Advertisement

Application of the Helicopter Frequency Domain Electromagnetic Method for Levee Characterization

  • Adam SmiarowskiEmail author
  • Greg Hodges
  • Joe Dunbar
Chapter

Abstract

Levee characterization requires many miles of ground to be surveyed. Remote sensing methods, particularly those capable of installation on an aircraft, are capable of quickly surveying large areas. The helicopter frequency domain electromagnetic technique (HEM) involves towing an electromagnetic transmitter and receiver that measure signals proportional to the electrical conductivity of the ground. Information about the electrical conductivity of the ground can be used to make inferences about the distribution of soils or rocks in the subsurface. HEM data can be interpreted by correlating the apparent conductivity to soil or rock type, as well as for looking for lateral and depth extent of anomalous zones. HEM data provide depth information by performing measurements at different frequencies. Here, we provide a brief review of the frequency domain method, highlighting the transformation of HEM data to apparent resistivity, which is critical for interpretation. We then discuss two case histories using an HEM system for levee characterization and hazard detection. With clay being the primary building material for the levees, the minimum layer thickness that can be accurately resolved with an upper frequency of 140 kHz is about 1 m. The HEM data are particularly useful at detecting anomalous zones for follow up investigation. These zones were caused by underground channels (which provide pathways for water flow) and in one case by significant cracking of a levee. The examples provided here highlight the utility of HEM surveying for levee characterization.

References

  1. Amine, D., Hodges, G. H., Selvamohan, S., and Marlow, D. Correlating Helicopter EM and Borings for Levee Evaluation Studies in California. Symposium on the Application of Geophysics to Engineering and Environmental Problems 2009: pp. 126–134.Google Scholar
  2. Dunbar, J.B., Llopis, J.L., Sills, G.L., Smith, E.W., Miller, R.D, Ivanov, J., and Corwing, R.F. Condition Assessment of Levees, U.S. Section of the International Boundary and Water Commission. Report 5 Flood Simulation Study of Retamal Levee, Lower Rio Grande Valley, Texas, Using Seismic and Electrical Geophysical Models. Army Corps of Engineers, 2005.Google Scholar
  3. Fraser, D. C., Resistivity mapping with an airborne multicoil electromagnetic system, Geophysics, 43, 1, 1978.ADSCrossRefGoogle Scholar
  4. Fountain, D., Airborne electromagnetic systems—50 years of development. Exploration Geophysics, 29, 1–11, 1998.CrossRefGoogle Scholar
  5. Frischknecht, F.C., 1967, Fields about an oscillating magnetic dipole over a two-layer earth, and application to ground and airborne electromagnetic surveys: Quarterly Colorado School of Mines, 62, 1–326Google Scholar
  6. Grant, F.S. and West, G.S., Interpretation Theory in Applied Geophysics, McGraw-Hill, 1984.Google Scholar
  7. Huang, H. and Fraser, D.C., The differential parameter method of multifrequency airborne resistivity mapping. Geophysics, 61:1, 100–109, 1996.ADSCrossRefGoogle Scholar
  8. Reid, J.E., Worby, A.P., Vrbancich, J. and A.I.S. Munro. Shipborne electromagnetic measurements of Antarctic sea‐ice thickness. Geophysics, 68:5, 1537–1546, 2003.ADSCrossRefGoogle Scholar
  9. Palacky, G.J., The airborne electromagnetic method as a tool of geological mapping, Geophysical Prospecting, 29, 1981.ADSCrossRefGoogle Scholar
  10. Palacky, G. J., Resistivity Characteristics of Geologic Targets. Electromagnetic Methods in Applied Geophysics, Society of Exploration Geophysics, 1988.Google Scholar
  11. Siemon, B. “Electromagnetic methods—frequency domain”, in Groundwater geophysics—a tool for hydrogeology, ed. R. Kirsch, Springer-Verlag, 2006.Google Scholar
  12. Sorensen, J. C., and Chowdhury, K. 2010. Levee Subsurface Investigation Using Geophysics, Geomorphology, and Conventional Investigative Method. Proceedings of 30th Annual USSD Conference, Sacramento, California, April 12–16, 2010.Google Scholar
  13. Spies B.R. 1989. Depth of investigation in electromagnetic sounding methods. Geophysics 54, 872–888.ADSCrossRefGoogle Scholar
  14. Stanley H. Ward, (1967), 2. Part A. Electromagnetic Theory for Geophysical Applications, General Series : 13–196Google Scholar
  15. Ward, S.H. and Hohmann, G.W. 1988, Electromagnetic theory for Geophysical applications, in Nabighian, M. N. Ed., Electromagnetic methods in applied geophysics, Vol. 1: Society of Exploration Geophysics, 131–312.Google Scholar
  16. West, G.F and Macnae, J. Physics of the electromagnetic induction exploration method, in Electromagnetic methods in applied geophysics, Ed.M Nabighian, Society of Exploration Geophysicists, 1991.Google Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.CGGTorontoCanada
  2. 2.Sander GeophysicsOttawaCanada
  3. 3.Engineer Research and Development CenterVicksburgUSA

Personalised recommendations