B. Siemon,A. Ullmann, M. Ibs-von Seht, W. Voß, J. Pielawa Airborne Geophysical Investigations of CLIWAT Pilot Areas Survey Area Friesland, The Netherlands, 2009 Interreg IVB Project: CLIWAT – Adaptive and sustainable water management and protection of society and nature in an extreme climate Bundesanstalt für Geowissenschaften und Rohstoffe Federal Institute for Geosciences and Natural Resources CLIWAT – Adaptive and sustainable water management and protection of society and nature in an extreme climate Survey Area Friesland, The Netherlands 2009 Technical Report on the Interreg IVB Project The project is part-financed by the European Union In Cooperation with TNO Deltares Wetterskip Fryslân Provincje Fryslân Authors: B. Siemon A. Ullmann M. Ibs-von Seht W. Voß J. Pielawa Date: December 15, 2010 Airborne Geophysical Investigations of CLIWAT Pilot Areas – I – Survey Area Friesland, The Netherlands, 2009 Table of contents Personnel ....................................................................................................................... III List of figures .................................................................................................................. IV List of tables .....................................................................................................................V List of maps .................................................................................................................... VI List of vertical resistivity sections .................................................................................. VII Abbreviations ............................................................................................................... VIII 1. Summary .................................................................................................................... 1 2. Introduction .............................................................................................................. 3 3. Survey Area ................................................................................................................ 6 4. Airborne Geophysical System ..................................................................................... 8 4.1. The Helicopter.............................................................................................................................. 9 4.2. Measuring System........................................................................................................................ 9 4.3. Electromagnetics ........................................................................................................................ 10 4.4. Magnetics ................................................................................................................................... 11 4.5. Radiometrics .............................................................................................................................. 12 4.6. Navigation and Positioning ....................................................................................................... 13 4.7. Data Acquisition and Recording ................................................................................................ 15 4.8. Video System .............................................................................................................................. 15 4.9. Additional Equipment ............................................................................................................... 16 5. Processing and Presentation of the Survey Data ....................................................... 17 5.1. General Processing Steps ........................................................................................................... 17 5.2. Position Data .............................................................................................................................. 18 5.2.1. Coordinates .......................................................................................................................... 18 5.2.2. Radar Altitude ...................................................................................................................... 18 5.2.3. Laser Altitude ....................................................................................................................... 18 5.2.4. Topographic Elevation ........................................................................................................ 19 5.3. Processing of the Electromagnetic Data ................................................................................... 20 5.3.1. Calibration of the HEM System .......................................................................................... 20 5.3.2. Zero-Level and Drift Correction ......................................................................................... 21 5.3.3. Data Correction ................................................................................................................... 21 5.3.4. Conversion of the Secondary Field Values to Half-Space Parameters .............................. 22 5.3.5. Effect of Anthropogenic Influences on the HEM Data ...................................................... 24 Airborne Geophysical Investigations of CLIWAT Pilot Areas – II – Survey Area Friesland, The Netherlands, 2009 5.3.6. Statistical Levelling.............................................................................................................. 25 5.3.7. 1-D Inversion of the HEM Data .......................................................................................... 26 5.3.8. Presentation of the Results ................................................................................................. 27 5.4. Processing of Magnetic Data ..................................................................................................... 28 5.4.1. Magnetic Total Field ............................................................................................................ 28 5.4.2. IGRF ..................................................................................................................................... 28 5.4.3. Diurnal Variations ............................................................................................................... 28 5.4.4. Levelling ............................................................................................................................... 28 5.4.5. Presentation of the Results ................................................................................................. 29 5.5. Processing of Gamma-Ray Spectrometry Data ........................................................................ 30 5.5.1. Energy Calibration ............................................................................................................... 30 5.5.2. Reduction of Statistical Noise ............................................................................................. 31 5.5.3. Detector Height above Ground and Effective Height ........................................................ 31 5.5.4. Live Time Correction ........................................................................................................... 32 5.5.5. Background Radiation Correction ...................................................................................... 32 5.5.6. Compton Correction ............................................................................................................ 33 5.5.7. Height-Attenuation Reduction ........................................................................................... 33 5.5.8. Radioelement Concentrations and Exposure Rate ............................................................ 34 5.5.9. Data Levelling and Smoothing ............................................................................................ 36 5.5.10. Presentation of the Results ................................................................................................ 36 6. Cartographic Work ................................................................................................... 37 6.1. Topographic Map ....................................................................................................................... 37 6.2. Map Production with GEOSOFT and GIS Software ................................................................. 37 6.3. Thematic Maps ........................................................................................................................... 38 7. Archiving ................................................................................................................. 39 8. References ............................................................................................................... 40 Signatures ....................................................................................................................... 41 Appendix I: Survey Area Friesland ................................................................................... 42 Appendix II: Final Data Format Description .................................................................... 46 Appendix III: DVD ........................................................................................................... 56 Appendix IV: Maps .......................................................................................................... 60 Appendix V: Vertical Resistivity Sections .......................................................................