| Summary: | International audience Water infiltration and circulation in bedrock fractures is a potentially key-process in permafrost degradation and rock slope failure triggering. However, hydrological and hydrogeological processes in steep permafrost-affected rock slopes are difficult to investigate because of their non-linearity and anisotropy.In this communication, we will present preliminary results and perspectives of the WISPER project (“Water and Ice related thermo-mechanical processes in the fractures of Steep alpine bedrock Permafrost”, funded by the French National Agency for Research) that aims to improve the understanding of water-related processes in steep permafrost-affected rock slopes. We will introduce the first coupling of thermal and hydrological models applied to steep permafrost-affected rock slopes in a high Alpine granite peak (the Aiguille du Midi, Mont Blanc massif, 3842 m a.s.l.). Four case-studies with a simplified fracture network and various levels of saturation and hydrological forcings have been tested. They confirmed that water infiltration in fractures may accelerate permafrost degradation within them only, and within the rock mass as well, depending on the level of saturation. Furthermore, these simulations demonstrate that water infiltration may also lead to a deeper extent of the permafrost body than originally thought, prompting a rethink of permafrost occurrence at sites where permafrost was considered as non-existent. Finally, these thermo-hydrological simulations serve as a promising tool to assess the role of hydrostatic pressures in triggering rock failure by implementing the results to parameterize mechanical models.Current challenges are related to the quantitative estimation of infiltrating water, notably water produced from snow melting, and to understanding the role of fracture geometry in the acceleration of permafrost degradation and in the development of hydrostatic pressures.
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