Social and economic development in most developing countries currently stands as a dilemma between meeting basic human needs of the increasing population on one hand, and conserving declining natural resources on the other. Development projects such as dam, road, power line construction etc. bring about changes in the ecosystem in which they are undertaken. Such changes affect both the environment and well being of man. These impacts can be adverse if the processes are not well regulated or controlled through improved project selection and more responsive planning and design.
In order to mitigate the negative effect of any industrialized projects, there is a need to introduce, environmental impact assessment (EIA) as a tool to charter a new course of development action, which ensures a balance between environmental protection and human development and hence attain the concept called as sustainable development. To ensure sustainable development, the various countries adopted Environmental Impact Assessment (EIA) policies as a basic preventive mechanism and hence protecting the environment as well.
Environmental Impact Assessment (EIA) has developed into a universal tool for planning, and has become mandatory, in some form or another, in all industrialized countries. Changes and development in the infrastructure in the modern society is inevitable and most countries also have legislation to cover for the assessments of the impacts. It is thus very common to do an EIA for all projects over a specified size, given in the national legislation.
It is thus mandatory for developers to deliver an EIA report, which provides a baseline description of the area and the project, and which gives an assessment of the conditions both under the construction phase and the operation phase. It is also the obligation of the developer to try to reduce or eliminate impacts during both phases by changing procedures, design or other factors to mitigate the impacts.
Different authors define EIA in different ways. Some definitions are as
- An environmental impact assessment is a systematic analysis of the potential impacts of proposed development projects on the natural and human environment, for identifying measures to prevent or minimize impacts prior to major decisions being taken and project commitments made.
- An EIA is the impact assessment of proposed project on all type of environment, prior to taking the project under construction. And the project is taking under the construction only when there is no any adverse impact found on the Environment during impact analysis.
- The International Association for Impact Assessment (IAIA) defines an environmental impact assessment as "the process of identifying, predicting, evaluating and mitigating the biophysical, social, and other relevant effects of development proposals prior to major decisions being taken and commitments made”.
- "Identify and predict the impact on the environment and man’s health and well-being of legislative proposals, policies, programmes, projects and operational procedures and to interpret and communicate information about the impact". This is the most fitting definition that given by Munn (1979)