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TitreJoining multiple AEM datasets to improve accuracy, cross calibration and derived products: The Spiritwood VTEM and AeroTEM case study
AuteurSapia, V; Viezzoli, A; Oldenborger, G
SourceNear Surface Geophysics vol. 13, no. 1, 2015 p. 61-72, https://doi.org/10.3997/1873-0604.2014041
Année2015
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140147
ÉditeurEuropean Association of Geoscientists and Engineers
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.3997/1873-0604.2014041
Mediapapier; en ligne; numérique
Formatspdf
ProvinceManitoba
SNRC73G/05
Lat/Long OENS-108.0000 -107.5000 53.5000 53.2500
Sujetslevés aéroélectromagnétiques; champ magnétique; conductivité; établissement de modèles; aquifères; hydrogéologie; géophysique
Illustrationsmagnetic maps; seismic reflection profiles
ProgrammeAquifer Assessment & support to mapping, Géoscience des eaux souterraines
Résumé(disponible en anglais seulement)
Airborne 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.
Résumé(Résumé en langage clair et simple, non publié)
Les levés aériens géophysiques électromagnétiques sont utiles pour la cartographie de l'aquifère en raison de la couverture spatiale rapide et importante. Toutefois, le traitement des données et de modélisation sont nécessaires pour garantir des produits fiables. Nous comparons les deux ensembles de données électromagnétiques aéroportés différents pour l'aquifère de la vallée Spiritwood dans le sud du Manitoba. Nous démontrons l'importance du traitement des données et l'étalonnage sur les modèles géologiques résultant et nous discutons des implications pour les interprétations hydrogéologiques.
GEOSCAN ID295055