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.