Gamma-ray remote sensing

Gamma-ray remote sensing (gamma-radiometrics) measures natural low-level radioactivity from the top 35-50 cm of the Earth's surface, although deeper profiles may be inferred from this layer. Image maps of gamma-ray emitting elements may define soil types as well as physical and chemical processes. Image features of these processes can be used to define and mitigate environmental problems - see following examples:

Mapping salt-source areas in the Murray-Darling Basin

Areas of salt source materials, namely aeolian soils derived from a massive ancient salt-lake, are modeled from a regional gamma-ray image mosaic. Evidence for the validity of the model is found from salinity measured in deep boreholes. Further supporting evidence is the close correlation of salt-sources mapped by gamma-ray signatures and saline areas mapped by local Airborne Electro-Magnetic (AEM) surveys.

Read More: Bierwirth, P.N., and Brodie, R.S., 2006. Developing a salt source model for the Murray-Darling Basin from natural soil-radioactivity and geological data. BRS Report

Also: Bierwirth, P.N., and Brodie, R.S., 2008. Gamma-ray remote sensing of aeolian salt-sources in the Murray-Darling Basin, Australia. Remote Sensing of Environment. Vol 112/2 pp 550-559.

Bierwirth, P.N., 2008. Gamma-ray remote sensing of salt-source materials in the Murray-Darling Basin. 14th Australasian Remote Sensing and Photogrammetry Conference, Darwin (Paper) (Presentation)

Bierwirth, P.N.,2006. Defining sources and stores of salt at Billabong Ck, N.S.W, using airborne gamma-radiometric and electro-magnetic data. BRS Report

Detecting Acid-Sulfate Soils Hotspots

Acid sulfate soils are a major environmental problem, being commonly found in coastal areas, and when disturbed produce acid at toxic levels. This chemical process produces a distinctive gamma-ray signature.

Read More: Bierwirth, P.N., and Brodie, R.S., 2005. Identifying acid sulfate soil hotspots from airborne gamma radiometric data & GIS analysis. BRS Report

Soil Mapping in a forested area:

Bierwirth, P.N., Aspin, S.J, Ryan, P. J., and McKenzie, N. J. (1998). Gamma-ray remote sensing of soil properties in a forested area near Batlow, NSW. Proceedings of the Ninth Australasian Remote Sensing Conference.

How strongly does vegetation block gamma-ray emissions from soils and rocks?

Dense vegetation can reduced airborne-detected gamma-rays by between 13 and 22%.

Read More: Aspin, S.J., Bierwirth, P.N.(1997). GIS analysis of the effects of forest biomass on gamma-radiometric images. Proceedings of the Third National Forum on GIS in the Geosciences. AGSO Record1997/36. .

Gamma-ray remote sensing of soil properties near Wagga Wagga, NSW

Bierwirth,P.N,. Gessler,P. and McKane, D. (1996) Empirical investigation of airborne gamma-ray images as an indicator of soil properties - Wagga Wagga, NSW. 8th Australasian Remote Sensing Conference Proceedings. Canberra.

Investigation of airborne gamma-ray images as a rapid mapping tool for soil and land degradation - Wagga Wagga,NSW, AGSO Record 1996/22.

Read More:

Soil Mapping at Proserpine, North Queensland

Bierwirth, P.N., Hardy, S, Wilson, P., Philip, S., Smith, D., Heiner, I. and Grundy, M. (1997). Radio Ga Ga - Integrating gamma-radiometrics into landscape modeling of soil attributes; results of an ACLEP exchange. ACLEP Newsletter , vol 6, no 4, December, 1997

Free Gamma Farm Images

This service provides gamma-radiometrics images to farmers within the region defined by the Murray-Darling Basin. Large sections of the basin have been flown with higher resolution airborne spectrometry which measures the minor concentrations of radioactive elements (potassium, thorium, uranium) in soils. The concentrations of these elements are commonly associated with soil types and properties. The images, created from combining Google Earth electro-optical imagery with gamma-radiometrics, can be used to assist in farm management.

See example imagery

To order imagery, please email the consultant at to provide location information.