Slope morphodynamics in periglacial environments: data from physical modelling.

• Main Author: Védie, Emeric
• Other Authors: Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Université de Caen, Jean-Louis LAGARDE
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2008
• Subjects: Geomorphology; freeze-thaw cycles; debris flow; physical modelling; climate warming; Géomorphologie; Périglaciaire; Gel-dégel; Coulée de débris; Modélisation physique; Réchauffement climatique; Mars; Martian gullies; Erosion; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; permafrost
• Online Access: https://tel.archives-ouvertes.fr/tel-00324815; https://tel.archives-ouvertes.fr/tel-00324815/document; https://tel.archives-ouvertes.fr/tel-00324815/file/THESE_VEDIE_2008.pdf

Physical modelling in cold room is used here to constrain the impact of climate changes on landscape evolution, in periglacial environments. Experimental data attest (i) the role of active layer moisture regime on slow and rapid slope processes and (ii) that changes in thermal and moisture regimes influence both erosion rate and slope morphodynamics. -When rainfall is moderate, cryoexpulsion, frost creep/gelifluction and gravity slides processes modify the slope morphology (progressive upward erosion). - When heavy rainfall is applied to the model, rapid slope processes prevail leading to the more marked slope degradation. Their triggering is controlled by (i) topography and particularly by steeper slopes and (ii) by the occurrence of a permafrost at deep which minimizes water infiltration and plays the role of a slip surface. The highest erosion rates are related to heavy rainfall. These experiments bring new data showing that slopes with permafrost are particularly sensitive to changes in thermal and moisture regime. They should (i) constitute a precious help for establishing an in situ measuring methodology for periglacial systems and (ii) improve the knowledge of landscape evolution in periglacial environments, when climate warming increases both the thaw of the permafrost and the abundance of water during spring thawing. This study must be now focalised on the control exerted by soil saturation dynamics on slope erosion processes. La modélisation physique en enceinte de gel est utilisée pour analyser les impacts du réchauffement climatique sur l'évolution des paysages en contexte périglaciaire. Les données expérimentales nous montrent (i) l'importance des conditions de saturation de la couche active dans le déclenchement des mécanismes lents et rapides des sols et (ii) l'impact des perturbations des régimes thermiques et hydriques du sol qui modifient à la fois les taux d'érosion et la dynamique des versants périglaciaires. - Lors de précipitations modérées, cryoexpulsion, cryoreptation/gélifluxion et ...