associated with urban, industrial and highway constructions may all result in 
increased erosion, degeneration of the vegetation, an increase in sediment in 
waterways etc. These effects may, in turn, have further serious consequences 
on the quality of man's environment. 
  
In the construction of dams the following adverse effects can be monitored using 
remote sensing techniques :- air and land pollution caused by increased émounts 
of dust in the eavironment and the destructive nature of the building programme, 
loss of land resource types, loss of particular vegetation associations and the 
increased occurrence of landslides and slumps on the surrounding slopes. On the 
beneficial side the most important aspect is the availability of a contrelled 
water supply for various uses. The effects can he studied using airborne methods 
to show any changes in agricultural factors through the use of irrigation 
techniques. Other essential information required by engineers for determining 
geo-chemical aspects of the dam's construction, which are readily obtained include 
the geology cf ihe area, indications of the amount of sediment likely to be brought 
into the dam by rivers and run-off and the agricultural potential of the land 
downstream. 
In forest management the advantages and disadvantages of various degrees of felling 
in terms of possible degradation of the environment versus increased job opportunity 
and revenue input into the area are important aspects to be considered in 
determining the optimum felling rate in order to sustain employment, wood 
production and financial benefits without the associated adverse effects. The 
factors that can be monitored by remote sensing include environmental degradation 
both from increased run-off and soil erosion, when severe deforestation occurs and 
the possible detection of pollution from pesticides under intense management schemes. 
However, when forests are not managed deterioration in the health of the trees 
through pest attacks and age can be detected. 
These two examples illustrate the delicate balance that must be maintained within 
the environment. The use of remote sensing provides a method whereby sequentiai 
monitoring may aid in understanding the particular limits of the region under 
development, in order to prevent any land degradation. 
6. Summary 
The collection of data necessary to establish a baseline of environmental guality, 
as well as studies to determine the extent of the impact from existing development 
has to date usually been carried oul by means of laborious, time consuming and 
hence costly field investigations. Remote sensing technology can provide a more 
efficient, systematic and less expensive approach to environmental data coliection 
and field survey planning. A series of steps and procedures are outlined below 
and used as guidelines to indicate how remote sensing can be used to accomplish 
any of the following types of objectives in the field of environmental quality 
assessment. 
( i) collect data for land use mapping 
( ii) detect alien substances in the environment 
(iii) identify specific pollutants and classes of pollutants 
( iv) monitor the source, movement and fate of pollutants 
( v) determine the effecus of pollutants on the environment and 
( vi) analyse remotely sensed data to determine environmental 
quality, the susceptibility of the environment to 
degradation and provide data for comprehensive environmenta! 
management planning.