5.1.3. Forward Modeling

Here, the code dcipoctree_fwd.exe and the input file dcip_fwd.inp (see format) are used to forward model DC and IP data along 9 pole-dipole profile lines oriented West to East. Files relevant to this part of the example are in the sub-folder fwd. For this example, we use the models that were created in the example “create model”. Before running this example, you may want to do the following:

• Download and open the zip folder containing the entire DCIP octree example (if not done already)

• Learn how to run code from command line

• Learn the format of the input file

To forward model the data, the following input file was used. Because the survey file (survey_xy.loc ) uses a surface format, any electrodes located in air cells are automatically projected to the discrete surface topography defined by the active cells model.

By choosing the IPL flag on the first line of the input file, we are modeling DC and IP data. And a linearized formulation for modeling the IP data is used. The DC data are the measured voltage normalized by the transmitter current (V/A). The code also outputs the corresponding apparent resistivity values. The IP data are the IP voltage normalized by the DC voltage (V/V). Below, we show the 2D pseudo-sections for data collected along profile line 5 (Northing = 0 m).

Voltage Data (V/V)

Apparent Resistivity (Ohm m)

Apparent Chargeability (V/V)