Rapid degradation of ground ice in a ventilated talus slope

Auteur(s) et Affiliation(s)



Description :
Two deep boreholes instrumented with thermistors and located in a talus slope at 2400 m asl above a lake at Flüela Pass in the eastern Swiss Alps allow the analysis of the evolution of ground temperature and permafrost thickness between 2003 and 2008. The occurrence of intra-talus ventilation can be discerned due to thermal anomalies within a layer of coarse blocks with large voids at around 15 m depth near the base of the slope and at 10 m depth mid-slope. Despite the lack of annual variability in active layer depth, rapid permafrost degradation and thinning of ground ice is currently occurring. It is attributed to latent heat transfer from the moving air stream, caused by the flux of vapour from the relatively warm lake water table at 20 m depth and its condensation at the base of the permafrost body.


Type de document :
Article de périodique

Source :
Permafrost and periglacial processes, issn : 1045-6740, 2009, vol. 20, n°. 1, p. 1-14, nombre de pages : 14, Références bibliographiques : 2 p.

Date :
2009

Editeur :
Pays édition : Royaume-Uni, Chichester, Wiley