DREVENEUSE (VS)

Cold scree slopes, relict rock glaciers

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Elevation: 1450-1800m  -   Massif: Chablais Prealps   -   Commune: Collombey-Muraz (VS)  

This mid-altitude site has been explored since 2003. It includes a multitude of scree slopes distributed over various orientations. The presence of permafrost, whose existence is owed to a complex ventilation system, was assumed. Two drillings (5 et 15 m depth), carried out in November of 2004 in the mid- and lower sections of one scree slope located in Dreveneuse d’En Bas, confirmed the sporadic presence of permafrost. This permafrost occurrence is directly linked to the cooling in winter caused by the ventilation mechanism. The internal air flow direction inside the scree slopes is reversible. In Dreveneuse d’En Bas it flows downwards while air temperature remains above approximately +4 °C and upwards in the reverse case. As a result, lower sections stay constantly cold, thus allowing snow to persist longer. Conversely, the ground is never freezing in the upper sections of the scree slope and snow disappears very early. The vegetation is adapted to the different thermal regimes of the underground. The same applies to scree slopes and relict rock glaciers situated in higher sections of the valley, where the temperature threshold for the inversion decreases with altitude. This field site is part of the “Temperature” section of the Swiss permafrost monitoring network (PERMOS).

 

  • Measurements and observations

    Thermal (ground surface temperature: GST, BTS; temperature in boreholes)
    Geophysics (permanent electrical resistivity system installed in 2008, refraction seismic)
    Weather station since 2014

  • Figures

    Daily sub-surface temperature of the Dreveneuse d'En Bas talus slope. Dr-10 (1570 m a.s.l.) and Dr-11 (1575 m a.s.l.) are located in the lower section of the talus slope, Dr-14 in the uppermost part (1595 m a.s.l.).

     

     

    Mean annual sub-surface temperature of the Dreveneuse d'En Bas talus slope. Dr-10 (1570 m a.s.l.) and Dr-11 (1575 m a.s.l.) are located in the lower section of the talus slope, Dr-14 in the uppermost part (1595 m a.s.l.).

     

     

    Daily sub-surface temperature of the Dreveneuse d'En Haut talus slope. Dr-19 (1635 m a.s.l.) is located away from the talus slope at the front of a completely forested relict rock glacier, Dr-21 (1685 m a.s.l.) in the rooting zone of the relict rock glacier at the direct foot of the talus slope, Dr-27 in the uppermost section of the talus slope (1750 m a.s.l.).

     

     

    Mean annual sub-surface temperature of the Dreveneuse d'En Haut talus slope. Dr-19 (1635 m a.s.l.) is located away from the talus slope at the front of a completely forested relict rock glacier, Dr-21 (1685 m a.s.l.) in the rooting zone of the relict rock glacier at the direct foot of the talus slope, Dr-27 in the uppermost section of the talus slope (1750 m a.s.l.).

     

     

    Daily temperature in the borehole F1 located in the middle part (1580 m a.s.l.) of the Dreveneuse d'En Bas talus slope. Permafrost conditions have been episodically observed between 9 and 12 m depth.

     

     

    Mean annual temperature in the borehole F1 located in the middle part (1580 m a.s.l.) of the Dreveneuse d'En Bas talus slope. Permafrost conditions have been episodically observed between 9 and 12 m depth.

     

     

    Daily temperature in the borehole F2 located in the lower part (1570 m a.s.l.) of the Dreveneuse d'En Bas talus slope. Permafrost conditions have been episodically observed between 2 and 3 m depth.

     

     

    Mean annual temperature in the borehole F2 located in the lower part (1570 m a.s.l.) of the Dreveneuse d'En Bas talus slope. Permafrost conditions have been episodically observed between 2 and 3 m depth.

     

     

    Reference (2006-2011) and recent mean annual thermal profile in the boreholes F1 (mid-slope) and F2 (lower slope) in the the Dreveneuse d'En Bas talus slope. Permafrost conditions have been episodically observed between 2 and 3 m depth in F2 and between 9 and 12 m depth in F1.

     

  • Collaboration

    University of Lausanne, Institute of Earth Surface Dynamics (C. Lambiel)

    Meteodat GmbH

    SensAlpin GmbH

    Waljag GmbH

  • Publications

    Mollaret, C., Hilbich, C., Pellet, C., Flores-Orozco, A., Delaloye, R., Hauck, C. (2019). Mountain permafrost degradation documented through a network of permanent electrical resistivity tomography sites. The Cryosphere, 13, 2557–2578, DOI : 10.5194/tc-13-2557-2019.

    PERMOS 2019. Permafrost in Switzerland 2014/2015 to 2017/2018. Noetzli, J., Pellet, C., and Staub, B. (eds.), Glaciological Report (Permafrost) No. 16-19 of the Cryospheric Commission of the Swiss Academy of Sciences, 104 pp, DOI:10.13093/permos-rep-2019-16-19. 

    Pellet, C. and Hauck, C. (2017). Monitoring of soil moisture from middle to high elevation in Switzerland: Set-up and first results from the SOMOMOUNT network. Hydrol. and Earth Syst. Sci., 2, 3199-3220, doi: 10.5194/hess-21-3199-2017

    Morard, S., (2011). Effets de la circulation d'air par effet de cheminée dans l'évolution du régime thermique des éboulis froids de basse et moyenne altitude. PhD thesis, Fac. Sciences, Univ. Fribourg, GeoFocus 29. (pdf)

    Morard, S. & Delaloye R., (2011). Répétition de tomographies de résistivité électrique dans l’éboulis froid ventilé de Dreveneuse d’en Bas (Préalpes du Chablais valaisan, Suisse). Environnements Périglaciaires 17: 5-22.

    Morard, S., (2010). Extrazonal Permafrost in a Low Elevation Talus Slope (Dreveneuse d’en Bas, Swiss Prealps). In Noetzli, J., Naegeli, B., and Vonder Muehll, D. 2010 (eds.). Permafrost in Switzerland 2006/2007 and 2007/2008.Glaciological Report (Permafrost) No. 8/9 of the Cryospheric Commission (CC) of the Swiss Academy of Sciences (SCNAT), p.35-41. (pdf)

    Morard S., Delaloye R., Lambiel C., (2010). Pluriannual thermal behavior of low elevation cold talus slopes (western Switzerland). Geographica Helvetica, 65/2, 124-134. (pdf)

    Morard S., Delaloye R., Dorthe, J. (2008). Seasonal thermal regime of a mid-latitude ventilated debris accumulation.Proceedings of the Ninth International Conference on Permafrost, July 2008, Fairbanks, Alaska, 1233-1238. (pdf)

    Morard S., Delaloye R., Dorthe J. (2008). Indices de fonctionnement de la ventilation des éboulis froids. Proceedings, Swiss Geomorphological Society (SSGm), Annual Meeting 2007, Samedan, Switzerland, 44-56. (pdf)

    Delaloye, R. (2004). Contribution à l’étude du pergélisol de montagne en zone marginale. PhD thesis, Fac. Sciences, Univ. Fribourg, GeoFocus 10 (pdf)