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Scaw Metals Group Annual Report 2005
Scaw Metals Group Sustainable Development Report 2005
39
6
environment case studies
Hyperspectral Images
The remote sensing component of the Rietfontein remediation
project, which is complementing the ground based
monitoring of the project, has been completed. The project
was a collaboration between the Witwatersrand University
(Johannesburg, South Africa), Tel Aviv University (Tel Aviv,
Israel) and Bar-Kal Systems Engineering Ltd (Israel).
Rietfontein Area B
Landfill
The hyperspectral images provide an indication of healthy
plant growth, the presence of certain types of pollutants
and leachate generation. At a glance the hyperspectral
images will be able to illustrate the effectiveness of the
ecological engineering approach used to remediate the
Rietfontein Area B Landfill.
Hyperspectral Remote Sensing Thematic Images were used
as a method of monitoring the presence of vegetation and
mineral contamination on site. The aerial survey was
undertaken at:
47 620 m (resolution: 3 x 3 metre pixels)
43 048 m (resolution: 1.6 x 1.6 metre pixels)
The aerial survey was complemented with soils and mineral
ground truthing. In addition, the NASA Terra Satellite (Aster)
provides the platform for Aster Hyperspectral Remote
Sensing Thematic Images for vegetation and mineral
contamination. This served as the Aster baseline for the
Rietfontein Landfill, in comparison with surrounding footprints
from mining activities. In this context, the presence of
minerals was not detected.
A hyperspectral image of the Rietfontein Landfill site - low
altitude vegetation fraction.
Giant Bullfrog
Since the remediation started on site, two giant bullfrogs
were observed. The giant bullfrog is the second largest
frog in Africa. It buries itself underground only to emerge
after approximately 50mm of rainfall. It stays above ground
for a brief period to feed, after which it again buries itself.
The giant bullfrog is therefore rarely observed. In fact, it
spends most of its 35 to 40 year life span underground.
The giant bullfrog can reach over 20cm in length.
The World Conservation Union has listed the giant bullfrog
as near-threatened in Southern Africa. The information
collected on site will be used to better understand the giant
bullfrog behaviour. Professor Graham Alexander, a zoology
professor at the University of the Witwatersrand, has done
extensive work on the giant bullfrog and will be monitoring
the amphibians in the area.
He may not be much of a size now, but this baby giant bullfrog
grows to over 20cm in length to achieve the status of being
the second largest frog in Africa. Since remediation started on
Rietfontein Area B Landfill, the giant bullfrog has been found
on the site.