Rapid 3D geophysical imaging of aquifers in diverse hydrogeological settings

Aquifers, major source of fresh water, are depleting in the several parts of the world and posing a threat for a long-term water availability. Managed Aquifer Recharge is one of the potential options to meet the challenge of water security and comprehensive characterization of aquifer system is its essential prerequisite. Aquifer system from soil to the deep aquifers, down to the depth of 200 m or more can be mapped now through advanced geophysical technologies, specially, by airborne transient electromagnetic method. This paper presents a brief description of aquifer characterization through Heliborne Transient Electromagnetic (HTEM) surveys in diverse hydrogeological settings comprising of crystalline hard rocks, sediments, basalts, and alluvium in India. The HTEM results from different geological terrains are compared with ground-based observations as well as with drilling logs to evaluate the efficacy of HTEM surveys. It is found that HTEM surveys rapidly provided 3D geometrical and electrical attributes of aquifers, which compare well with in-situ observations. The high resolution 3D information of hydrogeological settings can be appropriately utilized for sustainable management of groundwater resources by the stake holders, government departments and policy makers.