landscape evolution and process rates in steep alpine catchments

Kober

Hippe

Salcher

et al. 2018

Earth Surf Processes Landf

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“…Their ability to erode substrate and to incorporate and transport rock debris during runout can make them efficient agents of sediment mass transport, especially in steep mountain environments (e.g. Gardner 1970;Luckman 1977;Ackroyd 1986;Moore et al 2013). So-called 'dirty avalanches' (Rapp 1960) are regarded as most important snow avalanche type with respect to substrate erosion and sediment transport.…”

Section: Sediment Transport and Depositionmentioning

confidence: 99%

“…Snow avalanches are also considered to play an important role regarding sedimentary mass transfers (e.g. Caine 1976;Luckman 1977Luckman , 1978Bell et al 1990;Freppaz et al 2010;Confortola et al 2011;Moore et al 2013;Laute and Beylich 2014b), although reliable estimates in the context of the quantitative importance of snow avalanches within the sediment budget approach are still lacking, especially from extreme snow avalanche events.…”

Section: Introductionmentioning

confidence: 99%

Environmental Controls and Geomorphic Importance of a High‐Magnitude/Low‐Frequency Snow Avalanche Event in Bødalen, Nordfjord, Western Norway

Laute

Beylich

2014

Geografiska Annaler Series A

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Snow avalanches are common phenomena in western Norway. During the winter–spring period 2011/2012 an extreme snow avalanche occurred within the upper valley part of a steep and glacier‐connected mountain catchment (Bødalen) in western Norway. Compared with annually occurring regular snow avalanches, so‐called ‘extreme snow avalanche events’ are more difficult to monitor and to study as they are characterized by recurrence intervals often longer than a decade. Morphometric and meteorological controls of a high‐magnitude/low‐frequency snow avalanche event, its geomorphic effects as well as its related relative role in mass transport compared with the annually monitored snow avalanche activity within the Bødalen catchment were explored. Maximum values of snow height, velocity and pressure were predicted by applying a numerical run‐out simulation. The formation of this snow avalanche resulted from the combination of extraordinary meteorological conditions and a favourable morphometric setting of the source area. The snow avalanche path covered a total distance of 2900 m, including a stretch of 850 m where the snow avalanche slid downwards on top of the Bødalsbreen outlet glacier. Within the run‐out zone, directly located in front of the Bødalen outlet glacier, 2032 stones with b‐axes >5 cm were remobilized which corresponds to a total transferred debris mass of 460 t. Compared with annually occurring snow avalanches within the Bødalen drainage basin the relative importance of extreme‐sized snow avalanches is comparably low with respect to direct erosion and sediment transfer along rockwalls at higher slope areas. However, extreme‐sized snow avalanches play a significant role with respect to the remobilization of debris/sediment at lower slope areas as well as to down‐valley transport of sediment, including recognizable transfers of debris into the main stream channels of the drainage basin system whenever extreme snow avalanches reach the main channel.

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“…Furthermore, regional models are predicting an increase in wet avalanche activity for the coming decades, mostly related to an earlier occurrence in the spring season and an avalanche risk expected at higher altitude (Lazar and Williams, 2008;Castebrunet et al, 2014). In this study, we focus on the dense wet avalanches induced by entire snowpack destabilization; these avalanches glide on the substratum and are able to transport coarse detrital sediments such as gravels and pebbles (Luckman, 1977;Moore et al, 2013). Within 10 the last 40 years, snow cover duration has decreased, and the number of wet snow avalanches in the spring time is increasing (Valt and Paola, 2013;Ancey and Bain, 2015).…”

Section: Introductionmentioning

confidence: 99%

Wet avalanches: long-term evolution in the Western Alps under climate and human forcing

Fouinat¹,

Sabatier²,

David³

et al. 2018

Preprint

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Abstract. Understanding wet avalanche intensity and the role of past environmental changes on wet avalanche occurrence is a main concern especially in the context of a warming climate and accelerated environmental mutations. Avalanches are closely related to fast cryosphere changes and may cause major threats to human society. Here, we used the sedimentary 15 archive of the alpine Lake Lauvitel (western French Alps) to establish the first long-term avalanche record in this Alpine region. For this purpose, we used a novel CT scan methodology that allows the precise identification of coarse materialfrom sand to pebble -transported to the lake and embedded within the finer continuous sedimentation. We identified a total of 166 deposits over the last 3300 yrs cal. BP. In parallel, a detailed pollen analysis gave an independent record of environmental changes. Based on modern observation, lake monitoring, seismic investigations and sedimentological 20 evidences, coarse material deposits were attributed to wet avalanche events. Our results highlight the effect of vegetation cover on the avalanche hazard while a period of strong frequency increase occurred after 780 yrs cal. BP. In Lake Lauvitel, this period corresponds to a major forest clearance induced by the rise of human land-use. Climate forcing on the avalanche hazard was investigated before and after the vegetation shift. On a multi-centennial scale, wet avalanches preferably occur during periods of larger glacier extent, in which higher winter precipitations probably generate a sufficiently thick snow 25 cover. On a sub-centennial scale, avalanches are more frequent during periods of relative warming, resulting in a destabilisation of the same snow cover in spring season. Our results highlight as well the role of forest cover to mitigate wet snow avalanches occurrence. In the context of predicted warmer temperatures, this study raises the question of whether a wet avalanche hazard increase may be expected in the near future especially at higher altitudes.Clim. Past Discuss., https://doi

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Sediment Transport and Bedrock Erosion by Wet Snow Avalanches in the Guggigraben, Matter Valley, Switzerland

Cited by 23 publications

References 23 publications

Postglacial to Holocene landscape evolution and process rates in steep alpine catchments

Postglacial to Holocene landscape evolution and process rates in steep alpine catchments

Environmental Controls and Geomorphic Importance of a High‐Magnitude/Low‐Frequency Snow Avalanche Event in Bødalen, Nordfjord, Western Norway

Wet avalanches: long-term evolution in the Western Alps under climate and human forcing

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