Coupled thermo-geophysical inversion for permafrost monitoring

• Main Authors: Tomaskovicova, Sona, Ingeman-Nielsen, Thomas
• Format: Conference Object
• Language: English
• Published: 2018
• Subjects: Geoelectrical monitoring; Coupled inversion; Permafrost; Time-lapse ERT; Heat transfer; Arctic; Greenland; Ilulissat; permafrost
• Online Access: https://orbit.dtu.dk/en/publications/3fffdcb5-529d-4e97-a050-e6edf1a911f7

We describe an approach to calibrating the thermal parameters of a ground undergoing cycles of freezing and thawing using exclusively time-lapse geoelectrical measurements collected from the ground surface. The method links a heat conduction model with a ground resistivity model in a fully coupled optimization approach. The data used for model calibration come from a high-latitude permafrost monitoring site in Ilulissat, West Greenland. Parameters calibrated on time-lapse geoelectrical data reproduce the calibration dataset with an accuracy comparable to that of a calibration on borehole temperature data, and reproduce the observed borehole temperatures to within ±0.6 °C. Given the underdetermined nature of the inverse problem and the simplicity of the heat model, the parameter values are non-uniquely determined in both calibration approaches. Nevertheless, the method offers the possibility of gaining an outlook of ground thermal conditions over a larger area, at lower cost and with reduced impact on the fragile arctic environment.