Chapter 6: Executing the EIA Process - Kathmandu …ku.edu.np/aec/envs402/eia chapter 6.4 methods of...

ENVS402 – Environmental Impact Assessment

Chapter 6: Executing the EIA Process

6.4 Methods of Predictingd E l i Iand Evaluating Impacts

9/16/2011ENVS402 EIA by Dr. Subodh Sharma

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Chapter 6.4: Impact Prediction Methodsp p

Different types of methods are used for impact prediction

1. Mostly, Extrapolative, and2. In some cases, Normative

Extrapolative are those in which the predictions are made on the basis of past and present data, and include trend analysis, scenario analysis, analogies, and intuitive

Normative method examine how the fulfillment of a desired target is achieved

In general, the methods are divided into the following six types (next slides).

9/16/2011ENVS402 EIA by Dr. Subodh Sharma2


1. Mathematical Models2. Statistical Models3. Geographic Models4. Task Specific Computer Models5. Laboratory Experimental Methods6 Biological Methods6. Biological Methods7. Socio‐Economic Method8. Expert Judgmentp g



1. Mathematical Models1. Mathematical Models

• Are used to show cause‐effect relationshipsp

• They may be simple input‐output models or complex

dynamic typesdynamic types

• Primarily used for predicting the impact only partially

d l hi h h i d id h li i• Models which are comprehensive and provide holistic

approach are often rare



1. Types of Mathematical Models1. Types of Mathematical Models

E i i l i t ll d i ti• Empirical or internally descriptive• Generalized or site specific

St ti d i• Stationary or dynamic• Homogenous or non homogenous

D t i i ti• Deterministic or stochastic/probablistic



2. Statistical Models2. Statistical Models

• If methods are used to test hypothesis, statistical yp ,

methods are useful.

• Cause and Effect relationships can be established by• Cause and Effect relationships can be established by

correlation and regression analysis.

l d f i ll di d b h• Flood frequencies are usually predicted by such

methods



3. Geographical Models3. Geographical Models

• Are used to predict impacts over the space and time

• Satellite images, physical maps or aerial photos and GIS

are used



4. Task Specific Computer Models4. Task Specific Computer Models

• Computer models incorporate key processes and

interactions and are used to predict possible changes in

the resource condition that will be affected by the project the resource condition that will be affected by the project

activities over a period of time (Khadka 2001).

• If adequate data are available they are effective and• If adequate data are available, they are effective and

reliable to forecast impacts.



5. Laboratory Experiments5. Laboratory Experiments

1. The field study provides information on the availability, nature and1. The field study provides information on the availability, nature and

conditions of the environmental resources, possible impacts on such

resources can also be predicted, but the level of impacts are difficult to

predict.

2. In such cases, laboratory experiments can be carried out.

3 Laboratory experiments provide information on possible biological3. Laboratory experiments provide information on possible biological

magnification, and concentration of agro‐chemicals on species of prime

importance.



6. Biological Methods(Source: Hongkong Environmental Protection Dept., 1997)

Criteria Remarks

Habitat quality The impact will be more significant if ecologically important habitats are affected (see next slide)

Species The impact will be more significant if ecologically important species are affected (see next slides)

Size/abundance The impact will be greater if larger area of a habitat orSize/abundance The impact will be greater if larger area of a habitat or greater numbers of organisms are affected

Duration Long - term impacts are usually more significants than short -term ones

R ibilit P t d i ibl i t llReversibility Permanent and irreversible impacts are usually more significant than temporary and reversible ones

Magnitude Usually the greater the magnitude of the environmental changes, the more significant is the impact


Chapter 6.4: Impact Prediction Methods

1 Birth7. Socio‐Economic Methods

1. Birth

2. Death

3 Mi ti

Population growor decline

3. Migration

Population change = (births + immigration) – (deaths + emigration)

Population entering

Population change = (births + immigration) – (deaths + emigration)

Population leaving

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8. Expert Judgement

• Specialists are involved in predicting impacts based on

their experiencestheir experiences

• Sound judgement from expert will later be evaluated

by EIA review team

• Expert judgement or Professional Judgement is

considered a ‘best’ estimate



Choice of Prediction Techniques

• It is dependent on the nature, size and location of the projectTh d i EIA i l ibl• The person or team conducting EIA is also responsible for selecting the impact prediction techniques

• Usage of such tools will also vary depending upon the resources (eg., in forest sector, most of the techniques will focus on biological resources)

• Consistency adaptability and replicability influenceConsistency, adaptability and replicability influence selection of tools

• Predictive methods must be simple and easily d t d bl


understandable


Uncertainty in Impact Prediction

• There always exists some sort of uncertainty in prediction; what differs is the confidence limit

• Uncertainty about social, physical and economic environment.• Uncertainty about guiding values such as policies, priorities and

legislation.• Uncertainty about related decisions such as planning, negotiation,

coordination etc.,

‐ all affect the accuracy of prediction in the EIA process


Chapter 6.5: Impact Evaluation Methodsp p

• Evaluation of impacts should be based on comparing the values against set standardsthe values against set standards

• Once an impact is predicted, a decision needs to be made on the significance of the impacts

How Significant is ‘Significant’?There are a number of ways in answering this question:

1. Scoping results may be used as a guide;2. Relevant national laws, regulations or policies which may give

protection to the species;3 Expert judgement (scientists); and3. Expert judgement (scientists); and4. Reconvening the scoping sessions

If a consensus is required amongst stakeholders, then some techniques may be used (see next slides)


may be used (see next slides)


• Evaluation of impacts should be based on comparing the values against set standardsthe values against set standards

• Once an impact is predicted, a decision needs to be made on the significance of the impacts

How Significant is ‘Significant’?There are a number of ways in answering this question:

1. Scoping results may be used as a guide;2. Relevant national laws, regulations or policies which may give

protection to the species;3 Expert judgement (scientists); and3. Expert judgement (scientists); and4. Reconvening the scoping sessions

If a consensus is required amongst stakeholders, then some techniques may be used (see next slides)


may be used (see next slides)

CRITERIA AND STANDARDS FOR ASSESSING CRITERIA AND STANDARDS FOR ASSESSING SIGNIFICANT ENVIRONMENTAL IMPACTS......

Definition of Criterion & Standard.......Criterion means a scientific requirement on which a decision or judgement may be based concerning the suitability of the government to support a designated use (WHO, 1978).

Standard means an authoratative or recognised exemplar or correctness perfection or some definite degree of any quality (Oxford correctness, perfection or some definite degree of any quality (Oxford Univ., 1978).

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Meaning of Significant Environmental ea g o S g ca t o e taImpacts...

Environmental Significance is a judgement;

the degree of environmental significance depends upon the nature the degree of environmental significance depends upon the nature (type, magnitude, extent, duration, intensity etc.) of environmental impacts and their importance;

the importance is rated in terms of both bio-physical and socio-economic values;

it i l th t f h t th i t i d t it involves the amount of change to the environment perceived to be acceptable to the community -including cumulative change.

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D i i tDecision tree..Potential impact (see next slide)p ( )

What is the impact? (The fact)How important or significant is it? (The meaning)How important or significant is it? (The meaning)

Is it - in total:

Acceptable Manageable Unacceptable

With t’ With regulatoryWith proponent’scommitments

With regulatorycontrols Redesign to

remove or avoidAbandon in part or whole

Proceed to next step Stop19

Examples of threshold tests for environmental acceptability...

Level of acceptability Potential impact threshold

Unacceptable Exceeds legal threshold, eg. quality standard

Unacceptable Increases level of risk to public health and safety abovequalitative or quantitative criteriaqualitative or quantitative criteria

Unacceptable Extinction of biological species, loss of genetic diversity,rare or endangered species, critical habitat

Normally unacceptable Conflict with existing environmental policies, land-useplans

Normally unacceptable Loss of populations of commercial biological species

Normally unacceptable Large-scale loss of productive capacity of renewableresources

May be acceptable only with minimization, Avoidance of spread of biological disease, pests, feralmitigation, management animals, weeds

May be acceptable only with minimization,mitigation, management

Taking of rare or endangered species

May be acceptable only with minimization,mitigation management

Some loss of threatened habitatmitigation, management

Normally acceptable Some loss of populations and habitats of non-threatenedspecies

Normally acceptable Modification of landscape without downgradingspecial aesthetic values

Normally acceptable Emissions demonstrably less than the carrying capacity ofthe receiving environment20

Impact Evaluation Techniques1. Nominal Group Process Technique (NGP) – NGP is an interactive group

technique developed in 1968 .2 D l hi T h i (DM) DM i h bj i h d h2. Delphi Technique (DM)‐ DM is another subjective method that

involves the participation of stakeholders. This is a good method to bring consensus among stakeholders.Determining the relative importance of impacts is an importantDetermining the relative importance of impacts is an important aspects of evaluatione.g., Is the decline in the fishery of equal importance to the noise level increase, or is it same important?level increase, or is it same important?

3. Environmental Evaluation System (EES) – This is one of the oldest technique for evaluation of impacts. Basis of importance value ranges q p p gfrom 0‐1. The environmental evaluation system was designed by the Battelle Columbus Laboratories in the United States to assess impacts of water-resource developments, water-quality management plans, highways, nuclear power plants and other projects (Dee et al 1972 1973)


plants, and other projects (Dee et al., 1972, 1973).


• EES Methods are considered to be quite reliable they• EES Methods are considered to be quite reliable, they are criticized for being entirely based on the opinions of judges.

• The use of scalar is questionable (Parameters Important Units).

• Environmental categories are counted twice, and this g ,method cannot account for secondary and higher order interactions.


Chapter 6: Executing the EIA Process - Kathmandu …ku.edu.np/aec/envs402/eia chapter 6.4 methods of...

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