## 4 Discussions  
The use of ERT has been particularly effective in monitoring changes in contaminant plumes over time, as demonstrated in studies by [PERSON] et al. [36] and [PERSON] et al. [37]. These methods offer high-resolution images of subsurface structures, enabling the identification of contaminant distribution and migration pathways. In this study, we meticulously examined how lens bodies influence the migration characteristics of light non-aqueous phase liquids (LNAPLs) using two-dimensional indoor sandbox simulations coupled with high-density resistivity imaging. Our findings reveal that lens bodies notably affect LNAPL migration patterns within the vadose zone, with high-permeability lens bodies facilitating vertical LNAPL migration and low-permeability lens bodies impeding this movement, thereby enhancing horizontal spread. These insights are crucial for environmental management, offering a framework for predicting LNAPL behavior in heterogeneous subsurface environments and guiding the development of targeted remediation strategies. Notably, areas with high-permeability lens bodies may require intensified monitoring due to their potential to facilitate rapid LNAPL migration. Furthermore, our results corroborate previous studies by demonstrating that LNAPL significantly alters subsurface resistivity, consistent with its inherently high resistivity. For instance, studies by [PERSON] et al. [38] and [PERSON] et al. [39] have documented changes in soil resistivity due to petroleum contamination, which is in line with our observations of resistivity changes in response to LNAPL migration. Our study on the migration of light non-aqueous phase liquids (LNAPLs) in the vadose zone, particularly in the presence of lens-shaped bodies, contributes to the ongoing discourse on subsurface contamination and its remediation. By integrating high-density resistivity imaging with sandbox experiments, we have provided a detailed analysis that supports and expands upon previous research in the field. [PERSON] et al. [38] conducted a spatial analysis of a polluted site, emphasizing the importance of joint conceptual modeling in understanding contamination dynamics. Our work aligns with their approach by providing a detailed, site-specific analysis of LNAPL migration, which is crucial for developing effective remediation strategies. The significance of hydrogeophysics in enhancing our understanding of subsurface processes, as highlighted by [PERSON] et al., is evident in our study's use of resistivity imaging. This non-invasive technique allows for a better characterization of subsurface contamination. [PERSON] et al. [40] demonstrated the potential of geophysical signals in characterizing contaminated sites, a concept further developed in our research  
Figure 9: Rate of change of resistance (high-permeability lens). (**a**) 60 min (**b**) 100 min (**c**) 200 min (**d**) 300 min (**e**) 400 min (**f**) 490 min. through the analysis of resistivity changes in response to LNAPL migration. This non-invasive approach provides valuable insights into subsurface contamination without the need for intrusive sampling methods. The review by [PERSON] et al. [41] on remediation of soil and water contaminated with petroleum hydrocarbons offers a comprehensive overview of available methods. Our study's focus on the migration characteristics of LNAPLs provides fundamental data that can guide the selection and application of these remediation techniques. In discussing the implications of our findings, we must consider the broader context of environmental remediation. The work by [PERSON] et al. [37] on enhanced LNAPL remediation provides a compelling case for integrating hydrogeophysical findings with chemical evidence. Our study's results support this approach by demonstrating how the presence of lens-shaped bodies affects LNAPL migration, a factor that must be considered in any remediation effort. Furthermore, our research underscores the importance of understanding the complex interactions between LNAPLs and subsurface structures.