UAV-based semi-airborne transient electromagnetic survey in challenging terrain environment

Abstract:

Airborne transient electromagnetic (ATEM) is a versatile tool with applications in mapping underground freshwater, minerals, geological structures etc. This kind of survey usually use a helicopter with transmitting loop and receiver bird hanging dozens of meters under the aircraft. The pilot will have to focus on the terrain-following when acquiring data. However, this will be difficult to implement in very complex terrain environment. We present a semi-airborne transient electromagnetic (SATEM) system. In this configuration, we use Unmanned Aerial Vehicle (UAV) as an aircraft. A receiver coil is hanging several meters under the UAV. The transmitter is put on the ground surface considering the UAV load limitations. We use a galvanic source to induce step current into the earth. The receiver coil will acquire the secondary field in the air. Two obvious advantages are obtained in this UAV-based system: First, all the equipment are far more cheaper than an ATEM system. In addition, the cost of a UAV driver is far more lower than a helicopter pilot. Second, this kind of system will acquire data in a same elevation rather than terrain-following. In this case, we can finish the SATEM survey in those areas with challenging terrain environments. We acquired 63km of SATEM survey lines in a karst development area with complex terrain in Guangxi, China. The resistivity profile show reasonable and interesting results of the subsurface electric distributions.