Géodynamique du pergélisol alpin : fonctionnement, distribution et évolution récente. L'exemple du massif du Combeynot (Hautes Alpes)

Abstract : This study intends to understand the state and the functioning of the mountain permafrost in a crystalline and poorly glacierised massif (Combeynot Massif, Hautes Alpes, France) on one hand, and on the other hand to express its distribution and evolution at variable spatial and temporal scales. First, the monitoring devices, helped by three very different years in nivo-meteorological terms, have revealed some of the main features of the thermal processes at the Laurichard rockglacier surface. The spatialisation of the winter surface temperatures clearly shows the influence of the very warm 2003 summer followed by the snowy 2003-2004 winter, that both contributed to prevent the cooling of the ground. This relation with the seasonal snow history, especially in early winter, is also demonstrated by the analysis of the annual velocity of the rockglacier and of the climatic data during the last two decades. At the scale of the whole massif, the relation climate/permafrost has been modelled by a statistico-empirical relationship which reproduces the influence of the topoclimatic conditions on the permafrost. Four case studies have nevertheless revealed that the geodynamical context and its evolution during the Quaternary are essential in understanding the state and the distribution of the permafrost at slope and watershed scales. Finally, the recent climate warming seems to have induced a temporary speed-up of the creeping velocity of the permafrost, which subsequently arises the question of the stability of degrading slopes.
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Geomorphology. Université Paris-Diderot - Paris VII, 2007. French


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Submitted on : Wednesday, January 9, 2008 - 2:11:16 PM
Last modification on : Friday, February 27, 2015 - 1:11:35 AM

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Xavier Bodin. Géodynamique du pergélisol alpin : fonctionnement, distribution et évolution récente. L'exemple du massif du Combeynot (Hautes Alpes). Geomorphology. Université Paris-Diderot - Paris VII, 2007. French. <tel-00203233>

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