Umiujaq, northern Québec: innovative techniques to monitor the decay of a lithalsa in response to climate change

• Published in: Permafrost and Periglacial Processes
• Main Authors: Georg Delisle, Michel Allard, Richard Fortier, Fabrice Calmels, É. Larrivée
• Format: Article in Journal/Newspaper
• Language: unknown
• Subjects: Hudson; Hudson Bay; Umiujaq; Ice; permafrost
• Online Access: https://doi.org/10.1002/ppp.469

We describe the introduction of several new techniques to measure and monitor permafrost properties at a site near the east coast of the Hudson Bay, northern Québec. Eight boreholes were sunk through a lithalsa to the permafrost base. High precision temperature sensors and a pressure sensor were installed in six boreholes to monitor the long‐time changes of the thermal field of the permafrost and internal pore pressure. Two open boreholes were used to carry out a ground penetrating radar transillumination survey to provide a tomographic image of the spatial distribution of electromagnetic wave velocities within the lithalsa. Cores taken from the permafrost below the active layer of the lithalsa show numerous oblique and fractured ice lenses indicative of extensive deformation of the lithalsa during its evolution. Examples of results of the new techniques applied in this study are provided. These techniques appear as very promising for permafrost studies in general. Copyright © 2003 John Wiley & Sons, Ltd.