meaning, impact analysis:- impact identification and different methods, impact prediction and points to be considered, impact evaluation.

1. EIA Methodologies
PRESENTED BY:
DEEPSHIKHA (809)
MEENAL (827)
RAHUL (835)

2. Meaning
 Methodology means the structural approaches for doing one or more
activities of EIA.
 There are some specific characteristic which an EIA methodology should
depict.
 These are:-
(1)It should be appropriate to the necessary task of EIA process such as
impact identification/comparison of alternatives.
(2)It should be significantly free from assessors bias
(3)It should be economical in terms of costs, and its requirement of data
,investigating time , personnel, equipment and facilities.

3. Impact analysis
 This stage of EIA identifies and predicts the likely Environmental and social
impact of the proposed project and evaluates the significance
 Methods of impact analysis:
• 1. IMPACT IDENTIFICATION
• 2. IMPACT PREDICTION
• 3. IMPACT EVALUATION

4. Impact identification
 Impact Identification attempts to answer the question, “what will happen when a
project enters its operational stage?”
 A List of important impacts such as changes in ambient air quality, changes in water
and soil qualities, noise levels, wildlife habitats, species diversity, social and cultural
systems, employment levels etc may be prepared.
 The important sources of impact like smoke emission, consumption of water,
discharge of effluents etc are identified.
 Methods
• Ad hoc method
• Checklists
• Matrices
• Overlays
• Networks

5. Ad hoc method
 Simple method based on subjective environment impacts on broad aspects.
 Ad hoc method is useful when time constraints and lack of information require
that the EIA must rely exclusively on expert opinion.
 It provides minimal guidance for total impact assessment while suggesting the
broad areas of possible impacts and the general nature of these possible impacts.
 When more scientific methods are available, it is not recommended.
 Types of ad hoc method:
 Opinion polls.
 Experts opinion.
 Delphi methods etc

6.  ADVANTAGE
 Specialists on a particular area will provide guidance.
 DISADVANTAGE
 It require expert.
 Short/long term impact are merely examined on guess basis.
 Identification , prediction and interpretation of impacts are quite poor

7. Checklist method
 Checklist means a listing of potential Environmental Impacts.
 This method is done to assess the nature of the impacts i.e. its type such as
adverse /beneficial , short term or long term , no effect or significant
impact , reversible or irreversible etc.
 Types of checklist method:
 Simple Lists.
 Descriptive Checklists.
 Scaling Checklists.
 Questionnaire Checklists.

8.  ADVANTAGES
 Simple to understand and use.
 Good for site selection and priority setting.
 DISADVANTAGES
 Do not distinguish between direct and indirect impacts.
 Do not link action and impact.
 Sometime it is a cumbersome task.

9. Matrices
 Matrix and its variants provide us a framework of interaction of different
actions /activities of a project with potential EI caused by them.
 A simple interaction matrix is formed where project actions are listed along one
axis i.e. vertically and EI are listed along the other side i.e. horizontally.
 It was pioneer by Leopold et al(1971).
 It lists about 100 project actions and about 88 environmental characteristic and
condition.

10.  ADVANTAGES
 Link action to impact
 Good method for displaying EIA results
 DISADVANTAGES
 Difficult to distinguish direct and indirect impacts
 Significant potential for double-counting of impacts
 Qualitative

11. Network method
 It uses the matrix approach by extending it take into account primary as well the
secondary impacts.
 Shown in the form of tree called as Relevance/Impact tree/Sequence diagram.
 Identification of direct ,indirect /short and long term environment impact is a
crucial and intact basic step of making Impact tree.
 Used to identify cause-effect linkages
 Visual description of linkages

12.  ADVANTAGES
 Link action to impact
 Useful in simplified form in checking for second order impacts
 Handles direct and indirect impacts
 DISADVANTAGES
 Can become overly complex if used beyond simplified version
 Qualitative

13. Overlays:- Mc Harg(1968,69)
 Rely on a set of maps of a project area’s environmental
characteristics covering physical , social, ecological, aesthetic
aspects.
 Separate mapping of critical environmental features at the same
scale as project's site plan e.g. wetlands, steep slopes, soils,
floodplains, bedrock outcrops, wildlife habitats, vegetative
communities, and cultural resources...
 Older Technique: environmental features are mapped on
transparent plastic in different colors.
 Newer Technique: Geographic Information Systems (GIS).

14.  ADVANTAGES
 Easy to understand and use
 Good display method
 Good for site selection setting
 DISADVANTAGE
 Address only direct impacts
 Do not address impact duration or probability

15. Impact prediction
 The accumulated knowledge of the findings of the environmental
investigations form the basis for the prediction of impacts.
 Once a potential impact has been determined during scoping process ,it is
necessary to identify which project activity will cause impact , and its
magnitude and extent.
 Methods of impact prediction:
 Best estimate professional judgement .
 Quantitative mathematical models .
 Experiments and physical models .
 Case studies as analogues or references .

16. Points to consider for impact
prediction
1. Baseline condition
2. Un certainty
3. Spatial limits
4. Temporary boundaries
5. Incremental condition
6. Quantitative and Qualitative methods

17. Impact evaluation
 Its purpose is to assign relative significance to predicted impacts associated with
the projects and to determine the order in which impacts are to be avoided ,
mitigated or compensated.
 Criteria for evaluating potential effects:
 Importance of affected resource
 Magnitude and extent of disturbance
 Duration and frequency
 Risk/likelihood of occurrence
 Reversibility
 Contribution to cumulative impacts

18. Evaluation of EIA system effectiveness
 Be considered effective if
 Information generated in the EIA contributed to decision making.
 Predictions were accurate
 Proposed mitigatory and compensatory measure achieved approved management
objectives
 Efficiency criteria are satisfied if
 EIA decisions are timely relative to economic and other factors determine project
decisions
 Costs of conducting EIA can be determined and are reasonable.

19. Process for evaluation of cumulative
effects
 The area in which the effects of the proposed action will occur
 The impacts that are expected in that area from the proposed action
 Other past, present, and reasonably foreseeable actions that have or are
expected to have impacts in the area
 The impacts or expected impacts from those other actions
 The overall impact that can be expected if the individual impacts are
allowed to accumulate

20. Conclusion
 The above simple techniques of EIA such as impact
identification ,prediction ,evaluation are used for
measuring environment variables and construction of
a number of indices to describe the changes in
environmental inventory.