D–AERO: Airborne geophysical surveys for mapping the shallow subsurface in Germany – Evaluation

Country / Region: Germany

Begin of project: April 1, 2016

End of project: March 31, 2020

Status of project: March 31, 2020

Projekt-Logo D-AERO

Within the D-AERO-Projekt starting in 2007, eight airborne surveys at the German North Sea coast were conducted using the BGR helicopter survey system. These and older surveys are merged within this evaluation project. The resulting datasets are provided with respect to INSPIRE formats. They are available via BGR-Produktcenter (download) and viewable at BGR-Geoviewer. The results are also stored in an information system (FIS-Geophysik LIAG).

The knowledge of the subsurface down to about one hundred metres is fundamental for a variety of economic, ecological and geoscientific tasks, e.g. water use concepts, land use planning, industrial planning, landfill facilities, urban planning, road construction, mining, restoration measures, enlargement of conservation areas, flood plain zoning.

So far, in Germany mapping was usually carried out on a local to regional scale by ground-based methods but only where they were required by law or where specific geoscientific studies were performed. Such ground-based surveys are inefficient to map large areas and airborne surveys are mandatory. Furthermore, airborne surveys are able to provide data sets, which could be linked to other spatial data sets. That is fundamental as, e.g., a change in land use can also change the water balance and a change of the groundwater table is important for urban or transport infrastructure planning.

Besides the tremendous benefits for any kind of land planning and major civil engineering activities particularly airborne geophysics provides a great opportunity for the German geosciences: In the first hundred metres of the subsurface the fundamental exchange and transport processes take place, e.g. for salts and other minerals, fertilizers and pollutants, etc. In addition, information obtained about surface layers may help to understand the development of sedimentary basin structures.

Displaying the airborne geophysical results with respect to high-resolution elevation models enables to link surface data with spatial geophysical data. A spatial geographic information system for surface and subsurface is an ideal planning tool to document temporal-spatial changes in addition to the geological-geophysical base-line data.

High-resolution airborne geophysical surveys exist only for certain areas, which are located mainly in the northern part of Germany. Since 2007, BGR has used the helicopter system to complete and gradually merge surveys at the North German coast and to test airborne geophysics for new thematic mapping.

Aerogeophysical survey areas of BGR in Northern Germany Source: BGR

Airborne electromagnetics is suitable to reveal electrical conductivities within the upper hundred metres of the subsurface and provides very useful information for hydrogeological and geological interpretation. This enables mapping of groundwater systems, clay layers, salinisation and other conductive structures.

Airborne magnetics helps to investigate deep seated rocks of different magnetization, regional fault systems, such as the Rhine Valley, and near-surface disposal sites.

Airborne radiometrics measures the natural gamma radiation of the surface (upper few decimetres) as well as the man-made sources and can, for example, be used to distinguish different types of soil. It is particularly suitable for the comparison with high-resolution satellite images.

Together with other geophysical and geological knowledge of the subsurface, interpretation of airborne geophysical data with respect to a wide range of application is possible (Siemon et al., 2020):

Groundwater mapping,
Determination of saltwater/freshwater boundaries,
Mapping of saltwater rise zones,
Control of large dikes,
Mapping of fault zones in bedrock,
Geological mapping of the shallow subsurface,
Differentiation of sediments and hard rocks,
Exploration of mineral and non-mineral resources,
Site investigation and soil investigations of large-scale plants,
Investigation for traffic route engineering,
Location of contaminated land, landfill mapping, landfill leachates,
Sensing and monitoring of contaminated sites,
Repository exploration,
Archaeological reconnaissance surveys,
etc.

Literature

Publications

Costabel, S., Siemon, B., Houben, G. & Günther, T., 2017. Geophysical investigation of a freshwater lens on the island of Langeoog: Insights from combined HEM and MRS data. Journal of Applied Geophysics, 136, 231-245, doi: 10.1016/j.jappgeo.2016.11.007.

Siemon, B., Christiansen, A.V. & Auken, E., 2009. A review of helicopter-borne electromagnetic methods for groundwater exploration. Near Surface Geophysics, 7, 629-646, doi: 10.3997/1873-0604.2009043.

Siemon, B., Costabel, S., Voß, W., Meyer, U., Deus, N., Elbracht, J., Günther, T. & Wiederhold, H., 2015. Airborne and ground geophysical mapping of coastal clays in Eastern Friesland, Germany. Geophysics, 80 (3), WB21-WB34, doi: 10.1190/GEO2014-0102.1.

Siemon, B., Ibs-von Seht, M. Steuer, A., Deus, N. & Wiederhold, H., 2020. Airborne electromagnetic, magnetic, and radiometric surveys at the German North Sea Coast applied to groundwater and soil investigations. Remote Sensing, 12(10), 1629, doi: 10.3390/rs12101629.

Siemon, B., Steuer, A., Deus, N. & Elbracht, J., 2018. Comparison of manually and automatically derived fresh-saline groundwater boundaries from helicopter-borne EM data at the Jade Bay, Northern Germany. E3S Web of Conferences, 54, 00032, 6p, doi: 10.1051/e3sconf/20185400032.

Steuer, A., Siemon, B. & Auken, E., 2009. A comparison of helicopter-borne electromagnetics in frequency- and time-domain at the Cuxhaven valley in Northern Germany. Journal of Applied Geophysics, 67 (3), 194-205. doi: 10.1016/j.jappgeo.2007.7.001.

Sulzbacher, H., Wiederhold, H., Siemon, B., Grinat, M., Igel, J., Burschil, T., Günther, T. & Hinsby, K., 2012. Numerical modelling of climate change impacts on freshwater lenses on the North Sea Island of Borkum using hydrological and geophysical methods. Hydrol. Earth Syst. Sci., 16, 3621–3663, doi: 10.5194/hess-16-3621-2012 (online: http://www.hydrol-earth-syst-sci.net/16/3621/2012/hess-16-3621-2012.pdf).

Wiederhold, H., Scheer, W., Sulzbacher, H., Siemon, B. & Kirsch, R., 2015. Nordseeinseln im Klimawandel – die Nordfriesische Insel Föhr und die Ostfriesische Insel Borkum, In: Tillmann, T. (ed.), Aktuelle Küstenforschung an der Nordseeküste, Coastline Reports 25, 45-58.

Conference contributions

Ibs-von Seht, M. & Siemon, B., 2010. Hochaufgelöste aeromagnetische Messungen im Elbe-Weser-Küstenraum. Poster, 70. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, 15.–18.3.2010, Bochum, GG-P07.

Schaumann, G., Steuer, A., Siemon, B., Wiederhold, H. & Binot, F., 2010. Die deutsche Nordseeküste im Fokus aeroelektromagnetischer Untersuchungen, Teilgebiete Langeoog mit Wattenmeer und Elbemündung. In: Ritter, O. & Weckmann, U. (Ed) Proceedings of the 23rd Schmucker-Weidelt-Colloquium for Electromagnetic Depth Research, Potsdam, ISSN 0946-7467, 177-187.

Siemon, B., Steuer, A., Deus, N. & Elbracht, J., 2018. Fresh-saline groundwater boundaries derived from helicopter-borne EM data in Northern Germany. 7th International Workshop on Airborne Electromagnetics, 17.-20.6.2018, Kolding, Denmark. Poster.

Siemon, B., Steuer, A., Ibs-von Seht, M., Miensopust, M.P., Meyer, U. & Wiederhold, H., 2012. Airborne geophysical surveys in the Weser-Elbe area, Northern Germany. 21th International Workshop on Electromagnetic Induction in the Earth, 25.-31.8.2012, Darwin, Australia.

Siemon, B., Steuer, A. & Meyer, U., 2018. Review of BGR’s HEM surveys in Germany. 7th International Workshop on Airborne Electromagnetics, 17.-20.6.2018, Kolding, Denmark. Poster.

Siemon, B., Wiederhold, H., Steuer, A., Miensopust, M.P., Voß, W., Ibs-von Seht, M. & Meyer, U., 2014. Helicopter-borne electromagnetic surveys in Northern Germany. In: Wiederhold, H., Michaelsen, J., Hinsby, K. & Nommensen, B. (Eds.) Programme and Proceedings of SWIM 2014, 23rd Salt Water Intrusion Meeting 2014, 15.-22.6.2014, Husum, 375-378.

Siemon, B., Wiederhold, H., Steuer, A., Voß, W. & Meyer, U., 2014. Hubschraubergeophysikalische Messungen in Norddeutschland. In: Tagungsband zur 74. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, 10.-13.3.2014, Karlsruhe, EM-P.009.

Siemon, B., Wiederhold, H., van Baaren, E., Dabekaussen, W., Ullmann, A., Steuer, A., Delsman, J. & Gunnink, J., 2017. Regionale Grundwassererkundung an der Nordseeküste mit der Hubschrauberelektromagnetik. In: Becken, M. & Hölz, S. (Hrsg.), Protokoll über das 27. Schmucker-Weidelt-Kolloquium für Elektromagnetische Tiefenforschung, Breklum, 25.-29. September 2017, 108.

Steuer, A., Siemon, B. & Grinat, M., 2010. The German North Sea Coast in Focus of Airborne Electromagnetic Investigations: The Freshwater Lenses of Borkum. In: Ritter, O. & Weckmann, U. (Ed) Proceedings of the 23rd Schmucker-Weidelt-Colloquium for Electromagnetic Depth Research, Potsdam, ISSN 0946-7467, 188-197.

Steuer, A., Siemon, B., Schaumann, G., Wiederhold, H., Meyer, U., Pielawa, J., Binot, F. & Kühne, K., 2009. The German North Sea Coast in Focus of Airborne Geophysical Investigations. – AGU Fall Meeting 2009, San Francisco, USA.

Wiederhold, H., Binot, F., Kühne, K., Meyer, U., Siemon, B. & Steuer, A., 2008. Airborne geophysical investigation of the German North Sea Coastal Area. – 20th Salt Water Intrusion Meeting 2008, Naples, USA.