S07: Airborne Geophysics recent advances and novel applications

Accurate AEM data processing in hydrogeological projects… is it worth the time, pain and $ ?

Viezzoli, Soerensen, Jorgensen……

Airborne Electromagnetics is used in many countries as a major tool for groundwater management, and environmental management, including parts of biosphere. In Denmark and Australia, for example, the geological surveys have, and continue to do so, acquired large datasets covering relevant portions of their sensitive areas, for this kind of applications. In both countries there is a high level of attention to the quality of the source data, of their processing and modeling, of the integration of results with ancillary information in order to produce derived products. In this paper we assess the effects that different levels of processing of Helicopter TEM data have on the resulting electrical models and then on the hydrogeological models. We use a SkyTEM dataset from XXX in Denmark, acquired in 2009. We focus on different approaches in the processing of the raw data found in the industry, whilst inversion, which is necessary to show the effect in the model space, is undertaken in rather standard way. We show how the electrical models, and then the hydrogeology, change depending on the level of decoupling of artifacts, of lateral averaging, of late time noise assessment, and compare it with available borehole information. Each one of these processing steps alters the output, and therefore the derived models. With respect to under/overextimating the depth to bedrock by several tens of metres, or the absolute resistivities by hundreds of Ohm m, and therefore potentially assigning the wrong hydrogeological unit to a given electrical layer, the extra time, effort and monetary investment involved in accurate detailed processing is probably worthwhile.