Towed transient electromagnetic survey results at Ilulissat, Greenland for water vulnerability and infrastructure planning

The area around Ililissat, Greenland hosts a complex permafrost environment, situated in an area with saline sediments resulting in varying freezing conditions. Expansion of infrastructure and the vulnerability of the surficial water supply of the town is dependent on these conditions, especially in a warming climate. We have conducted a towed transient electromagnetic survey covering approximately 640 hectares in the areas west and east of the town to spatially elucidate these conditions. The presence of saline sediments, varying permafrost conditions, and complicated basement structure require inversion techniques beyond the standard resistivity-only methods--induced polarisation (IP) phenomena are ubiquitous in the survey area. As such we employ a reparameterisation of the Cole-Cole equation known as maximum phase angle (MPA) inversion capable of recovering resistivity and IP models. We show that the MPA approach can successfully invert data expressing IP signal, allowing for detailed geologic, hydrologic, and cryologic interpretation of the survey area.