RESAP is normally used to determine equivalent earth structure models based on measured soil resistivity data. These soil models can be used to analyze grounding systems, conduct cathodic protection studies, examine electromagnetic induction (EMI) problems and compute line parameters. RESAP is one of the main component of the AutoGround, MultiGround, AutoGridPro  and  AutoGroundDesign  software packages.

Given the field data, RESAP produces automatically a soil structure which most closely matches the data. In addition, RESAP can generate simplified approximate models with a reduced number of layers as specified by the user.

RESAP calculates equivalent soil models and compares the apparent resistivity produced by the model with the field data.

Technical Highlights

With RESAP, you can develop three fundamental types of soil models:

• Horizontally-Layered Soils - Specify any number of layers.
• Vertically-Layered Soils (Up to 2) - Specify layers oriented arbitrarily with respect to the electrode array used for the measurements.
• Exponentially Varying Soils - Soils having a resistivity which varies exponentially with depth can be useful for computing transmission line parameters or representing frozen soils.

Technical Features

• Generate apparent resistivity curves based on the computed soil model along traverses specified by the user for comparison with the measured data.
• Specify soil resistivity data from Wenner or Schlumberger configurations, or design your own arbitrary traverse spacing arrangement.
• Simultaneously treat data from several field measurement traverses to obtain the best fit model.
• Optionally, specify current probe length, potential probe length or both, for additional accuracy (especially at smaller electrode spacings).
• Use the LOCK feature to have the program calculate a soil model incorporating layer characteristics you specify.
• Choose between a fixed traverse center or a fixed traverse extremity.
• Continuously vary the ratio of current probe spacing to potential probe spacing (a traverse may start as a Wenner configuration and may finish as a Schlumberger configuration).
• Choose between five powerful least-square minimization algorithms (Steepest-Descent, Levenberg-Marquardt, Fletcher-Powel, G-Conjugate, Conjugate Gradients, Simplex ) to perform the optimization process. The default algorithm is based on the extremely stable steepest-descent method.
• Two sets of digital filter coefficients (standard and high-precision) are available to compute apparent soil resistivities.