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In EIA, the term “impacts” is used

instead of “effects of activities.”

Definition of EIA

Environmental Impact Assessment is…

A formal process for identifying:

• likely effects of activities or projects

on the ENVIRONMENT, and on

human health and welfare.

•means and measures to mitigate &

monitor these impacts

Environment is broadly interpreted: physical, biological, and social.

“An assessment of the impact of a planned activity on the

environment”. UNECE (1991)

What to predict?

The object of prediction is to identify the magnitude and other dimensions of identified change in the environment with a project or action, in comparison with the situation without that project or action.

• How any project component may give rise to an impact• Probability of impacts occurring• Magnitude of each impact• Spatial and temporal of each impact

What type of change will happen?

Prediction

After projectBefore project Impact

Generated Cumulative IndirectDirectImpact at different

time

Impact at different

scale

Important Considerations for Impact Prediction

1. Baseline condition (surrounding environment)

2. Uncertainty (anything can be happened)

3. Spatial limits ( place limitation)

4. Temporal boundaries (change of time)

5. Incremental condition

1. EXTRAPOLATIVE METHODS

2. NORMATIVE METHODS

1. MATHEMATICAL MODEL

2. STATISTICAL MODELS

3. GEOGRAPHY INFORMATION SYSTEM

4. FIELD AND LABORATORY EXPERIMENTAL METHODS

5. PHYSICAL MODELS

6. EXPERT JUDGMENTS

Made on the basis of past and present data---

include trend and scenario analysis (the common sense

forecast of the future), analogies (transferring experience from

elsewhere), and intuitive forecasting from group

consensus (Delphi Method).

How the fulfillment of a desired target is achieved.

For example, if in one construction project, a target set is to employ

50% of the local populace. Meeting this target may require

changing the project and associated employment policy.

• based on cause-effect relationships

• usually expressed in the form of mathematical functions. (They may be

simple input-output models or of complex dynamic types.)

• Such models are primarily used for predicting the impact only partially

(e.g., model for phosphorus retention in a lake, or model to predict the

economic multiplier in a particular area).

1. DETERMINISTIC MODELS

2. STOCHASTIC MODEL

Statistical analysis are sometimes used to indicate the relationship

between the data and test hypothesis,

For example, in predicting flood frequencies.

Satellite images, physical maps and aerial photographs provide

information on existing resources.

Prediction of impacts of the development project can be made by

analyzing the effect of project activities on the resources present in

the location by using GIS techniques.

Field inventory carried out prior to project implementation provide the

baseline information of resources.

For example, a fish resource survey in the River of Nepal

indicated that a long-distance migratory fish species are existing in

the river. It could then be determined that the construction of a dam

in the upstream part of the river might create an obstruction for their

upstream migration of the fish for breeding.

These models are closely linked to field and laboratory experiments

making critical engineering and other decisions on site. Basically, a

model of an area likely to be impacted is constructed but on a smaller

scale.

For example, it could show the physical parameters of a Run-

of-river hydropower project. Both natural features such as topography

and socio-cultural features such as villages, schools and bridges are

included. In the case of rivers, the effect of impoundment on flow can

be calculated.

The experience of one place could very well be utilized for similar

places elsewhere where the environmental impacts are unknown

a) Produce acceptable results,

b) Be replicable,

c) Be consistent, and

d) Be adaptable.

Evaluation

The purpose of impact evaluation is to assign relative significance to

predicted impacts associated with the project, and to determine the

order in which impacts are to be avoided, mitigated or compensated.

• Impact assessment involves valuating the significance of the

impacts identified

• Significance can be determined through professional judgment,

reference to regulations etc.

• Potential for bias in determining what is significant

• The conclusions of the impact assessment can ultimately be used

by decision-makers when determining the fate of the project

application

• scientific and professional judgments;

• measure of disturbance to ecological systems;

• impacts on social values and quality of life;

• existence of environmental standards, that is, international, national,

provincial or local agreements;

The key elements for assessing the significance of impacts

include: level of public concern;

1. Level of public concern;

2. Scientific and professional judgment;

3. Measure of disturbance to ecological systems;

4. Impacts on social values and quality of life;

How Is Impact Significance Determined?

Analytical Methods For Impact Evaluation:

Analytical methods seek to introduce a rational approach to

evaluation.

1. COST—BENEFIT ANALYSIS AND MONETARY VALUATION TECHNIQUES

2. SCORING AND WEIGHTING AND MULTI-CRITERIA METHODS

Cost-benefit analysis and monetary valuation techniques:

Cost-benefit analysis and monetary valuation techniques Cost-

benefit analysis itself lies in a range of project and plan appraisal

methods that seek to apply monetary values to costs and benefits

(Litchfield et al. 1975).

Example:Cost Criteria WIND-FARM POWER GENERATOR COAL-FIRED POWER

GENERATORCentralized Generator Distributed Generator

Economic Cost

Initial Cost

site exploration ** *** ***

securing land access ** *** ***

wind turbines and components ** ***

installation cost ** **

foundation cost ** **

Total Initial Cost **** ***** ***

maintenance cost ** ** ***

replacement cost *** *** **

energy production cost ** ** *

transmission cost *** *** **

Total Operational-Maintenance Cost *** *** **

Average plant life 25 years 20 years 50 years

health damage of the society * * **

Environmental Cost

environmental damage * ** ***

emission trading scheme - - ***

Benefit CriteriaWIND-FARM POWER GENERATOR COAL-FIRED POWER

GENERATORCentralized

Generator Distributed Generator

Economic Benefit

reliability + + +++

security of supply +++ +++ ++

Social Benefit

employment opportunities + + +++

Environmental Cost

reduction of air pollution +++ +++ -

Benefit Analysis

Scoring And Weighting and Multi-criteria Methods:

Scoring may use quantitative or qualitative scales, according to

the availability of information on the impact under consideration.

How different levels of impact (in this example noise, whose

measurement is in units of Less 10dBA) can be scored in different

systems. These systems seek to standardize the impact scores for

purposes of comparison (Lee 1987).

The implementation of measures designed to reduce the

undesirable effects of a proposed action on the environment.

Mitigation aims to maximize positive impacts and (particularly)

minimize significant negative impacts.

Mitigation

Impacts remaining after mitigation are known as residual impacts

aim is the identification of likely adverse effects associated with

development, and their mitigation.

Mitigation In EIA Practice:

‘adverse effect’ can be defined as an effect

perceived by the developer or by

stakeholders to cause destruction to an

environmental parameter affected by the

development, either directly or indirectly

1. The source of the effect (for instance, noise emitting

equipment, a toxicant, a tall structure);

2. The receptor (that is, the environmental entity likely to be

adversely affected); and

3. The pathway (the route by which a receptor could be exposed

to the effect)

4. Adverse effect can only occur when all three components are

simultaneously present in the

5. Surrounding environment, as is demonstrated.

Types of Mitigation In EIA :

The Mitigation Hierarchy:

Mitigation hierarchy

Avoid Reduce Remedy Compensate Enhance

Mitigation is the topic of an upcoming module!

Dimension/phase of Mitigation:

1. The phase of the project or timing when mitigations applied —

its ‘implementation phase’; and

2. ‘How to do it’ or the means by which the action envisaged is

to be enacted — the ‘methodology’.

Fig: Linkage between prediction, Evaluation and Mitigation

• Impact prediction and the evaluation of the significance of impacts often

constitute a "black box” in EIA studies.

• Various Impact prediction, evaluation and mitigation are available to the

analyst, and these can help to underpin analysis.

• Mitigation measures come into play particularly at this stage. However,

the increasing sophistication of some methods does run the risk of cutting

out key actors, and especially the public, from the EIA process.

Summary

Thank You ALL…