CASE
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1983, Rock, 1988, Ustin et al 1994, Curtiss et al 1989).The
observation and measurement of the red-edge shift is difficult,
requiring Very high spectral resolution. Differences in wavelength
position between stressed and healthy vegetation range from 0 (no
shift) to 10 nm, but generally are less than 5 nm. ( Singhroy et al
1986). This requires very high resolution field and aircraft
spectrometers. | b5 ,
On the other hand, the chlorophyll concentration is a well defined
parameter that has a direct effect on reflectance spectra. The
absorption band analysis techniques developed for the analysis of
minerals spectra can be used for vegetation. These methods have
been in use for several years for mineralogical analysis. (Kruse et
3,1990, and others). Singhroy and Kruse 1991 reported on the
results of hyperspectral and narrow band multispectral images to
characterize vegetation damage associated with mine tailings. The
image processing techniques used the changes in spectral response
of vegetation in the chlorophyll absorption bands at 680nm.
Several remote sensing case studies on mine tailings have been
reported in Canada. The sensors used include airborne and
spaceborne multispectral images and aerial video. Graham et al.
(1994) used principal component analysis techniques on Landsat
TM images to monitor vegetation changes on large areas affected
by iron ore mining operations at Noranda, Quebec. Mussokowski
(1983) used classification techniques of multidate Landsat TM
data to monitor vegetation change over a ten year period in the
Sudbury. Similar techniques were also used by Hornsby et al. 1989
at the placer gold mining areas in the Yukon. Digitize air
photographs, integrated with topographic and drainage data were
used to characterize gold mining areas in Timmins, Ontario
(Mussokowski et al. 1993). Airborne multispectral techniques are
the most effective to detect and monitor vegetation damage at mine
sites, and have been used successfully by ( Singhroy and Kruse,
1991, King, 1993, and Singhroy 1992).
2. DISCUSSION
2.1 Sudbury Case Study - Environmental Restoration.
The Sudbury mining district in Canada is one of the world
largest metal smelting complexes and is well known as a
polluted region, where the landscape has been devastated.
Mining and processing of nickel and copper has started 100
years ago. Soil and vegetation were lost from tens of thousand
of hectares of land surrounding the smelters. Lakes in the
region were acidified and contaminated with metals. The
damaged area surrounding Sudbury is of sufficient size that
TM imagery provide a convenient means of monitoring
changes in the vegetation. In this area multi-date TM were
used to characterize the extent of vegetation damage and
monitor vegetation successes in the region. A June 1984 and
1995 Landsat images,(Bands 3,4,5) were enhanced and
classified to assess environmental change over the last 11
years. The results have shown (Figures 1(1984) and Figire 2
(1995)) that the areas covered by mine tailings have been
reduced by 40% and vegetation growth has increased by 50%.
This environmental restoration as shown from the analysis of
multi-date Landsat analysis is the result of a well- integrated
multifaceted approach to the development of environmental
control technologies and strategies. As an example of one of
the many strategies, Inco Limited now retains 90% of the
sulphur in the mined ore, which is the reversed of 1960s,
when 90% of the ore ‘s sulphur was emitted to the
ütmosphere as sulphur dioxide.(Gunn 1995)
Airborne multispectral images (CASI) were used to monitor
levegetation success at Inco's Copper Cliff tailings area. The
tailings area is the largest is the largest repository of reactive
tailings in Canada. It covers approximately 5500 acres and
contain more than 10% of all tailings in Canada. Tailings have
been deposited in the basin since the 1930’s, and future
613
deposition has been designed for more than 30 years. Results
have shown that the enhanced CASI images provided the spatial
and spectral details to assess revegetation success at sites under
rehabilation
Airborne SAR images were used to characterise the surface
roughness and local fractures of the large tailing areas so as to
prevent acid mind drainage.
2.2 Waste drainage at land fill basements.
One of the most important tasks for environmental geological
investigations of land fill areas is the evaluation of their
basement properties. The capability to prevent waste drainage
from migrating into the soil and the ground water table is one
of the main objectives for geological investigations at land fill
areas. In every case the natural basement of a land fill is
covered by waste.
Geophysical methods can penetrate the waste and provide
information on structural features, soil properties or distances
to the ground water table. A combination of geophysics and
the evaluation of historic air photos can contribute to
describing rock properties at the land fill basement.
Despite modern in remote sensing technologies, historic air
photography is an important tool to get high resolution data of
the former land surface that is now covered by the land fill. In
this case a 1945 air photograph provides a detailed view at the
topography of the land fill basement. The photo (shown in oral
presentation) characterizes the property of the natural land fill
basement. The main rock unit of the basement, in this case, it
is a highly rugged limestone. It is covered by clay and loamy
sediments (thickness: 1 to 3 meters). Normally, that rock
would protect the underground against the inflow of waste
drainage coming from the overlaying land fill. In this case,
natural protecting capabilities of the topsoil were disturbed by
creating the building pit. Contaminated water can penetrate
the rugged limestone without any obstacles and migrate
outside by using the natural ground water flow.
This example shows that historic air photos dre effective low
cost method to assess landfill basements.
2.3 Hazardous materials dumped within mine and mill
tailings
Thermal infrared images can detect materials whose
decomposition produces relatively high temperatures
compared to their surroundings. The site is a mine and mill
tailings (shown in presentation). One of the main
environmental problems of the site is being caused by dumped
pyrites and carbon shale. Oxidizing pyrite by produces sulfur.
Contact of the sulfur with rain water produces acid drainage.
The acid drainage has contaminated the ground water at the
site. Therefore, the knowledge about the location of the
oxidizing pyrites is needed to take steps against that process.
The oxidation of the pyrites causes the inflammation of the
carbon shales which produces an increase in temperature. The
temperatures are detectable at the surface, even if the
oxidizing pyrites are covered by thick layers of other material.
In this case, thermal remote sensing is a very prospective tool
for detecting the locations of the pyrites. Thermal anomalies
(shown in oral presentation) indicate the locations of a pyrite
bearing tailings. The average surface temperature outside the
area is about 5°C. The areas characterized by radiation
temperatures >25° correlate with accumulations of pyrites and
carbon shales. Temperatures up to 36,1° could be measured in
some areas.
This example shows that thermal remote sensing has assisted
in the detection of serious risks for the soil and the
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996
