The Ground Conductivity Meter (GCM) inversion module features full non-linear 1D inversion for frequency domain electromagnetic data measured with fixed dual coil systems like the widely used EM31/38, DualEM or similar systems. The module is optimized to handle large amounts of data and is designed specially for data collected for land management in the agriculture industry. The module has many of the same features as the HEM inversion module.

Main features

• A easy-to-use data importer based on straight ascii files.
• Simple inversion greatly improving results as compared to apparent resistivities straight from the instrument.
• Comprehensive visualization features enabling detailed evaluation of the inverted data.
• Integrated with the Aarhus Workbench environment making it fast to produce thematic maps like average conductivities in depth intervals or cross sections form the inverted models.
• Integrated with GIS and data management for handling of very large datasets.

Why invert the conductivity data?

The conductivities measured with the GCM devices are assumed to be in the low frequency approximation. Unfortunately this is often not true for the ground conductivities measured with the devices. The error is not stationary i.e. if the field is dry in one part and wet in another part the error is not the same for the two parts. By inverting the data this error is accounted for and true conductivities/resistivities of the ground are obtained.

Typically the profiles are measured with two devices where one device measures horizontal fields and the other measures vertical fields. For such a system it is possible to obtain depth information by assuming that the ground consists of two layers where the boundaries between the layers are fixed. The output from such an inversion is then two maps; one map showing the conductivity from the surface down to e.g. 0.50 m and one map showing the conductivity from 0.5 m and down.

More Information

For more information about the features in the GCM inversion module contact This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Get the paper High-resolution geophysical characterization of shallow-water wetlands (pdf).