ENVIRONMENTAL IMPACT IDENTIFICATION METHODOLOGIES

S.M. Shiva Nagendra, Ph.D.Department of Civil Engineering

Environmental Water Resources Division INDIAN INSTITUTE OF TECHNOLOGY MADRAS

Chennai -600 036http://www.iitm.ac.in

CE6180:EIA- Lecture 10

EIA PROCESS

• A logical and systematic approach needs to be considered forenvironmental impact assessment. The method should take into accountof all of the important environment/project impacts and interactions,indirect and cumulative effects, which may be potentially significant, arenot inadvertently omitted.

• The most common methods used in EIA are :

• adhoc (professional judgment)• checklists• matrices• networks• overlays and geographic information systems (GIS)• expert systems

EIA METHODOLOGIES

CHOICE OF EIA METHODS

• The type and size of proposal

• The type of alternatives being considered

• The nature of the likely impacts

• The availability of impact identification methods

• The experience of the EIA team

• The resources available (time, cost, information, personnel)

EIA METHODOLOGIES

CRITERIA FOR THE SELECTION OF EIA METHODOLOGIES

1. GENERAL

a). Simplicity:The methodology should be simple so that the availablemanpower with limited background knowledge can graspand adopt it without much difficulty.

b). Manpower Time and Budget Constraints :The methodology should be applied by a small groupwith a limited budget and under time constraints.

c). Flexibility:The methodology should be flexile enough to allow fornecessary modifications and changes through the courseof the study.

2. IMPACT IDENTIFICATION

a) Comprehensiveness:

The methodology should be sufficiently comprehensive tocontain all possible options and alternatives and should giveenough information on them to facilitate proper decision –making

b) Specificity:

The methodology should identify specific parameters onwhich there would be significant impacts.

EIA METHODOLOGIES

c). Isolation of project impacts:

The methodology should suggest procedures for identifyingproject impacts as distinguished from future environmentalchanges produced by other causes.

d). Timing and duration:

The methodology should be able to identify accurately thelocation and extent of the impacts on a temporal scale

EIA METHODOLOGIES

3. IMPACT MEASUREMENT:

a). Commensurate units:

The methodology should have a commensurate set ofunits so that comparison can be made betweenalternative and criteria.

b). Explicit indicators:

The methodology should suggest specific and measurableindicators to be used to qualify impacts on the relevantenvironmental parameters.

EIA METHODOLOGIES

c). Magnitude:

The methodology should provide for the measurement ofimpact magnitude, defined as the degree of extensivenessof scale of the impact, as distinct from impact importance,defined as the weighting of the degree of significanceof the impact.

d). Objective Criteria:

It should be based on objective criteria and the criteriashould be stated explicitly.

EIA METHODOLOGIES

4. 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 impactsignificance should be explicitly stated.

c). Portrayal of with and without situation: The methodology should be able to aggregate the vastamounts of information and raw input data.

EIA METHODOLOGIES

d). Uncertainty: Uncertainty of possible impacts is a very real problem inenvironmental impact assessment. The methodologyshould be able to take this aspect into account.

e). Risk : The methodology should identify impact that have lowprobability of occurrence but a high potential for damageand loss.

f). Depth of Analysis: The conclusions derived from the methodology should beable to provide sufficient depth of analysis and instillconfidence in the users, including the general public.

EIA METHODOLOGIES

g). Alternative Comparison:

It should provide a sufficiently detailed and completecomparison of the various alternatives readilyavailable for the project understudy.

h). Public involvement:

The methodology should suggest a mechanism for publicinvolvement in the interpretation of the impacts and thesignificance.

EIA METHODOLOGIES

5. IMPACT COMMUNICATION

a). Affected parties: The methodology should provide mechanism for linkingimpacts to specific effected geographical or social groups.

b). Setting description:It should provide description of a project setting to aid theusers in developing an adequately comprehensive overallperspective.

c). Summary format: It should provide the results of the impact analysissummarized in a format that will give the users, who rangefrom the lay public to the decision makers, sufficientdetails to understand it and have confidence in itsassessments.

EIA METHODOLOGIES

d). Key issues: It should provide a format for highlighting the key issuesand impacts identified in the analysis.

e). Compliance:One of the most important factors in choosing amethodology is whether it is able to comply with the termsof reference established by the controlling agency.

EIA METHODOLOGIES