Monitoring water percolation in a laboratory compacted soil dam using time-lapse electrical resistivity tomography.

Compacted soil dams are critical structures for mining, water supply and power generation, particularly in tropical regions. Monitoring these dams is essential throughout their lifetime, as variations in reservoir water levels due to drought, rainfall or operational changes can significantly affect soil saturation and stability. This study developed a laboratory-scale geoelectrical monitoring system to investigate the dynamics of water percolation and variations in soil saturation in compacted soil dams. Time-lapse electrical resistivity tomography was used to analyze the effects of soil moisture and temperature on electrical resistivity. The results of the electrical resistivity tomography were consistent with the advance of the saturation front, which was observed through photographic records. However, after the saturation front had fully advanced, the direct correlation between surface soil moisture values and electrical resistivity variations was not trivial. This may have been due to the fact that this is a dynamic geotechnical structure, with fluctuations in the dam's internal water level, variations in soil compaction, granulometric distribution and differences in acquisition time between the investigation methodologies. These results underline the importance of continuous monitoring for the early detection of failures and for effective dam management strategies.