Mapping subsurface conditions within the near-shore zone of an Arctic delta using ground penetrating radar

Abstract This paper demonstrates the capabilities of ground penetrating radar (GPR) to map and resolve shallow subsurface features in the near-shore zone: (i) ice conditions (floating or bottom fast); (ii) water bathymetry; (iii) sedimentary structures; and (iv) interfaces between frozen and unfrozen sediment. These features were resolved in the near-shore zone of the Mackenzie Delta, N.W.T., Canada, using multi-frequency (50, 100 and 250 MHz) GPR data collected in winter (2005 and 2006). The capability of GPR to resolve subsurface features in the near-shore zone was strongly controlled by bottom-fast and floating ice conditions. The latter were discriminated using a novel approach involving the energy return from the base of ice and the presence of ice-bottom multiples. Beneath zones of bottom-fast ice, sedimentary structures and interfaces between frozen and unfrozen sediment were discriminated by reflection geometry and amplitude. Beneath floating ice, water depths were measured to depths greater than 5 m using a multi-layer depth calculation. Overall, this research demonstrates that baseline information for geotechnical investigations and climate change research in Arctic coastal zones can be greatly enhanced with GPR data.

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