Thesis title: Numerical Modeling of Electrical Resistivity Tomography (ERT) for groundwater contamination monitoring
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Abstract:

In this work, we present the development of MATLAB based 2-D resistivity inversion algorithm using damped least square method and a comparison of a developed algorithm with the standard resistivity inversion software (i.e. RES2DINV) to check its compatibility. Further, a time-lapse Electrical Resistivity Tomography (ERT) data sets were acquired on the same profile during pre and post-monsoon at IIT Kanpur campus to identify the potential conduit for groundwater recharge First, the forward problem is solved in the Fourier domain where finite difference equations are obtained using area discretization for Poisson’s Equation. It includes an optimization method for the choice of a set of Ky for inverse Fourier transform. Singularity correction is done by separating primary and secondary potential to increase the accuracy near current electrodes. Inversion is carried out using a damped least square method (Marquardt-Levenberg algorithm). The best fit between observed and the calculated apparent resistivity data is attained by using a damping factor of 0.01. The code has been verified for analytical solutions and various benchmark models. And the robustness of the algorithm is showed by a synthetic model computation and then the field data inversion by comparison of results with widely acclaimed RES2DINV software. A satisfactory coherence is seen between them for delineation of the water-bearing formations and estimation of their depth and thickness.

Summary:

• Development of MATLAB based 2D resistivity forward modeling algorithm using a finite-difference method and inverse modeling algorithm using a damped least square approach.
• Acquisition and Interpretation of Time-Lapse ERT data for groundwater Modeling.
• To check the robustness of Algorithm with synthetic model and a Real fielddata.

Link to article:

A MATLAB based program for the Inversion of Time Lapse ERT Data