Assessing the groundwater potential of the crystalline basement in the Greater Guwahati area, Assam, northeastern India, through the integration of lineament mapping and exploratory drilling

The depletion of groundwater resources and increasing per-capita demand have transformed groundwater into a high-value asset globally. India, the largest user of groundwater in the world, is expected to further increase its reliance on these resources in the foreseeable future. Decreasing per-capita groundwater availability poses challenges to achieving the United Nations' Sustainable Development Goals (SDGs). To address this issue, extensive groundwater exploration is necessary to ensure the SDGs can be achieved. The present study, conducted in the crystalline basement of the Greater Guwahati area, Assam, India, focused on identifying groundwater potential zones through lineament mapping and validating these zones with exploratory drilling. Band 3 sub-scene of the IRS-P6 LISS III satellite images were processed for lineament analysis. Based on statistical analysis, the identified lineament directions were grouped into directional sets which were then compared with regional stress patterns and verified through field investigations. This correlation indicated the groundwater potential within each fracture group. A follow-up exploratory drilling program revealed the presence of several water-bearing zones within the crystalline formation, with the most productive fracture horizons found at depths between 80 and 125 m below ground level. Statistical relationships among fracture depth, transmissivity, specific capacity, and yield factor were examined and correlated. The results showed a gradual decrease in well yield with increasing depth, with yields becoming very low beyond 200 m. Additionally, a strong linear relationship (r² = 0.82) was observed between lineament density and the average yield of drilled boreholes in the study area.