ENVS402 – Environmental Impact Assessment
Chapter 6: Executing the EIA Process
6.3 Methods of Identifying Impacts
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Methods of identifying impactsMethods of identifying impacts(Ref. Lary W Canter, 1996, Environmental Impact Assessment. Mc Graw Hill international Editions, Civil Engineering Series, page. 56-101)101)
Matrices Networks Checklists Overlay M iMapping
Simple Network Simple Map
Stepped Descriptive
Others Scaling
Questionnaire
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Methods of identifying impactsMethods of identifying impacts1.1 Simple Matrices
Th i t ti t i th d d l d b• The interaction‐matrix method developed by Leopold et al. (1971) will be used as an example.
• The matrix lists approx. 100 specified actions and 90 environmental items.
Actions causing impacts
MIEnvironmental Items IEnvironmental Items
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Figure: Leopold Matrix, M= Magnitude; I= Importance
Methods of identifying impactsMethods of identifying impacts
1.1 Simple Matrices• Example of Actions and Environmental items in Leopold Interaction Matrix.
Actions causing impacts (category):
Environmental Factors (Category):
1. Modification of regime2. Land transformation
and construction3 Resource extraction
(Category):A. Physical and chemical
characteristics (Earth, Water, Atmosphere, Processes)
B Bi l i l diti
MI
3. Resource extraction4. Processing5. Land alteration6. Resource renewal7. Changes in traffic8 W t l t
B. Biological conditions (Flora, Faun)
C. Cultural factors (Land use, Recreation, Aesthetics and human
8. Waste emplacement and treatment
9. Chemical treatment10. Accidents11. Others
interests, Cultural interests, Manufactured facilities and activities)
D. Ecological relationshipsE Others Leopold Matrix M= Magnitude; I= Importance
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E. Others Leopold Matrix, M= Magnitude; I= Importance
Methods of identifying impactsMethods of identifying impacts1.2 Concept of Stepped Matrices:1 A d i i l ll d “ i1. A stepped matrix is also called “cross‐impact
matrix” can be used to address secondary and tertiary impacts of initiating actionstertiary impacts of initiating actions.
2. A “stepped matrix” is one in which environmental factors are displaced against p gother environmental factors.
3. The consequences of initial changes in some factors on other factors can be displayed.
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Methods of identifying impacts
Concept of Stepped Matrix
ACTIONS
1 2 3 4 5
A
A B F G H
FACT
ORS
A
B
C
F
D
E
F
A
B
H
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I
J
Leopold matrix showing Magnitude and Intensity on scale of 1 to 10
A ti itiA ti iti AdverseAdverse NoNo BeneficialBeneficial
Simple matrixActivitiesActivities Adverse Adverse
effecteffectNo No EffectEffect
Beneficial Beneficial EffectEffect
Land transformation & CompactionLand transformation & Compaction
Land UseLand Use
Water ResourcesWater Resources
Air qualityAir quality
Noise & VibrationNoise & Vibration
Transportation systemsTransportation systems
O h T f M iO h T f M iOther Type of MatricesOther Type of Matrices
1. Modified Graded matrix (Lohani and Than)
2. Environmental Compatibility matrix
3. Impact Summary matrix
Environmental Compatibility
Matrix for Upper BhotekoshiBhotekoshi Hydropower
projectproject
Decision Matrix forMatrix for
Upper Bhotekosi
Environmental Impact Matrix of Arun – III Hydro Project – A Part of Impact Summary Matrix
Environmental Impact Matrix of Arun – III Hydro Project – A Part of Impact Summary Matrix
Methods of identifying impactsMethods of identifying impacts2. NETWORKS
“Networks” are those methodologies which integrate impact causes and consequencesintegrate impact causes and consequences through identifying interrelationships between casual actions and the impacted penvironmental factors, including those representing secondary and tertiary effects.
- Larry W. Canter, 1996, page 81
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Methods of identifying impactsMethods of identifying impacts2. NETWORKS
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Use of Networks method in road sector example
Rural road project
Land and soil
Forests Air and water
Conversion of Loss of forest Emission of airConversion of arable land due to road construction
Loss of forest area/species
habitat
Emission of air pollutants discharge
Decline in Soil erosion
and Flooding and siltation,
change in river crops
production downstream
sedimentation
ghydrology changes
Loss of endemic or protected or endangered
Change in microclimate, decline in
aquatic or terrestrial p gspecies
qproductivity
Migration
Change in productivity of
terrestrial, ti d
Change in employment t iti d lit
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aquatic and manmade
system
opportunities and quality of life
Methods of identifying impactsMethods of identifying impacts
Simple listsSimple lists1.1. Simple listsSimple lists
2.2. Descriptive checklistsDescriptive checklists
3.3. Scaling checklistsScaling checklists
Questionnaire checklistQuestionnaire checklist4.4. Questionnaire checklistQuestionnaire checklist
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Methods of identifying impactsMethods of identifying impactsS.N Environmental Component Sub‐component
1. Physical LandlandscapeLand use
1 Simple
Water resourcesAir and noise
2. Biological and agricultureWildlifeAquatic life1. Simple
ChecklistBirdsBiodiversityHabitat
3. Human, social, Goods and servicesIrrigation and agriculture production
economic, and cultural and religious (including
Drinking water, health and sanitationHuman capitalSocial capitalAccidents and occupational safetyPrivate properties/infrastructure and public
gender, ethnicity, ) utility structuresLivelihoodsEmploymentIncomeArchaeologicalh / d
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Chautara, pati/pauwaa, monument graveyard;temple, shrine
Methods of identifying impactsMethods of identifying impacts
2. Descriptive Checklistp
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Methods of identifying impactsMethods of identifying impacts3. Scaling Checklist
F IFactors Impact Beneficial impact
1 2 3 Adverse impact
1 2 3 Habitat quality
SpeciesSpecies
Size/abundance
Duration
Reversibility
Magnitude
1= low; 2=medium; and 3=high
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4. Questionnaire Checklist
1. Might the project affects any protected area? -------------NO --------------------YESIf YES specify which area in what ways (direct indirect) nature of the impact (short or long-If YES specify which area, in what ways (direct, indirect), nature of the impact (short or long-term, reversible or irreversible, cumulative, synergistic), and severity. ………………..…………………………………………………………………………………………………………
2. Will the project site locate near the valuable forests? -------------------No ----------------YESIf YES, identify the forests, their value and describe possible direct and indirectconsequences of project…………………………………………………………………………………………………………
1. Will the project locate existing landslides or landslides and erosion prone areas, and henceincrease the slope instability, landslides and erosion? -----------------NO -------------YESp y,If YES specify the sites, and explain how. ……………………. ………………….……………………..
2. Might the project disrupt natural drainage pattern? …………….NO ……………YESIf YES specify the location and potential consequencesIf YES specify the location and potential consequences.
Overlay MappingOverlay Mapping
• Overlay mapping is a• Overlay mapping is a simple technique for displaying the impact areas
• The resources likely are to be impacted and pintensity of impacts can be presented through color shadingcolor shading
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ConclusionConclusion
In the history of EIA, an enormous variety of methods have been devised to help undertake EIAs and prepare EIA reports.
These EIA methods are structured which allow impact to be identified, manipulated and presented.
Some methods are suited to one of these tasks, whereas other methods for all of them.
These EIA methods are tools used to assist EIA implementation.They should be modified, adapted, extended or simplified to meet the needs of a particular EIA.
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