SALTMAP — Airborne EM for the Environment

Environmental geophysics mapping salinity and water resources

“…A perfect match is not possible, because the 150 m radius footprint of the AEM system encompasses much more inherent variation than the 1 m radius footprint of the EM39 instrument, but r 2 was improved to 0.33-0.47 for the 0-5 and 5-10 m slices, rising to 0.87 for deeper layers. The significance of these advances cannot be exaggerated; earlier applications of AEM to salt mapping (Duncan et al, 1993) met with scepticism because of the imprecision and inaccuracy of the vertical dimension, especially in the near-surface layer; now, a detailed, accurate, three-dimensional picture of conductivity may be had at a cost of a US$ a hectare. Conductivity may be expressed in terms of salt load, either using pore fluid from undisturbed samples or a water extract such as EC 1:5 .…”

Sandur, sandr

“…This mobile system allows EC measurements to be taken while the operator drives across the field. A new cost effective airborne electromagnetic system, known as SALTMAP, specifically designed for soil and ground water salinity monitoring has recently been developed Duncan et al, 1992). By using these techniques, it is possible to define areas at risk of becoming saline.…”

Reprocessing strategy to obtain quantitative early time data from historic VTEM surveys

“…An established processing strategy to correct for system imperfections such as bandwidth limitation is to deconvolve measured responses in frequency domain to get an ideal response. This approach usually requires a streamed current monitor and streamed receiver data, and was first proposed by (Annan 1986) for the prototype Prospect AEM system, and implemented in the fixed-wing Spectrem (Leggatt 1996), Saltmap (Duncan et al 1992) and Tempest (Lane et al 1998) systems.…”