UNIT – II

EIA METHODOLOGIES
 There are some simply and widely used EIA Methods are
described along with the criteria to be followed for choosing
most appropriate method in a given situation.

Each Method and technique for the evaluation of impact

should have the following qualities and characteristics

1) It should be systematic in approach

2) It should be able to organize a large mass of heterogeneous

data

3) It should be able to quantify the impacts

4) It should be capable of summarizing the data

5) It should have good predictive capability

6) It should finally able to display the raw data and the derived
functions

7) It should extract the salient features

8) It should be able to aggregate the data into sets with least loss
of information because of the aggregations
 Criteria for the selection of EIA methodology

1) General

2) Impact identification

3) Impact measurement

4) Impact interpretation and Evaluation

5) Impact communication
1) General:

a) Simplicity: The methodology should be simple so that the

available manpower with limited background knowledge can
grasp and adopt it without much difficulty

b) Manpower time and budget constraints: This methodology

should be applied by a small group with a limited budget and
under time constraints
c) Flexibility: The methodology should be flexible enough to
allow for necessary modifications and changes through the
course of the study
2) Impact Identification

a) Comprehensiveness: The methodology should be

sufficiently comprehensive to contain all possible options and
alternatives and should give enough information on them to
facilitate proper decision making

b) Specificity: The methodology should identify specific

parameters on which there would be significant impacts
c) Isolation of project impacts: The methodology should
suggest procedures for identifying project impacts as
distinguished from future environmental changes produced by
other causes

d) Timing and duration: The methodology should be able to

identify accurately the location and extent of the impacts on a
temporal scale
3) Impact Measurement

a) Commensurate units: The methodology should have a

commensurate set of units so that comparison can be made
between alternatives and criteria

b) Explicit Indicators: The methodology should suggest

specific and measurable indicators to be used to qualify
impacts on the relevant environmental parameters
c) Magnitude: The methodology should provide for the
measurement of impact magnitude, defined as the degree of
extensiveness of scale of impact

d) Objective criteria: It should be based on objective criteria

and the criteria should be stated explicitly
4) Impact Interpretation and Evaluation

a) Significance: The methodology should be able to assess the

significance of measured impacts on a local, regional and
national scale
b) Explicit criteria: The criteria and assumptions employed to
determine impact significance should be explicitly stated
c) Portrayal of “with” and “without” situation: The
methodology should be able to aggregate the vast amounts of
information and raw input data
d) Uncertainity: Uncertainity of possible impacts is a very real
problem in environmental impact assessment. The
methodology should be able to take this aspect into account

e) Risk: The methodology should identify impacts that have low

probability of occurrence but a high potential for damage and
loss

f) Depth of analysis: The conclusions derived from the

methodology should be able to provide sufficient depth of
analysis and instill confidence in the users, including the
general public
g) Alternative comparison: It should provide a sufficiently
detailed and complete comparison of the various alternatives
readily available for the project under study

h) Public Involvement: The methodology should suggest a

mechanism for public involvement in the interpretation of the
impacts and their significance
5) Impact communication

a) Affected parties: The methodology should provide a

mechanism for linking impacts to specific effected
geographical or social groups

b) Setting description: It should provide a description of the

project setting to aid the users in developing an adequately
comprehensive overall perspective
c) Summary format: It should provide the results of the impact
analysis summarized in a format that will give the users, who
range from the lay public to the decision makers, sufficient
details to understand it and have confidence in its assessment

d) Key issues: It should provide a format for highlighting the key

issues and impacts identified in the analysis

e) Compliance: One of the most important factors in choosing a

methodology is whether it is able to comply with the terms of
reference established by the controlling agency
 EIA Methods

The following are the important methodologies of utility for

assessing the impacts of developmental activities on the
environment

1. Adhoc Methods

2. Networks Methods

3. Overlays Methods

4. Checklists Methods

5. Matrices Methods
1)Adhoc Method:

It indicates the broad areas of possible impacts by listing

composite environmental parameters (for example flora and
fauna) likely to be affected by any development

In this method a team of exports sit together to conduct the total

impact assessment and suggest the broad areas of possible
impacts
The conclusion are based on Experience , training and
intuition of experts involved in the discussion

The primary advantage of these method is the possibility to

modify it according to specific circumstances .

The information in this method can be easily understood by a

layman person
In this method, each environmental area, such as air and water
is taken separately and the nature of impacts such as short-
term or long term, reversible or irreversible are considered

These methods are rough assessment of total impact giving the

broad areas of possible impacts and the nature of these
possible impacts
This method serves as a preliminary assessment which helps in
identifying more important areas like:

1) Wild life
2) Endangered species
3) Natural vegetation
4) Exotic vegetation
5) Grazing
6) Social characteristics
7) Natural drainage
8) Groundwater
9) Noise
10) Air quality
Draw backs:

Provides Little or no guidance for an impact assessment

May not include all the relevant impacts

It suggests broad area of possible impacts but lacks

information about cause effect relationship

Very poor for identification, prediction and analysis of

impact
As the expert judgement in assessing the primary impacts is
done in an Adhoc manner it cannot be replicated making it to
review or analyse the conclusions in EIA

As considerable amount of information about the social,

economic, biological and physical environment are to be
collected and analysed in EIA of any project activity Adhoc
methods fail to do this in any meaningful way
Because of the above drawbacks, it is not recommended as a
method for impact analysis.

It is after all Adhoc method and has utility only when other
methods cannot be used for lack of expertise, resources and
other necessities
2)Network Method

These are capable of identifying direct and Indirect

impacts , higher order effects and interaction between
impacts .
Hence these are able to identify and incorporate
mitigation and management measures into the planning
stages of a project
Network Method is used in predicting the potential
impact by using directional diagram in an easy to
understand manner .
In these method the primary, secondary, and tertiary impact
resulting from the development activities are envisioned and
the web of environment relationships are depicted in the form
of network.

To develop a network a series of questions related to each

project activity( such as what are primary impacts and
secondary impacts and so on)
In developing a network diagram the first step is to identify the
first order changes in environmental components

The secondary changes in other environmental components

that will result from first order changes will be then identified

In turn third order changes resulting from secondary changes

will be then identified

This process will be continued until the network diagram is

completed to the experts satisfaction
fig.
Example
Fig. Network of pulp mill impacts
Fig.. Measure diagram for the aerial applications of herbicide
Networks can become very visually complicated

Networks generally consider only adverse impacts on the

environment and hence decision making in terms of the cost
and benefit of a development project to a region is not feasible
by network analysis

These are capable of presenting scientific and factual

information but provide no avenue for public participation
3) Overlay Method

In this method the environmental impacts are displayed

pictorially on a transparent maps. which represent the spatial
distribution of an environmental characteristic
For example , where a highway has to be constructed

1) A map showing forest region

2) A map showing agriculture region

3) A map showing topography

4) A map showing roads connecting to the near by Towns and

cities
fig.
Fig..shows the resulting composite maps characterize the areas
physical, social, ecological, land use and other relevant
characteristics relative to the location of the proposed
development
These methods are widely used for assessing visually the
changes in the landscape before and after the activity
Secondly it can be used for preparing combined mapping with
an analysis of sensitive areas
As these methods are spatially oriented they can very clearly
show the spatial aspects of cumulative impacts
Overlays are very subjective in that they rely on the judgement
of the analyst to evaluate and assess questions on compatibility
relating to the existing land use patterns

These are self-limiting because there is a practical limit on the

number of transparencies that can be overlaid

These are useful when addressing questions of site and route

selection
These can be useful for industrial EIA of any project for
comparing land capabilities existing and projected land use,
road route alternatives

Overlays cannot be used to quantify impacts to identify

secondary and tertiary interrelationships
Evaluation of geospatial EIA method
4)Checklists method

Checklists methodologies range from listings of environmental

factors in highly structured approaches involving importance
weightings for factors and application of scaling techniques

These are strong in impact identification and are capable of

bringing them to the attention and awareness of their audiences
Checklists are of four broad categories and represent one of the
basic methodologies used in EIA. They are:

1) Simple Checklists

2) Descriptive Checklists

3) Scaling Checklists

4) Scaling weighting Checklists

1) Simple Checklists: are a list of parameters without
guidelines provided on how to interpret and measure an
environmental parameter

2) Descriptive Checklists: includes an identification of

environmental parameters and guidelines on how parameter
data are to be measured
3) Scaling Checklists: are similar to descriptive checklist with
the addition of information basis to subjective scaling or
parameter values

4) Scaling weighting checklists : are capable of quantifying

impacts
 Simple checklists

This method represents a valid approach for providing

systemization to an EIS

Table presents a list of environmental factors to be considered

in construction and operational phases.

The checklist also includes information on mitigation

2)Descriptive checklists

These are widely used in environmental impact studies

A portion of descriptive checklists containing several factors

for housing and other land development projects are shown in
table
Important characteristics of simple and descriptive checklists

1) These consider environmental factors or impacts which can

be helpful in planning and conducting an EIS

2) They have professional credibility and usability

3) These provide a structures approach for identifying key

impacts and can be modified

4) Can be used to simulate interdisciplinary team discussions

during the planning, conduction and summarization of EIS
5) Any special impact codes used within the checklists should
also be defined
6) Impacts from these can be grouped together to demonstrate
secondary and tertiary impacts
7) Important weights could be assigned to key environmental
factors or impacts and these should be delineated
8) Key impacts which should be mitigated can be identified
through systematic usage of a simple or descriptive checklist
Checklists are mainly useful for:

a) Summarising information to make it accessible to experts in

different fields or decision makers who have little technical
knowledge

b) Preliminary analysis will be available in scaling checklists

c) Information on ecosystem functions can be clearly

understood from weighting methods
Some of the drawbacks of checklists are:

a) They are too general or incomplete

b) They do not illustrate interactions between effects

c) The number of categories to be reviewed can be immense,

which will create confusion about significant impacts

d) Involves the identification of effects which are qualitative and

subjective
 EIA Review

Review is a mechanism employed in Environmental Impact

Assessment (EIA) to judge the adequacy of the process and
quality of the EIA report.

The review is conducted with reference to legal conformity

and good practice
Key objectives of EIA review are to:

Assess quality of information contained in the EIA report

Determine how stakeholder concerns have been addressed

Determine if the information is adequate for decision-making

and

Identify information gaps and deficiencies.

The purpose of review is to determine whether the information is
sufficient for decision-making

The type of information needed for decision-making includes:

a) Description of the project proposal and activities

b) Description of the baseline environmental conditions

c) Identification, quantification and evaluation of impacts

d) Identification and evaluation of the full range of reasonable

alternatives and

e) Description of mitigation measures.

Principles for EIA Review:
The following aspects are listed by UNEP (2002) for
consideration in a comprehensive EIA review:
1) Performance of scoping
2) Accuracy of impact prediction
3) Comparison of alternatives
4) Effectiveness of proposed mitigation measures
5) Requirements for monitoring and
6) Process and method for stakeholder engagement
Comprehensive EIA(CEIA) :

CEIA study is a pre-requisite for getting Environmental

clearance from Ministry of Environment & Forests,
Government of India and No Objection Certificate(NOC) from
the state pollution control Board
 Construction stage impacts:

These adverse environmental impacts like waste, noise, dust,

solid wastes, toxic generation, air pollution, water
pollution, bad odour, climate change, land use, operation
with vegetation and hazardous emissions.
emissions

Air emissions are generated from vehicular exhaust, and dust

during construction