1887
Volume 57, Issue 4
  • E-ISSN: 1365-2478

Abstract

ABSTRACT

Previous studies using commercial airborne electromagnetic equipment that is not optimized for marine surveying have demonstrated the use of airborne electromagnetic methods for measuring water depth and estimating sediment thickness. A new prototype helicopter time‐domain airborne electromagnetic system, SeaTEM(0), is now under development for bathymetric surveying. The first sea trial of the SeaTEM(0) system took place over Broken Bay, New South Wales, Australia, in shallow water up to ∼30 m in depth. Broken Bay was chosen because the separate paleodrainage systems for the Hawkesbury River, Brisbane Water and Pittwater, which join in Broken Bay give rise to paleovalleys infilled with unconsolidated sediments, ranging in thickness between 0 m (bedrock outcrop) and ∼200 m. The survey area also included a tombolo with a beach either side, which provided the opportunity to measure water depth through a surf zone. Sediment thickness and water depth is predicted from stitched layered‐earth inversion of data based on a simplified two‐layer model that represents seawater and sediment overlying a resistive half‐space basement (bedrock). The resulting bathymetric profiles show agreement typically to within ∼±1 m and ∼±0.5 m with known water depths in areas less than 20 and 6 m deep respectively. The inverted depth profile of the second (sediment) layer is noisy; however, the profiles reveal coarse topographic features of paleovalleys to depth limits of ∼60 to 80 m below sea level in 20 to 30 m water depth, as well as resolving bedrock ridges and exposed reefs in shallow waters.

Loading

Article metrics loading...

/content/journals/10.1111/j.1365-2478.2008.00762.x
2008-12-23
2024-04-25
Loading full text...

Full text loading...

References

  1. AlbaniA.D.1974. Sedimentary environments in Broken Bay, NSW. Journal of the Geological Society of Australia21, 279–290.
    [Google Scholar]
  2. AlbaniA.D. and JohnsonB.D.1974. The bedrock topography and origin of Broken Bay, NSW. Journal of the Geological Society of Australia21, 209–214.
    [Google Scholar]
  3. AlbaniA.D., TaytonJ.W., RickwoodP.C., GordonA.D. and HoffmanJ.G.1988. Cainozoic morphology of the inner continental shelf near Sydney, NSW. Journal and Proceedings of the Royal Society of New South Wales121, 11–28.
    [Google Scholar]
  4. BennettR.H., LambertD.N., HulbertM.H., BurnsJ.T., SawyerW.B. and FreelandG.L.1983. Electrical resistivity/conductivity in seabed sediments. In: CRC Handbook of Geophysical Exploration at Sea (ed. R.A.Geyer ), pp. 333–375. CRC Press.
    [Google Scholar]
  5. BoydG.L.2004. HoistEM – a new airborne electromagnetic system. In: PACRIM 2004, September 2004 . Australian Institute of Mining and Metallurgy. ISBN 9781920806187.
    [Google Scholar]
  6. BrodieR. and SambridgeM.2006. A holistic approach to inversion of frequency‐domain airborne EM data. Geophysics71, G301–G312.
    [Google Scholar]
  7. DavisA.C. and MacnaeJ.2008. Quantifying AEM system characteristics using a ground loop. Geophysics73, F179–F188
    [Google Scholar]
  8. DavisA.C., MacnaeJ. and RobbT.2006. Pendulum motion observed in HEM systems. Exploration Geophysics37, 355–362.
    [Google Scholar]
  9. FullagarP.K. and OldenburgD.W.1984. Inversion of horizontal loop electromagnetic frequency soundings. Geophysics49, 150–164.
    [Google Scholar]
  10. GuentherG.C., LillycropW.J. and BanicJ.R.2002. Future advancements in airborne hydrography. International Hydrographic Review3, 67–90.
    [Google Scholar]
  11. HuttJ. and BergJ.W.Jr. 1968. Thermal and electrical conductivities of sandstone and ocean sediments. Geophysics33, 489–500.
    [Google Scholar]
  12. JacksonP.D., Taylor SmithD. and StanfordP.N.1978. Resistivity‐porosity‐particle shape relationships for marine sands. Geophysics43, 1250–1268.
    [Google Scholar]
  13. KermabonA., GehinC. and BlavierP.1969. A deep‐sea electrical resistivity probe for measuring porosity and density of unconsolidated sediments. Geophysics34, 554–571.
    [Google Scholar]
  14. KratzerT. and VrbancichJ.2007. Real‐time kinematic tracking of towed AEM birds. Exploration Geophysics38, 132–143.
    [Google Scholar]
  15. De LevieR. 2004. Advanced Excel for Scientific Data Analysis . Oxford University Press. ISBN 0195152751.
    [Google Scholar]
  16. PalackyG.J. and WestG.F.1991. Airborne electromagnetic methods. In: Electromagnetic Methods in Applied Geophysics – Theory, 2 . Part B. (ed. M.N.Nabighian ), pp. 811–879. SEG. ISBN 156080224.
    [Google Scholar]
  17. SchonJ.H.1996. Handbook of Geophysical Exploration, Volume 18, Physical Properties of Rocks: Fundamentals and Principles of Petrophysics . Pergamon.
    [Google Scholar]
  18. VrbancichJ. and FullagarP.K.2004. Towards seawater depth determination using the helicopter HoisTEM system. Exploration Geophysics35, 292–296.
    [Google Scholar]
  19. VrbancichJ. and FullagarP.K.2007a. Towards remote sensing of sediment thickness and depth to bedrock in shallow seawater using airborne TEM. Exploration Geophysics38, 77–88.
    [Google Scholar]
  20. VrbancichJ. and FullagarP.K.2007b. Improved seawater depth determination using corrected helicopter time domain electromagnetic data. Geophysical Prospecting55, 407–420.
    [Google Scholar]
  21. VrbancichJ., SattelD., AnnettsD., MacnaeJ. and LaneR.2005a. A case study of AEM bathymetry in Geographe Bay and over Cape Naturaliste, Western Australia, Part 1: 25 Hz QUESTEM. Exploration Geophysics36, 301–309.
    [Google Scholar]
  22. VrbancichJ., MacnaeJ., SattelD. and WolfgramP.2005b. A case study of AEM bathymetry in Geographe Bay and over Cape Naturaliste, Western Australia, Part 2: 25 and 12.5 Hz GEOTEM. Exploration Geophysics36, 381–392.
    [Google Scholar]
  23. WonI.J. and SmitsK.1986. Application of the airborne electromagnetic method for bathymetric charting in shallow oceans. In: Airborne Resistivity Mapping: Geological Survey Canada, Paper 86–22 (ed. G.J.Palacky ), pp. 99–104.
    [Google Scholar]
  24. ZollingerR., MorrisonH.F., LazenbyP.G. and BeckerA.1987. Airborne electromagnetic bathymetry. Geophysics52, 1127–1137.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.1111/j.1365-2478.2008.00762.x
Loading
/content/journals/10.1111/j.1365-2478.2008.00762.x
Loading

Data & Media loading...

  • Article Type: Research Article

Most Cited This Month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error