Abstract
Laboratory-scale experiments were conducted to investigate the response of electrical potential difference distribution to conductive-body geometry using the Mise à la Masse (MALM) method. Characterizing subsurface conductive pathways is important for understanding groundwater systems, particularly in areas where underground rivers may serve as water resources. However, the heterogeneous nature of natural subsurface conditions requires controlled laboratory experiments to understand the basic MALM response. Two conductor geometries, straight and two-branch models, were tested in relatively homogeneous dry and wet sand media. Potential differences were measured at observation points around the models and visualized as contour maps. The results show distinct potential distribution patterns associated with medium conditions and conductor geometry. Wet-sand models produced more continuous and relatively smoother potential distributions, making the conductive-body geometry more readily recognizable than in dry sand. The two-branch conductor generated a more complex potential pattern than the straight conductor, indicating that conductor geometry influences the surrounding potential field. These results demonstrate the capability of MALM to characterize conductive-body responses under controlled laboratory conditions and its potential for delineating underground river pathways. Further experiments using heterogeneous media and more realistic subsurface conditions are needed to evaluate its field applicability.