Development and validation of a low-cost electrical resistivity tomographer for soil process monitoring

Abstract

This paper presents the development and validation of a low-cost electrical resistivity tomography (ERT) system for the monitoring of process in soils. The ERT technique is capable of evaluating the distribution of electrical properties within a cross section of soil specimens by measuring the applied electrical current and monitoring the voltage distribution along boundary electrodes. This new ERT system consists of (i) a two-dimensional (2D) acrylic testing cell with strip copper electrodes, (ii) an acquisition system and control software, and (iii) a third-party reconstruction software. The tomographer is developed to collect low-noise data at moderate acquisition speeds. To validate the quality of the proposed ERT system, noise levels were evaluated with and without the testing cell and imaging tests were conducted to calibrate the system, evaluate the sensitivity of the instrument to locate a low-resistivity inclusion, and to monitor chemical diffusion in a saturated Ottawa sand specimen. Results show that the proposed low-noise, low-cost ERT acquisition system can be successfully used, with proper interpretation, to locate inclusions and obtain images of diffusion processes in soils. These validation tests show the applicability of the developed acquisition system in monitoring time-dependent processes that do not require real-time acquisition and reconstruction.