CHAPTER – 2

EIA METHODOLOGIES
Desirable of EIA Methodologies:
EIA Methodology are based on principle of equality, openness, cost effectiveness and efficiency
approaches. Broadly these are 4 types.
(a) Comprehensive: Recognize intricate systems and bound complex interrelationship.
(b) Selective: Pinpoint critical (significant) impacts and eliminate as early as possible unimportant
impacts.
(c) Comparative: Determine environmental changes due to the project activities compared with under
existing conditions (Before starting project).
(d) Objective: Provide unbiased measurements free from political and external influences.

Criteria for selection of EIA Methodology:

(a) Simplicity: The methodology should be simple and based on available manpower & background
knowledge. It can be adapted without much difficulty.
(b) Budget and Time: The methodology should be applied by small group with under approve budget
and limited time span.
(c) Flexibility: The method should be flexible and allow the modifications and changes during course of
study.

Choosing a Method:
The methodology of EIA ranges from simple to complex and requires different kinds of data, several
data formats, expertise and technological skill for their interpretation. Their analyses produce differing
levels of precision and certainty. All of these factors should be considered for selecting a suitable
methodology.

II. 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.
III. Impact measurement
a) Commensurate units:
It should have a commensurate set of units so that comparison can be made between alternatives and
criteria.

b) Explicit indicators:
It should suggest specific and measurable indicators to be used to qualify impacts on the relevant
environmental parameters.

c) Magnitude:
It should provide for the measurement of impact magnitude, defined as the degree of extensiveness of
scale of the impact, as distinct from impact importance, defined as the weighing of the degree of
significance of the impact.

d) Objective criteria:
It should be based on objective criteria and the criteria should be stated explicitly.

IV. 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 “with out” situation:
The methodology should be able to aggregate the vast amounts of information and raw input data.
d) Uncertainty:
Uncertainty 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.
f) Public involvement:
The methodology should suggest a mechanism for public involvement in the interpretation of impacts
and their significance.
V. 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 be 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 user, 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.

Objectives of Methodologies
Understand the nature and location of the project and possible alternatives
Identify factors of analysis and assessment objectives
Preliminary identification of impacts and scoping
Baseline studies and evolution in the absence of projects
Prediction and assessment of impacts and alternatives comparison
Mitigation of impacts management.

Requirements of EIA Methodologies

The EIA Practitioner faces vast varieties of raw and unorganized information that must be
collected and analyzed in preparation of an EIA report.
The best methods should be able to
Organize a large mass of heterogeneous data
Allow summarization of data
Aggregate the data into smaller sets with least loss of information
Display the raw data and the derived information in a direct and relevant fashion
Target audience should also be considered (if not educated use color codes, size etc.)

EIA Methodology Evaluation

Major Methodologies for EIA
The methodologies can be broadly divided into five types on the basis of impact identification strength.
1. Ad hoc methods
2. Matrices methods
3. Network methods
4. Overlays methods
Ad hoc Method
Ad hoc methods indicate broad areas of possible impacts by listing composite environmental parameters
(Ex: flora and fauna) likely to be affected by the proposed activity. These methods involve assembling a
team of specialists who identify impacts in their area of expertise. Here, each parameter is considered
separately and the natures of impacts (long term or short term, reversible or irreversible) are considered.
These methods give a rough assessment of total impact while giving the broad areas and the general
nature of possible impacts. In this method, the assessor relies on an intuitive approach and makes a
broad-based qualitative assessment. This method serves as a preliminary assessment and helps in
identification of important areas like:
1. Wildlife
2. Endangered species
3. Natural vegetation
4. Exotic vegetation
5. Grazing
6. Social characteristics
7. Natural drainage
8. Groundwater
9. Noise
10. Air quality
11. Visual description and services
12. Open space
13. Recreation
14. Health and safety
15. Economic values and
16. Public facilities

Types of Ad hoc method are:

a) Opinion poll
b) Expert opinion and
c) Delphi methods
This method is very simple and can be performed without any training. It does not involve any relative
weighting or any cause-effect relationship. It provides minimal guidance for impact analysis while
suggesting broad areas for possible impacts. Moreover, it does not even state the actual impacts on
specific parameters that will be affected.
The drawbacks of this method are listed below:
1. It gives no assurance that a comprehensive set of all relevant impacts have been studied.
2. Analysis using this method lacks consistency as it different criteria are selectively
evaluated by different groups.
3. It is blatantly inefficient as it requires a considerable effort to identify and assemble a
panel for each assessment.

Example
EIA Study for High way Construction Project

Matrices Method
This methodology provides a framework of interaction of different activities of a project with potential
environmental impacts caused by them. A simple interaction matrix is formed when project actions are listed on
one axis (usually vertical) and environmental impacts are listed along the other axis. This technique was
pioneered by Leopold et al in 1971. It lists about 100 project actions and about 88 environmental characteristics
and conditions. An example of this matrix is shown below:
Importance of Matrices
Matrices are two dimensional tables.
These facilitate the identification of impacts arising from the interaction between project activities
and specific environmental components.
The entries of the cell of the matrix can be either qualitative or quantitative estimates of impact.
i) Simple Matrix
 ii)

ii) Leopold Matrices

Identify all actions that are part of the proposed project
Under the each of the proposed actions, place a slash at the inter-section with each item
on the side of the matrix if an impact is possible.

In the upper left hand corner of each box with a slash, place a number from 1 to 10 which
indicates the MAGNITUDE of the possible impact.
10 represent the greatest magnitude of impact.
1 is the least magnitude of impact (no zeroes).
Before each number place + (if the impact would be beneficial).
In the lower right hand corner of the box place a number from 1 to 10 which indicates the
IMPORT ANCE of the possible impact (Eg. Regional vs. Local).
10 represents the greatest importance and 1 the least (no zeroes).

Advantages:
1. The matrix method is that it links action to impact
2. This is a very good method for displaying EIA result.
Disadvantages:
o It is difficult to distinguish between direct and indirect impacts using this method.
o There is potential for double-counting of impacts.
o It is qualitative in nature and does not refer to quantity of impact.

Network Method
This method uses the matrix approach and extends it to include both the primary as well as the
secondary impacts.
It is shown in the form of a tree called impact tree. This diagram is also called as reference or
sequence diagram.
Identification of direct, indirect along with short, long term impact is a crucial and basic step of
making an impact tree.
The impact tree is used to identify cause-effect linkages.
The impact tree is a visual description of linkages.
Example

Advantages:
It links action to impact.
It is useful to check second order impacts in a simplified form.
It handles direct and indirect impacts.
Disadvantages:
It becomes overly complex if used beyond simplified version.
It is completely qualitative in nature.

Overlays Method
1. Overlay methods involve preparation of a set of transparent maps, which represent the spatial
distribution of environmental characteristics (e.g., Extent of dense forest area).
2. Information on wide range of variables will be collected for standard geographical units within the
study area which will be recorded on series of maps typically one for each variable.
3. These maps will be overlaid to produce a composite.
4. The resulting composite maps characterize the area's physical, social, ecological, land use and other
relevant characteristics relative to the location of the proposed development.
5. To evaluate the degree of associated impacts many project alternatives can be located on the final map
and validity of the assessment will be related to the type and number of parameters chosen.
6. Normally to have some clarity the number of parameters that can be over layed in a transparency map
is limited to 10.
7. These methods are widely used for assessing visually the changes in the landscape before and after
the activity.
8. Secondly it can be used for preparing combined mapping with an analysis of sensitive areas or
ecological carrying capacity.
9. As these methods are spatially oriented they can very clearly show the spatial aspects of cumulative
impacts.
10. These maps are overlaid to produce a composite characterization of the regional environment.
11. Impacts are identified by noting the impacted environmental characteristics lying within the project
boundaries.
12. The approach seems most useful as a method of screening alternative project sites or routes, before
detailed impact analysis.
13. Overlays can be useful for industrial EIA of any project for comparing land capabilities existing and
projected land uses, road route alternatives and other under parameters, and alternative levels of air
quality conditions along with pollution control.
Advantages:
It is easy to understand and use
It has a good display
It is good for setting site selection
Disadvantages
The overlay method can accommodate both qualitative and quantitative data.
The weakness of the overlay method is that it is only moderate comprehensive, because there is no
mechanism that requires consideration of all potential impacts.
There is no provision for quantification and measurement of the impacts nor is it assured that all
impacts will be covered.
The overlay approach is generally effective for selecting alternatives and identifying certain types of
impacts; however, it cannot be used to quantify impacts to identify secondary and tertiary
interrelationships.
Provision for service roads/alternate road connectivity, two-laning/ four-laning/ sixlaning, riding
quality, bypasses and over-bridges, bridges amenities. Based on these factors, the investment needs can
be calculated.

Example:
Highway Road Authority
The road authority costs include
Expenditure involved in the construction and maintenance of roads.
Acquiring the land from the land owners and providing appropriate compensation, expenses incurred
in setting up fences and land scaping .
Construction of noise barriers to reduce the sound entering the residential locality by absorbing,
transmitting or reflecting the sound.

Highway Cost Components

1. Agency Cost
This includes the expenses incurred by the government or private agency for construction and
maintenance of highway roads.
a) Construction cost includes
o Expenses incurred in surveying, planning and designing.
o Purchasing land from the land owners to lay road.
o Construction of road.
o Installation of electrical poles, traffic control equipment.
o Administrative cost involved in supervising the traffic.
b) Maintenance cost includes
o Periodic repair of the damaged roads.
o Relocation and rehabilitation of the displaced people .
o Expenses incurred in maintaining and operating the traffic related equipment.

2. User Cost
This includes the cost incurred in vehicle operation and cost due to the unavoidable accidents, cost
incurred in vehicle operation, fuel, spare parts, wear out of the tires, lubricants, registration
charges ,insurance expenses, road tax and road permit tax etc.

Benefit components of highway road

A well maintained highway road provides efficient and safe transportation to the road users.
The benefits include saving in travel time.
Improvement in health, education, agriculture, industry trade and various other fields.
Checklists:

Checklists are standard lists of the types of environmental potential impacts, which may be associated
with respective project. The lists are prepared with highly structured approaches and involve importance
with weighing of factors and ensure that no potential impact is overlooked. Checklists are very effective
in impact identification and capable to spread awareness & attention for respective people. Checklists
should enable identification of impacts on Soil, Water, Atmosphere, Flora, Fauna, Resources, Recreation
and Cultural etc. status.

A typical checklist might contain entries such as:

 Earth: Mineral Resources, Construction Material, Soils, Land form, Force fields and Background
Radiation, Unique physical features

 Water: Surface water like rivers, lakes and reservoirs, estuaries, coastal seas and ocean, Groundwater
quality, Snow, Ice

 atmosphere: Quality regarding gases & particles), Climate, Temperature

 Flora: Trees, Shrubs, Grass, Crops, Micro & Macro flora, aquatic plants; endangered species;
barriers; corridors

 Fauna: birds; land animals including reptiles; fish and shellfish; benthic organisms; insects; micro
fauna; endangered species; barriers; corridors

 Land Use: Wilderness and open space, Wetlands, Forestry; Grazing, Agriculture, Residential,
Commercial, Industrial, Mining and Quarrying

 Recreation: Hunting; Fishing; Boating, Swimming, Camping and Hiking, Picnicking Resorts

 Types of Checklists

(i) Simple Checklist

(ii) Descriptive Checklists

(iii) Scaling Checklist

(iv) Scaling Weighting Checklist

(v) Questionnaire Checklist

(i) Simple Checklist

Simple checklist consist simple list of environmental parameters and no information needed on the
magnitude or importance of impacts. Checklist can recognize resource/environmental component, which
affects by particular activities. The example given below (Table 1) for construction sites, the tick mark
confirm that impact is there, where no tick mark or leaving the box means no impact.

Table 1: Example of Simple Checklist