Groundwater exploration in limestonea??shalea??quartzite terrain through 2D electrical resistivity tomography in Tadipatri, Anantapur district, Andhra Pradesh

摘要

Two-Dimensional (2D) Electrical Resistivity Tomography (ERT) survey was carried out at 11 sites within an area of $10 m{km}^{2}$ to delineate deeper potential groundwater zones in a complex geological terrain underlain by quartzite, shale and limestone formations with varied resistivity characteristics. The area is in medium rainfall zone in Tadipatri mandal of Anantapur district, Andhra Pradesh state, India. The investigation was carried out to meet the growing demands of water supply. Interpretation of the highdensity 2D resistivity dataset results revealed potential zones at only three sites in Tummalapenta, Ayyavaripalle and Guruvanipalle villages within the depth zone of 24a??124 m. A major fault zone orientedin EW direction is mapped at Tummalapenta site. Based on high resolution geophysical data interpretation and significant anomalies, four boreholes were drilled in complex, viz., limestone, shale and quartzite formations up to a maximum depth of 192 m in the area with the yield ranging from $300$ to $sim 5000$ liter per hour (lph). These four anomalous drilled borehole sites corroborates with the aquifer zone delineated through ERT technique. The aquifer parameters estimated from pumping tests show that the transmissivity varies between $sim 0.3$ and $m{179.5 m^{2}/day}$ while the storage coefficient ranges from 0.137 to 0.5 indicating large variation in aquifer characteristics of the system in a smaller area. Suitable water conservation measures were suggested for improving the groundwater condition and yield of the pumping wells.