Incorporating topographic variations on electrical resistance tomography

Abstract

Electrical resistance tomography (ERT) provides images of the electrical properties of subsurface materials leading to the distinction of different Earth’s interior structures. The accuracy of electrical resistance imaging is strongly affected by the topographical variations so that the lack of incorporation of topography information into the inversion process may produce erroneous anomalies in the resistivity section. Owing to the significance of the topography effects on the resistivity measurements, we use a Schwarz-Christoffel transformation approach to incorporate the irregular surface into the 2.5-dimensional forward solution in the framework of the finite difference method. This approach is implemented on synthetic cases to illustrate how the resistivity measurements are dependent on the topographic irregularities. Numerical experiments demonstrate that in the presence of topographic features between current and potential electrodes, the resistivity response does not reflect the realistic resistivity values of the subsurface even in the case of a homogeneous resistivity distribution.

Keywords

• electrical resistance tomography
• finite difference
• forward modelling
• schwarz-christoffel transformation
• topography