Assessment of geophysical methods for groundwater exploration in agricultural communities

Thesis Abstract

Groundwater is a critical resource for agricultural communities, particularly in regions facing water scarcity and irregular rainfall patterns. Despite its importance, the subsurface exploration for sustainable groundwater sourcing remains a challenge due to heterogeneous geology and limited access to accurate and cost-effective detection methods. This study aims to evaluate and compare the effectiveness of various geophysical techniques—namely Vertical Electrical Sounding (VES), Magnetic Resonance Sounding (MRS), Ground Penetrating Radar (GPR), and seismic refraction—in determining the most suitable method for groundwater exploration within rural agricultural settings. The specific objectives include assessing the depth and yield estimates obtained from each method, analyzing their spatial resolution and accuracy, and developing an integrated geophysical approach to improve groundwater prospectivity mapping in the study area. The research adopted a quantitative, comparative case study design within the agricultural communities of Greenfield County, where 50 borehole sites with confirmed groundwater yield data served as the primary population. Stratified random sampling was employed to select 20 survey points representative of varying geological conditions. Data collection involved deploying the four geophysical techniques across the selected sites, following standardized field protocols to ensure data quality and comparability. The geophysical survey results were processed using specialized software, such as IPI2Win for VES data, MRS data processing tools, GPR visualizations, and seismic refraction analysis through SeisImager. Ground truthing was validated via borehole yield measurements, while statistical analyses—including analysis of variance (ANOVA), regression modeling, and receiver operating characteristic (ROC) curve analysis—were used to evaluate the performance and accuracy of each technique. Expected findings suggest that VES provides reliable depth estimates in areas with well-defined resistivity contrasts, whereas MRS offers higher precision in delineating aquifer boundaries, particularly in deep basement terrains. GPR is anticipated to excel in shallow aquifer detection due to its high resolution but may be limited by clay-rich soils, while seismic refraction is expected to contribute to understanding the stratigraphy and identifying consolidated aquifers. An integrated geophysical model combining these techniques is projected to significantly enhance the accuracy of groundwater prospectivity mapping in heterogeneous geological settings. This research contributes to knowledge by systematically comparing the efficacy of multiple geophysical methods tailored for agricultural contexts, leading to the development of a decision-making framework for practitioners. The findings will inform sustainable groundwater management practices by enabling more accurate site selection, reducing drilling costs, and minimizing environmental impacts. The study concludes that an integrated approach leveraging the strengths of each geophysical method offers optimal results for groundwater exploration in agricultural communities where resource limitations and geological complexity pose challenges. Recommendations include adopting a multi-method survey protocol in future groundwater assessment projects, training practitioners in the interpretation of integrated geophysical data, and further research into the development of cost-effective hybrid models incorporating remote sensing data. Overall, this study advances the field of applied geophysics by providing empirical evidence for method optimization in groundwater exploration, fostering sustainable water resource development in rural agricultural environments.