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TitleJoining multiple AEM datasets to improve accuracy, cross calibration and derived products: The Spiritwood VTEM and AeroTEM case study
AuthorSapia, V; Viezzoli, A; Oldenborger, G
SourceNear Surface Geophysics vol. 13, no. 1, 2015 p. 61-72, https://doi.org/10.3997/1873-0604.2014041
Year2015
Alt SeriesEarth Sciences Sector, Contribution Series 20140147
PublisherEuropean Association of Geoscientists and Engineers
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceManitoba
NTS73G/05
AreaSpiritwood Valley
Lat/Long WENS-108.0000 -107.5000 53.5000 53.2500
Subjectshydrogeology; geophysics; e m surveys, airborne; magnetic field; conductivity; modelling; aquifers; advanced data processing
Illustrationsmagnetic maps; seismic reflection profiles
ProgramAquifer Assessment & support to mapping, Groundwater Geoscience
AbstractAirborne time-domain electromagnetic methods (AEM) are useful for hydrogeological mapping due to their rapid and extensive spatial coverage and high correlation between measured magnetic fields, electrical conductivity, and relevant hydrogeological parameters. However, AEM data, preprocessing and modelling procedures can suffer from inaccuracies that may dramatically affect the final interpretation. We demonstrate the importance and the benefits of advanced data processing for two AEM datasets (AeroTEM III and VTEM) collected over the Spiritwood buried valley aquifer in southern Manitoba, Canada. Early-time data gates are identified as having significant flightdependent signal bias that reflects survey flights and flight lines. These data are removed from inversions along with late time data gates contaminated by apparently random noise. In conjunction with supporting information, the less-extensive, but broader-band VTEM data are used to construct an electrical reference model. The reference model is subsequently used to calibrate the AeroTEM dataset via forward modelling for coincident soundings. The procedure produces calibration factors that we apply to AeroTEM data over the entire survey domain. Inversion of the calibrated data results in improved data fits, particularly at early times, but some flight-line artefacts remain. Residual striping between adjacent flights is corrected by including a mean empirical amplitude correction factor within the spatially constrained inversion scheme. Finally, the AeroTEM and VTEM data are combined in a joint inversion. Results confirm consistency between the two different AEM datasets and the recovered models. On the contrary, joint inversion of unprocessed or uncalibrated AEM datasets results in erroneous resistivity models which, in turn, can result in an inappropriate hydrogeological interpretation of the study area.
Summary(Plain Language Summary, not published)
Airborne electromagnetic geophysics surveys are useful for aquifer mapping due to rapid and extensive spatial coverage. However, proper data processing and modelling are required to ensure reliable products. We compare two different airborne electromagnetic datasets over the Spiritwood buried valley aquifer in southern Manitoba. We demonstrate the importance of data processing and calibration on the resulting geological models and we discuss implications for hydrogeological interpretations.
GEOSCAN ID295055