Effects of ice content on the thermal erosion of permafrost : implications for coastal and fluvial erosion

• Published in: Permafrost and Periglacial Processes
• Main Authors: Dupeyrat, L., Costard, F., Randriamazaoro, R., Gailhardis, E., Gautier, E., Fedorov, A.
• Other Authors: Interactions et dynamique des environnements de surface (IDES), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Melnikov Permafrost Institut, Russian Academy of Sciences Moscow (RAS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Ice; permafrost; Permafrost and Periglacial Processes
• Online Access: https://hal.science/hal-00601113; https://doi.org/10.1002/ppp.722

International audience The effects of ice content and water flow on thawing and erosion of non-cohesive permafrost banks were investigated through laboratory experiments. A critical ice content was identified as associated with turbulent flows (20% and 80% for Reynolds numbers of 15 900 and 12 700, respectively), above which thermal erosion results in ablation and a decrease in ice content increases ablation. Below the critical value, the ablation model over-estimates the erosion rate as the removal of thawed sediments occurs episodically, possibly due to the imbrication of sand grains. The ablation model applies to rivers with non-cohesive banks, high ice contents and subject to high-velocity water flows. The model may explain differential erosion that results in massive ice layers in relief. At other sites, however, the retreat rate increases with ground ice content. This behaviour can be explained for sandy permafrost with a relatively low ice content and heterogeneous sand sizes and shapes subject to relatively low-velocity water flow. These results apply only to perenially frozen sands, as even a small percentage of cohesive material would modify the relationships described. Copyright (c) 2011 John Wiley & Sons, Ltd.