CHAPTER- 3

EIA TECHNIQUES

EIA techniques refers to ways and methodologies of identifying

the major social, environment, and cultural impacts of project.
There are different methods that can be applied to point out the
imperative issues that need to be addressed in an EIA report.
These techniques vary depending on the project and the resources
at our disposal.
1
Qualities of appropriate technique to evaluate a project:
It should be systematic in approach

It should be able to organize a large mass of heterogeneous data

It should be capable of summarizing such data

It should have good predictive capability

It should be able to finally display an information in a meaningful fashion.

2
The available techniques include the following:
A. Baseline studies

B. Checklists

C. Matrices

D. Network Diagrams

E. Overlays

F. Battelle Environmental Evaluation System

G. Mathematical Modelling etc…

3
A) Baseline studies
The term "baseline" refers to the collection of background information on the biophysical,
social and economic settings of proposed project area

Baseline data is collected for two main purposes:

To provide a description of the current status and trends of environmental factors (e.g.,
air pollutant concentrations) of the host area against which predicted changes can be
compared and evaluated in terms of significance, and

To provide a means of detecting actual change by monitoring once a project has been
initiated

4
Baseline studies require information on the following:

 Current conditions

 Expected trends

 Effects of proposals already being implemented

 Effects of other proposals yet to be implemented

5
B. Checklist method

 Checklist means a listing of potential Environmental Impacts.

 Checklists are comprehensive lists of environmental effects and impact indicators

designed to stimulate the analyst to think broadly about possible consequences of
contemplated actions
This method is done to assess :

 The nature of the impacts

 Short term or long term

 No effect or significant impact

 Reversible or irreversible impact etc….

6
Type of checklists:

1. Simple Checklist: a list of environmental parameters with no guidelines on how they

are to be measured and interpreted.

7
2. Descriptive Checklist: includes an identification of environmental parameters and
guidelines on how to measure data on particular parameters.

3. Scaling Checklist: similar to a descriptive checklist, but with additional information on

subjective scaling of the parameters.

4. Scaling Weighting Checklist: similar to a scaling checklist, with additional information

for the evaluation of each parameter with respect to all the other parameters

8
Westman (1985) listed some of the problems with checklists when used as an impact
assessment method:

1. They are too general or incomplete

2. They do not illustrate interactions between effects

3. The number of categories to be reviewed can be immense, thus distracting from the most
significant impacts; and

4. The identification of effects is qualitative and subjective.

9
 Checklist

Advantages: Disadvantages:

• Simple to understand and use • Do not distinguish b/n direct and indirect
impacts
• Good for site selection and priority setting
• Do not link action and impact

• Qualitative

10
C. Matrix method
• Matrix method identify interactions between various project actions and environmental
parameters and components. i.e. action vs impact

• 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 pioneered by Leopold et al(1971).

He listed about 100 project actions and about 88 environmental characteristic and condition.

11
12
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

13
D. Network approach
It uses the matrix approach by extending it take into account primary as well the
secondary impacts.

Some features of network method include:

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

14
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

15
E. Overlay Technique
The overlay approach to impact assessment was first suggested by Dr. Ian McHarg at the
University of Pennsylvania.

Rely on a set of maps of a project area’s environmental characteristics covering physical ,

social, ecological, aesthetic aspects.

Can also use separate mapping of critical environmental features at the same scale as
project's site plan.

16
 Older Technique: Environmental features are mapped on transparent plastic in
different colors.

 Newer Technique: Geographic Information Systems (GIS).

Ecological site
Historic site
Health
Settlement
Noise
water

17
Maps are prepared for the following systems of concern

1. Economic systems
Agricultural land

Area utilities and industry

2. Social aspects
Recreational, historical and cultural

3. Natural systems
Natural landscape, diversity
 On each map was produced grids of the same size with impact rate of 1 (low) to 5 (high)
assigned to each grid
18
19
Advantages

Because of predictions are made for each unit area, the overlay method is strong in
predicting spatial patterns,

The possibility of displaying magnitudes by colour, coding or shading

The ease with which the system can be programmed on a computer to provide
composite charts that can be readily understood.

20
Disadvantages
The approach is only moderately comprehensive because there is no mechanism that
requires consideration of all potential impact.

The approach is selective because there is a limit to the number of transparencies that can
be viewed together.

Overlays are not effective in estimating or displaying uncertainty and interactions.

21
F. Battelle Environmental Evaluation System

The environmental evaluation system was designed by the Battelle Columbus Laboratories
in the United States.

Used to assess impacts of water-resource developments, water-quality management plans,

highways, nuclear power plants, and other projects
This method takes the item-by-item evaluation approach and then determines a numerical
value function of each parameter
The evaluation technique is used to evaluate the expected future condition of the
environmental quality, both ‘with’ and ‘without’ the project

22
A difference in environmental impact units (EIU’s) between those two conditions constitute
either an adverse impact, which corresponds to a loss of EIU’s, or a beneficial impact, which
corresponds to a gain in EIU.

The principle splits the environmental impact in to four impact categories.

Ecology

Physical/chemical

Aesthetics

Human interest

23
Mathematically:

m m
E1   V 
i 1
i  Wi   Vi   Wi
i 1
1 2

• Where:

• E1 = value in environmental impact

• (V)i1 = value in environmental quality of parameter I ‘with’ project

• (V)i2 = value in environmental quality of parameter I ‘without’ project

• Wi = relative weight (importance) of parameter i

• m = total no. of parameters

24
Exercise : Given that a dam/reservoir with a reservoir surface elevation at 200m AMSL is
supposed to be constructed for a multipurpose WRD project. An EIA team is assigned to
evaluate the environmental impact of the project.

Methodology: Checklists of major impacts were prepared to help for an item by item
evaluation using the Battelle Environmental Evaluation system .

More information follows in the next slides

25
ITEM ENVIRONMENTAL QUALITY WEIGHT
With project Without project

Flow variation Moderate deterioration Very slight change 35

Climatic change Slight deterioration No change 15

Land loss Moderate deterioration No change 35

Agricultural Improvement Significant change 95

Production
Domestic water Improvement Moderate change 60
supply
Reservoir leakage Slight deterioration No change 10

Fishery Improvement No change 40

26
Figure: Value function with project

27
Figure: Value function without project

28
Questions

1. Determine the value function for each parameter by referring to the value
function provided.

2. Determine the Environmental Impact Unit (EIU) for each parameter with and
without project using Battelle EES.

3. Determine the net change in EIU.

29
Question 1:
Value function for each parameter
With project Without project
Parameter Scale Environmental Parameter Scale Environmental
Quality Quality
Extensive Deterioration 0.2 Significant change 0.2

Moderate deterioration 0.4 Moderate Change 0.4

Slight deterioration 0.6 Slight Change 0.6

No change 0.8 Very Slight Change 0.8

Improvement 1 No change 1

30
Question 2: Environmental Impact Unit (EIU) for each parameter with and without
project
ITEM EIU CALCULATION
With project Without project
Flow variation 0.4*35=14 0.8*35=28
Climatic change 0.6*15=9 1*15=15
Land loss 0.4*35=14 1*35=35
Agricultural Production 1*95=95 0.2*95=19
Domestic water supply 1*60=60 0.4*60=24
Reservoir leakage 0.6*10=6 1*10=10
Fishery 1*40=40 1*40=40
total 238 `171
31
Question 3
The net EIU is calculated as:

m m
E1   V   W   V 
i 1
i i
i 1
i  Wi
1 2

E1= 238 - 171= 67 (positive effect)

32
G. Mathematical modelling
• Mathematical modelling is one of the most useful tools for prediction work.

• It is based on a set of theoretical and practical knowledge about an action and its potential
impact.

• Requires good computational and graphic capacity from computers.

• In a mathematical model the behavior of an environmental system is represented by mathematical

expressions of the relationships between variables.

• In general the output variable (x) is a function of one or more input variables (A,B,C,...):

X = f(A,B,C,...) Examples:

- Salt/water balances,

- Pollution transport,

-Changing flood patterns/Soil loss 33

THE END!

THANK YOU!!

34