Impact Prediction, Evaluation And Mitigation in EIA

What is EIA?“An assessment of the impact of a planned activity on the environment”. UNECE (1991)

“The term ‘environmental assessment’ describes a technique and a process by which information about the environmental effects of a project is collected, both by the developer and from other sources, and taken into account by the planning authority in forming their judgments on whether the development should go ahead” UK DoE (1989)

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In EIA, the term “impacts” is used instead of “effects of activities.”

Review: Definition of EIAEnvironmental 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.

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

timeImpact at different

scale

Important Considerations for Impact Prediction

1. Baseline condition2. Uncertainty3. Spatial limits4. Temporal boundaries5. Incremental condition 

METHODS OF IMPACT PREDICTION

1. EXTRAPOLATIVE METHODS2. NORMATIVE METHODS

ANOTHER METHOD FOR IMPACT PREDICTION

1. MATHEMATICAL MODEL2. STATISTICAL MODELS3. GEOGRAPHY INFORMATION SYSTEM4. FIELD AND LABORATORY EXPERIMENTAL METHODS5. PHYSICAL MODELS 6. EXPERT JUDGMENTS

EXTRAPOLATIVE METHODS

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).

NORMATIVE METHODS

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.

MATHEMATICAL MODEL

• 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).

TYPES OF MATHEMATICAL METHODS

1. DETERMINISTIC MODELS2. STOCHASTIC MODEL

STATISTICAL MODELSStatistical analysis are sometimes used to indicate the relationship between the data and test hypothesis,

For example, in predicting flood frequencies.

GEOGRAPHY INFORMATION SYSTEM (GIS)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 AND LABORATORY EXPERIMENTAL METHODS

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.

PHYSICAL MODELSThese 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.

EXPERT JUDGMENTS

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, andd) Be adaptable.

Method Advantages Disadvantages Checklists easy to understand and use

good for site selection and priority setting simple ranking and weighting

do not distinguish between direct and indirect impacts

do not link action and impact the process of incorporating values can be

controversial

Matrices link action to impact good method for displaying EIA results

difficult to distinguish direct and indirect impacts

have potential for double-counting of impacts

Networks link action to impact useful in simplified form for checking for

second order impacts handles direct and indirect impacts

can become very complex if used beyond simplified version

Overlays easy to understand focus and display spatial impacts good siting tool

can be cumbersome poorly suited to address impact duration or

probability

GIS and computer

expert systems

excellent for impact identification and spatial analysis

good for ‘experimenting’

heavy reliance on knowledge and data often complex and expensive

Main advantages and disadvantages of impact identification methods:

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; and• availability of mitigation practice and technology to ameliorate

impacts.

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 TECHNIQUES2. 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 yearshealth damage of the society * * **Environmental Cost environmental damage * ** ***emission trading scheme - - ***

Benefit Criteria WIND-FARM POWER GENERATOR COAL-FIRED POWER GENERATORCentralized

GeneratorDistributed 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 or deterioration 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…