Joining hydrogeological and geophysical data in an integrated assessment of the groundwater potential in Granitic Aquifer

India’s green revolution during the seventies has led to a complete inversion of the irrigation scenario, with groundwater now sustaining almost 60% of irrigated land. In addition to this, water demand by increasing population for diverse purposes like domestic, industrial, hydropower etc. has put additional stress on groundwater ressources (GWR) and hence resulting in its over-exploitation. Thus, an urgent need has arisen to assess, manage and develop the GWR for future use. Present study deals with the assessment of groundwater resources at Maheshwaram watershed, a granitic hard rock terrain of Archean age falling in the semi-arid condition. Integrated study is comprised of water level, vertical electrical sounding (VES), Electrical resistivity tomography (ERT), magnetic resonance sounding (MRS). The weathered materials are the principal aquifer system and ground water occurs under water table condition. Weathered zone is followed by it’s underneath weathered-fractured zone, where groundwater is found unconfined to semi-confined conditions. Beneath the weathered horizon, fractures system within the basement surface is also supposed to be potential aquifer zone. But determination of fracture geometry is difficult task and these fracture zones have not been fully exploited. It has been established that aquifer geometry of the unconfined aquifer system is important parameters in understanding the aquifer groundwater productivity.
Electrical resistivity and water level studies have helped to classify the lithological setup of the area, whereas MRS has yielded the water content with depths. The results are found corroborating with each other. The integrated analysis has helped in assessing the total groundwater resources. The water content in the area is found varying in the range of 0-8% down to the depth 25 m below ground level (bgl). Maximum percentage of water content is found at arround 15 m (bgl). Integration of the hydrogeological and geophysical results helped in assessing the groundwater potentiality of granite aquifer at Maheshwaram watershed.