Airborne Geophysics: Fast-tracking Exploration of Mineral and Groundwater Resources in India

Airborne Geophysics is an important branch of Geosciences in which geophysical sensors are installed on a flying machine and flown over large areas to explore the earth’s subsurface, tectonics and natural resources in a fast and cost-effective manner. Considering the significance of this technique in fast exploration of minerals, hydrocarbons, and other natural resources, CSIR-NGRI initiated Airborne Geophysics project in 1966, within five years of creation of the Institute.


In the very first year, CSIR-NGRI carried out first experimental Aeromagnetic survey over the Kudremukha - Kotebare Iron ore belt of Karnataka using Dakota DC-3 aircraft and proton precession magnetometer, followed by another Aeromagnetic survey over Chitradurga Copper belt. The efforts in the first decade were also made for development of Multi-sensor Airborne system comprising of Magnetic, Electromagnetic (EM) and Radiometric sensors. An important contribution came in the form of development of an indigenous Pulse Transient EM system (PTEM) by CSIR-NGRI.


In the past over five decades, CSIR-NGRI has made significant contributions in the field of Airborne Geophysics by keeping abreast with the technological advancements as well as by their effective implementation for socio-economic benefit of the country.


CSIR-NGRI has successfully conducted about 4 lakh line-km (LKM) of airborne geophysical survey in different parts of the county.

  • Airborne magnetic surveys for Geological mapping in India (> 70,000 LKM) and Antarctica (3,500 LKM), and for Hydrocarbon exploration (~31,800 LKM)
  • Airborne magnetic and radiometric surveys for mineral exploration (> 60,000 LKM) and diamond exploration (~38,600 LKM)
  • Airborne magnetic and EM surveys for base metals (~12,000 LKM)
  • Airborne gravity & magnetic and gravity gradiometry survey for Koyna intraplate seismic zone (5,012 LKM)
  • Heliborne VTEM, magnetic and radiometric surveys for uranium exploration (~1,52,000 LKM)
  • Heliborne VTEM and magnetic survey for mapping of deformation in the Himalayan Frontal belt (~900 LKM)
  • Heliborne SkyTEM and magnetic surveys for groundwater and paleochannel mapping (~23,000 LKM)
  • Heliborne SkyTEM and magnetic survey for rail tunnel project (~1,700 LKM)

Applications

The airborne geophysical survey has been used for regional mapping, diamond and base metal and uranium explorations. It has also been used for the following:

Groundwater exploration and paleochannel mapping: Application of Heliborne Transient EM (H-TEM) technique for groundwater exploration in the country was initiated for the first time in 2012 by CSIR-NGRI. A pilot project during 2012-15 covered six hydro-geologically diverse terrains in India to test the efficacy of this advanced geophysical technique. It helped in delineation of fracture network in granitic terrain, sub-basalt aquifers, paleo-channels in alluvial Ganga plains, and sea-water intrusion in coastal regions. Success led to more concerted efforts in the past six years for regional aquifer mapping. This yielded identification of a 45 km long buried paleochannel between the Ganga and the Yamuna rivers near Prayagraj (Stakeholder: CGWB).



The H-TEM technique has been successfully applied subsequently for augmentation of ensured drinking water supply through identification of suitable French well location sites. This technological intervention has been recognized by FICCI Award for science innovation for water security. (Stakeholder: Surat Municipal Corporation)


The success of the H-TEM technique has led to a collaborative project between CSIR-NGRI and Ministry of Jal Shakti (MoJS) through CGWB for groundwater exploration in NW India. (Stakeholder: MoJS & CGWB)



Infrastructure projects in mountainous regions: Recently, CSIR-NGRI has embarked upon a new application of the H-TEM in the country for identification of weak zones along tunnel alignments in mountainous regions. Under this, a project has been executed for the Rishikesh – Karnaprayag tunnel alignment to facilitate safe tunneling. (Stakeholder: Rail Vikas Nigam Ltd. (RVNL))


There are some other tunnel projects under execution stage. (Stakeholders: Konkan Railway Corporation Limited; Altinok India Pvt. Ltd.)








Team Airborne Geophysics
CSIR-National Geophysical Research Institute