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There is no doubt that studies using satellite imagery and computer compatible 
tapes will provide operational techniques of analysis. The studies reported 
(Thornburn, 1974) show that each of the four imagery bands may be of use and the 
addition of a thermal band on Landsat 3 wil) significantly extefd the utility oft 
satellite imagery for water pollution detection. Although the definition and 
resolution of problem areas could be improved, it should be recognized that a new 
and powerful tool has been made available. 
It is generally accepted that one of the most advantageous uses of remote sensing 
for environmental quality control is in its application as & surveillance tool to 
detect and identify potential sources of pollution. That is, to provide the 
environmental monitor with information on the proximity of hazardous materials to 
waterways and on the integrity of structures designed to contain these materiels. 
Most studies have found that high quality colour infra-red photography at scales 
between 1/40 ,000 and 1/60 ,000 is most useful for regional surveys and coiour aerial 
photography at scales of 1/5,000 to 1/10,000 is best for detailed local surveys. 
4, Waste Disposal Surveys 
There are many applications of remote sensing in identifying, locating, mapping 
and measuring present and potential tipping sites. Just four examples are quoted 
below of remote sensing applications to various aspects of waste disposal studies. 
1. Standard Black and White Panchromatic Aerial Photographs - aerial photography 
can provide synoptic coverage of individual waste disposal sites or for systematic 
coverage of all waste disposal sites in a particular area. The type of information 
that can be obtained by means of air-photo interpretation includes data on exact 
size and location of waste disposal sites, whether wet or dry, hydrological 
conditions in and around the site (at time of photography), nature of vegetation 
cover (density, type, height etc)., whether the site is in use or disused, above 
or below ground level, area of site, rock type, if any mineral is being extracted, 
nunber of houses, within 1 km or distance to nearest house, number of access points, 
general character of surrounding area etc, The results of such a survey can be 
plotted on transparent overlays to be superimposed on available maps. 
2. Colour Infra-red Photography - by using this fiim type, detailed information 
on any oue site or a particular region can be obtained to examine the effects of 
waste tipping on the surrounding area. The photography can be interpreted in 
terms cf vegetation damage, effects that the toxic wastes may have on the ground- 
water table and/or drainage and hence on the surrounding area, detailed information 
on surface and sub-surface drainage conditions. 
5.. Volumetric Measurements - detailed volumeiric measurements of any waste 
disposal/tipping site can be obtained in order to assess the capacity of a 
particular site or to examine the rate at which a site is being filled, if 
repetitive measurements are taken, contoured plots of the waste disposal site, 
volume computations using punched tape output from photogrammetric plotting 
instruments. 
4, Models - high density polyurethane land form models can be made. These can 
be used for detailed planning of the site and allow monitoring of the changes to 
be displayed. 
5. land Degradation 
In development, activities man often has a profound detrimental effect on the land. 
This type of land degradation is of particular relevance in developing countries, 
where the opening up of natural forests for agriculture and the activities