Shallow depth salinisation requires specific AEM survey design and data inversion strategies, such as the constrained inversion technique. This methodology, which is readily applied in the Aarhus Workbench, spreads information between neighboring soudings, allowing a better resolution of model parameters that would be locally poorly resolved.
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Selected different groundwater/environmental applications of Airborne Electromagnetics Dryland salinization, Australia, SkyTEM system. pdf Dryland salinization, Australia, Resolve Fugro HEM system. pdf Coastal seawater intrusion, Australia, Tempest Fugro system. pdf Coastal seawater intrusion, BGR HEM system. pdf Surface-groundwater interactions over Venice lagoon, SkyTEM system. pdf Pollution from waste site, SkyTEM system. pdf Groundwater in large delta environment, VTEM Geotech system. pdf Aarhus Geophysics experience in groundwater application of AEM Groundwater applications of AEM is one of the key expertises of Aarhus Geophysics. Our software was originally designed for groundwater purposes in Denmark, and we have been working intensively with a wide variety of groundwater applications over the years (see "Danish lessons", for an overview of the applicationd of our software in the Danish Environment). The next examples report some of the applications we have been working on over the past few years.
The image represents the near surface average resistivity map from the Bookpurnong area, in South Australia, derived inverting SkyTEM data. This area, like many others in the Darling-Murray catchment zone, is severely affected by salinisation. Click map to enlarge. Click here to find the Exploration Geophysics article published this year about this case study.
Coastal Seawater Intrusion is another frequent problem in large portions of the world, where natural and human driven processes drive the penetration of seawater into groundwater. At the same time, inland aquifers contaminated by industrial activities may lead to offshore pollution. Airborne EM is a powerful tool for mapping sea water intrusion, and for understanding surface groundwater interactions in coastal areas. See for example these expanded abstracts from AEM 2008 in Helsinky (BGR's HEM survey over part of Banda Aceh coast), and from ASEG 2009 in Adelaide (SkyTEM data from Denmark, Fugro's Resolve HEM and Tempest Fixed wing systems data from Australia).· The figure below shows two cross sections from a Tempest survey flown perpendicular to the coast, in south Australia.
Check out also the promising application of AEM over lagoons from this study over the Venice lagoon.· The SkyTEM data, duly processed and inverted with SCI, gave unprecedented insight into the groundwater setting underneath the lagoon, and with respect to the interaction between surface and groundwater. The AEM models identify clearly the depth to the Holocene -Pleistocene boundary, which was also confirmed by sub bottm seismic profiling.
We also invite you to have a look at this expanded abstact presented at the EAGE Near Surface 2009 conference in Dublin. The author use SkyTEM data inverted by Aarhus Geophysics to illustrate the 3D structure of a saltdome in Germany, also visible in the figure below.
Here you can find the expanded abstract from a paper presented at the EAGE conference Near Surface 2009 in Dublin, dealing with mapping of groundwater pollution from waste site with SkyTEM data. As the figure below shows, the AEM data, duly processed and inverted, clearly identified the conductive anomaly in the noisy environment of the waste site.
Average resistivity at 10-15 m below surface
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