At any point of time, the environment of a locality is a dynamic entity which represents a set of complex interactions between the atmosphere, hydrophsere, lithosphere and the biosphere. It is always in a state of perpetual change. These changes occur in nature very slowly and seldom result in drastic consequences for the life which flourishes in the system.
However, in early nineteen sixties it was realized that rapid development, spread of agriculture, industralization urbanization and exploitation of resources can result into serious adverse impact on the environment Economic growth and development improve the quality of life but have negative effects on the quality of environment which in long run may affect adversely the very quality of life and the basic purpose of all developmental activities could be defeated. Hence the planning for development must include environmental concerns and a balance has to be achieved between environmental protection and the developmental activities.
The idea of assessment of the possible impact on the environment before starting a development project – such as construction of dams, establishment of industries, land clearance for agriculture or other uses – is an old one. U.S. Army Corps of Engineers had developed techniques and methodology for impact assessment as early as 1870.
However, Environmental Impact Assessment in its present form was introduced with the ‘action forcing provisions’ of U.S. National Environmental Policy Act of 1969. Since 1970, Environmental Assessment systems have been adopted independently by both industrialized as well as underdeveloped countries world wide. Environmental Impact Assessment has now been incorporated in international treaties and conventions as well – such as in Convention on the Environmental Impact Assessment in Transboundary Context and in Annex of the Antarctica Protocol.
Environmental Impact Assessment can be defined as the study of impact on environment of proposed action like policy, plan or project. It is a process of anticipating or establishing the changes in physical, ecological and socio-economic components of the environment before, during and after an impending developmental project so that undesirable effects, if any can be mitigated. Environmental impact assessment has to try to answer the following set of questions:
1. What are the environmental issues associated with the project?
What will be the extend of changes?
3. Whether these changes are significant?
4. Whether the benefits derived from the project are worth the environmental damages sustained?
5. What can be done about adverse impacts?
A developmental activity is under-taken for the benefit of the people of the locality or the State. The Socio-economic quality of life cannot be sustained indefinitely if the activity causes adverse changes in the environment – howsoever, small these changes may be at some point of time in future the entire system could deteriorate. A thorough assessment of the likely impact which a proposed plan or project shall cause, is therefore, essential so that even the minor seemingly insignificant changes are brought to the notice of policy makers.