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
(3)It should be economical in terms of costs, and its
requirement of data ,investigating time ,
personnel, equipment and facilities.
This stage of EIA identifies and
predicts the likely Environmental and
social impact of the proposed project and
evaluates the significance
*Public involvement typically
occurs at these points.
It may also occur at any
other stage of the EIA Process
Information from this process
contributes to effective EIA in the future
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.
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
When more scientific methods are available, it is not
Specialists on a
particular area will
It require expert.
impact are merely
examined on guess
impacts are quite
Checklist means a listing of potential
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
Good for site
Do not distinguish
between direct and
Do not link action
Sometime it is a
Matrix and its variants provide us a
framework of interaction of different actions
/activities of a project with potential EI caused
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
It was pioneer by Leopold et al(1971).
It lists about 100 project actions and about 88
environmental characteristic and condition.
Link action to
Good method for
It uses the matrix approach by extending it
take into account primary as well the
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
Temperature Flow Water Quality
Access Dredging Clearing
Link action to
simplified form in
overly complex if
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
Older Technique: environmental features are
mapped on transparent plastic in different colors.
Newer Technique: Geographic Information Systems
Good for site
Do not address
A. Biological and Physio -chemical impacts.
B. Social impacts.
C. Health impacts.
D. Economic impacts.
It relate to effects on biological resources such
as vegetation ,wildlife , crops and aquatic life.
Interaction with Physical elements like air
,water , soil, rocks and solar radiation.
Chemical impacts like chemical change in air ,
water , soil quality etc.
Demographic – Displacement and
relocation effects and changes in
Cultural – Traditional patterns , family
structure ,religious, archaeological
features , social networks.
Gender – implication of projects on
roles of women in society ,
employment opportunity and equity
Institutional – Housing , schools,
Criminal justice , Health, welfare
Examples of health impacts by sector
Nutrition Injury Psychosocial
loss of well-
Mining Tuberculosis Dust induced
Crushing Labour migration
Industry Poisoning by
Forestry Loss of food
Transportation HIV/Aids Heart disease Traffic injury Noise and
Energy Indoor air
Duration of construction and operation
Workforce requirements for each period
Skill requirements (local availability)
Raw material and other input purchases
The characteristics of the local economy
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.
Best estimate professional judgement .
Quantitative mathematical models .
Experiments and physical models .
Case studies as analogues or
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
Importance of affected resource
Magnitude and extent of disturbance
Duration and frequency
Risk/likelihood of occurrence
Contribution to cumulative impacts
Be considered effective if
Information generated in the EIA contributed to
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
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
The overall impact that can be expected if the
individual impacts are allowed to accumulate
Select Final Environmental
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.