Even if airborne geophysical methods have been used for decades in oil exploration, it has not yet been the case for drinking water. Available since about 2004, the system currently consists of a hexagon-shaped electromagnetic scanner, about twice the area of a tennis court, suspended from a helicopter flying at a height of 30 to 50 metres.
“The geophysical system from SkyTEM works like a big 3D scanner of the ground using the same physical concepts as an MRI scanner at hospitals,” explains Per Gisseloe, Project Manager at SkyTEM, which produces these antennae. “The signal we measure depends on the electrical properties in the ground. Water-saturated sand that can be a potential groundwater reservoir will give a higher signal back than dry sand, for example. The electromagnetic field transmitted by the geophysical system does not pose any risk to the public. The field strength is less than that transmitted by an electrical train.”
The studies allow detailed analysis of the composition and geology of the soil and allow the construction of models to manage groundwater. In addition, these analyses provide important information for later deciding where to drill and place wells. But without a doubt, one of their biggest advantages is the time and money saved thanks to helicopter transport, which can cover large areas quickly (up to 1,000 linear km per day in ideal conditions).