Discuss environmental impact assessment methodologies ?

Ans.The impact identification and assessment can be made through several ways.Each one represents a methodology. Besides the one already explained, there are six other different methodologies in the literature based on the way the impacts are identified and assessed. A critical overview of the methodologies is given below

1. Ad Hoc: These methodologies provide a minimum guidance for impact assessment. They merely suggest broad areas of possible impacts (e.g.,impacts on lakes, forests, etc.,) rather than defining specific parameters to be investigated. This is given exogenously to the analyst.

2. Overlays: These methodologies depend upon a set of maps on the environmental characteristics (physical, social, ecological, and aesthetic) of the proposed project’s vicinity. These maps are overlaid to produce a composite characterization of the regional environment. Noting the impacted environmental attributes within the project boundaries then identifies impacts.

3. Checklists: The methodologies present a specific list of environmental attributes to be investigated for possible. They need not necessarily attempt to establish the cause-effect links to project activities. They may or may not include guidelines about how attribute data are to be measured and interpreted.

4. Matrices: These methodologies incorporate a list of project activities with a checklist of potentially impacted environmental attributes. Then, the two lists are related in a matrix form, which identifies the cause-effect relationships between specific activities and impacts. The matrix methodologies may either

specify which actions affect, which attributes, or may simply list the range of project activities and environmental attributes in an open matrix to be completed by the analyst.

5. Network: These methodologies work from a list of project activities to establish cause-condition-effect relationships. It is generally felt that a series of impacts may be triggered by a project action. They define a set of possible networks and allow the user to identify impacts by selecting and tracing out the appropriate project actions.

6. Combination Computer-aided: These methodologies use a combination of matrices, networks, analytical models, and a computer-aided systematic approach. Since this is a combination of difficult methodologies, it is a multiple-objective approach to; (a) identify activities associated with the governmental policies and programmes; (b) identity potential environmental impacts at different levels; (c) provide guidance for abatement and mitigation techniques; (d) provide analytical models to establish cause-effect relationships and to quantitatively determine potential environmental impacts, and (e) provide a methodology and a procedure to utilize this comprehensive information in decision-making.