Airborne Geophysical Services > Applications > Environmental

Introduction

Environmental monitoring is a relatively new application of airborne geophysics, requiring precise measurement of the geophysical parameters (conductivity, etc.), and high resolution of anomaly size and depth. While EM is used most often for mapping groundwater location and salinity, magnetic surveys have been used to detect buried metallic objects and pipelines, and gamma ray spectroscopy can be used to detect man-made radioactivity.

Saline Water Mapping

The presence of saline water on land, whether ground water or intruding sea water, can be very destructive to natural and agricultural plant life. The high conductivity of such water makes it an excellent target for EM detection.

The Florida Everglades is an example where the high rates of groundwater removal, and the interference with groundwater flow by construction, has led to intrusion of sea water under the land surface, killing the natural vegetation. EM surveys have been used several times to map the limits and depth of the saltwater intrusion, and to document the changes over time.

Saline ground water near the surface is a major environmental hazard in Australia, where large areas of farmland may be ruined by rising saline waters. Airborne EM is being used to map the distribution and depth to the saline water over very large areas, to assist the government in planning control programs.

Brine rising through abandoned oil wells can also contaminate the surface, destroying croplands. Airborne EM surveys have been used in Texas to map the location and source of the more conductive saline water. Simultaneous magnetic surveys served to help pinpoint the buried well casings that may be leaking.

Case Histories Florida Everglades (PDF 3.7 Mb), West Texas Brine (PDF 1.58 Mb), Paleochannels (PDF, 176 Kb)

Site Characterization

Significant environmental risk has been created by the run-off or leakage of acidic water from mines and tailings ponds. Airborne EM has been used in Canada, Australia, and the United States to detect and delineate this drainage, both on surface and through bedrock. Surveys have located leaks in tailings dams and drainage to surface from abandoned coal mines, as well as drainage through deep structures under a lake - undetectable by surface sampling.    

Case Histories Site Characterization (PDF, 1.39 Mb), Tailings Pond , Characterization of an Industrial Site in the Canadian Arctic (PDF, 624 Kb) , Contaminant Mapping (PDF, 291 Kb)