Environmental Impact

Assessment (EIA)
and
Mitigation Measures
 Lecture Topics
• Environmental Parameters
• Potential Impact on Infrastructure Development
Projects
– Thana Road Project
– Thana Irrigation Schemes
– Thana Drainage and Embankment Projects
• Environmental Impact Assessment (EIA)
• Environmental Protection Measures
 Environmental Parameters
It can be grouped into major three components.

ECOLOGY

PHYSICO-
CHEMICAL HUMAN
INTEREST
 Ecology
• Aquatic  Terrestrial
– Fisheries  Forest
– Eutrophication  Wildlife
– Aquatic weeds  Species diversity
– Species diversity  Endangered species
– Endangered species
 Physico-chemical
• Land
 Groundwater
– Erosion and siltation
 Regional hydrology
– Backwater effect
 Recharge
– Bank stability
 Water table
– Drainage
 Water pollution
– Soil characteristics
• Surface water
 Atmosphere
– Regional hydrology
 Air pollution
– Silt load
 Dust pollution
– Water pollution
 Noise pollution
 Human Interest
 Socio-Economic
 Land Loss
 Crop Production
• Health
 Aquaculture
– Diseases  Irrigation
– Sanitation  Navigation
 Flood Control
– Nutrients  Transport
• Aesthetic  Re-settlement
 Employment
– Landscape  Agro-industrial
– Recreation
Potential Impacts on Environment

• A change in system exerts certain influence on many

different environmental parameters resulting a net
positive or negative impact on the environment.

• Impact on major Infrastructure development projects

such as:
– Thana road projects
– Thana irrigation schemes
– Thana drainage and embankment projects
 Ecological Impact

Fisheries
• (a) Fisheries:
– (-) Roads prevent longitudinal and lateral
migration of fishes in the flood plain
– (-) Obstruct movement of fishes onto
natural feeding and breeding grounds in
the flood plain. Fish breeding ground
• (b) Forest:
– (-) Roads running through forest area and
plantations may be the cause of
destruction of trees in the forest and
alteration of ecology of the forest.

Road running through forest

 Ecological Impact

• (c) Plantation:
– (+) The roadsides may be used for Roadside plantation
plantation of trees which has favorable
impact of road construction.
• (d) Wetland and Wetland Habitant:
– (-) The road may encroach wetlands
which may alter the ecology of
wetlands and may cause destruction
of wetland habitat.
• (e) Nuisance Plant/Eutrophication: wetland
– (-) The Roads running through forest
area and plantations may be the cause
of destruction of trees in the forest
and alteration of ecology of the forest.

Eutrophication
 Physico-chemical Impact

• (a) Erosion and Siltation

– (-) causes erosion during flood
and siltation in the downstream.
• (b) Drainage Congestion /Water
logging
– (-) roads interfere with cross Road erosion
drainage and can cause flooding
or drainage congestion in
adjacent areas during periods of
high precipitation.
– (-) May cause crop damage,
water pollution and breeding of
mosquitoes.

Road side water logging

 Physico-chemical Impact

• (c) Regional Hydrology/Flooding

– (-) Roads constructed across flood plains
perpendicular to the direction of water
flow cause back water effect and increase
duration, frequency and extent of
flooding in the up stream.
• (d) Obstruction to Waste water flow
– (-) Roads may obstruct the drainage of Road obstruction to drainage
sewage and industrial waste water
loading to serious pollution problem.
• (e) Dust /Noise Pollution
– (-) Dust raised from unpaved rural roads
and blown by the vehicles can pose a
health hazard and damage vegetation
along the sides of the road.
Dust pollution
 Impact on Human Interest

• (a) Loss of Agricultural Lands

– (-) Construction of any road is associated with
the loss of agricultural lands.
• (b) Generation of Employment
Opportunities
– (+) Construction of road generates temporary Agricultural land
employment during project implementation
and permanent employment during
maintenance phase.
• (c) Navigation and Boat Communication
– (-) Roads interference with navigation and boat
communication at least for certain period of
the year.
Road construction
 Impact on Human Interest

• (d) Commercial and Service Facilities

– (+) The thana roads provide benefit of fast communication
communication, transport facilities etc.
• (e) Industrial Activities
– (+) Road communication promotes industrial
activities.
• (f) Irrigation Facilities Borrow-pit Irrigation
– (+) Borrow-pits by the side of the roads
provide facility for small scale irrigation.
• (g) Landscape
– (-) Scattered borrow pits, unauthorized
growth around road , erosion result in marred
landscape.
Scattered borrow-pit
 Environmental Impact Assessment
(EIA)
• Assessment of the beneficial and adverse changes
in environmental resources or values resulting from
a proposed project.

• Essential Elements
1. Identification of possible positive or negative impacts of
the project.
2. Quantifying impacts with respect to common base.
3. Preparation of mitigation plan to offset the negative
impacts.
 Methods of Assessment

• Environmental Impact Value

n
EIV   (Vi )Wi
i 1

• Vi = Relative change of the environmental quality of

parameters
• Wi= Relative importance or weight or parameter
• n = total number of environmental parameters
 Quantification of
Environmental Impact

• Changes of environmental
parameters
– Severe (+5 or -5) Severe

– Higher (+4 or -4) Higher

– Moderate (+3 or -3) Moderate

– Low (+2 or -2) Low

Very low
– Very Low (+1 or -1)
No change
– No change (0)
0 1 2 3 4 5
 Relative Importance of
Environmental Parameters
• All parameters are not of equal importance or weight
[Degree of Impact]
• It varies from country to country
• In Bangladesh flood, employment, agriculture,
fisheries carry more importance.
• In next slide, a summary of relative importance of
parameters for Thana Road project is presented.
ENVIRONMENTAL PARAMETERS Relative Degree of EIV#
Importance Impact
Value
I. ECOLOGICAL -19
Fisheries 10 -2
Forest 5 0
Tree Plantation 2 +1
Wetland/Wetland Habitant 4 0
Nuisance Plant/Eutrophication 1 -1

II. PHYSICO-CHEMICAL -13

Erosion and Siltation 2 -1
Regional Hydrology/Flooding 6 -1
Drainage Congestion/Water logging 5 -1
Obstruction to Waste Water Flow 3 0
Dust Pollution/Noise Pollution 2 0

#EIV = ∑(Relative Imp. Value*Degree of Impact)

 ENVIRONMENTAL PARAMETERS Relative Degree EIV
Importance of Impact
Value
III. HUMAN INTEREST +26
Loss of Agricultural Lands 4 +2
Employment Opportunities 4 +3
Navigation/Boat Communication 3 -2
Commercial and Service Facilities 3 +2
Industrial Activities 1 +2
Irrigation Facilities 2 +3
Landscape 2 -1

Total Environmental Impact Value -4

• Changes of environmental parameters:: Higher (+4 or -4)

Adverse Environmental Impacts
and
Mitigation Measures
 1. Loss of fish breeding

• 1. Action:
– Loss of breeding, nursery and feeding
ground in flood plain.
• 1. Impact: Fish breeding
– Reduction in Fish protein consumption.
– Unemployment of fisherman.
• 1. Mitigation Measures:
– Allow controlled flooding.
– Compensate the loss by fish culture.

Fish farm
 2. Obstruction to fish migration

• 2. Action:
– Obstruction to migration of fish.
• 2. Impact:
– Same as 1.
• 2. Mitigation Measures: Fish ladder

– Provide adequate opening in roads

and embankments along routes of fish
migration.

Fish pass
 3. Uncontrolled Pesticide

• 3. Action:
– Reproduction failure and
destruction of fish by
uncontrolled use of pesticide.
• 3. Impact:
Applying Pesticide
– Same as 1.
• 3. Mitigation Measures:
– Adopt Integrated Pest
Management (IPM) for pest
control.
– Prevent drainage from
agriculture land from reaching
water bodies.
Bugs used in IPM
 4.Drying up of wetland

• 4. Action:
– Drying up of the wetlands for
agriculture purpose and
destruction of habitat for fish,
birds, amphibians etc.
• 4. Impact:
– Reduction in Fishery.
– Elimination of species of fish,
birds, amphibians etc.
– Disruption of wetland ecology.
• 4. Mitigation Measures:
– Avoid complete drying up of
wetlands and swamp land.
– Restore alternative habitat for
endangered species.

wetland
 5.Cutting trees

• 5. Action:
– Clearing of forest lands and cutting of trees
within the right-of-way of the road.
• 5. Impact:
– Reduction in forest cover. Cutting forest
– Reduction in forest products.
– Disruption of forest ecology.
• 5. Mitigation Measures:
– Find alternative route to avoid forest through
planning exercise.
– Replace the trees by plantation along road
sides. Cutting trees on road
 6.Spreading Nuisance plants

• 6. Action:
– Spreading of nuisance plants from
borrow pit.
• 6. Impact:
– Damage crops during flood.
• 6. Mitigation Measures:
– Incorporate destruction of such plants
in maintenance program.
– Convert the plants into a compost for
application as a soil
conditioner/manure. Nuisance plants
 7.Pollution from drainage

• 7. Action:
– Discharge nutrient enriched
agricultural land drainage in surface
water.
• 7. Impact:
– Causes eutrophication and surface
water pollution.
– Makes the water unsuitable for
beneficial uses.
– Destroys aquatic environment.
• 7. Mitigation Measures:
– Prevent agricultural land drainage Agriculture drainage pollution
from reaching from reaching surface
waters.
 8.Water pollution
• 8. Action:
– Reaching residues of pesticides in
surface and groundwater from
agricultural lands.
• 8. Impact:
– Cause water pollution.
– Contaminates sources of water
supply.
– Pesticides residues accumulate in
bio-mass.
• 8. Mitigation Measures:
– Reduce use of pesticides through
IPM.
– Prevent agricultural land drainage
from reaching surface water.
Agriculture runoff
 9.Erosion and Siltation

• 9. Action:
– Erosion of road and embankment surfaces and
sides, road openings, bed and banks of
rivers/canals subsequent silation in down stream.
• 9. Impact:
– Cause damage to road and embankment.
– Affect stability of road/embankment and their
structures.
– Increases turbidity of water.
Erosion of embankment
– Siltation of canal bed and agricultural lands.
• 9. Mitigation Measures:
– Select appropriate soils for road and
embankment construction.
– Compact the road materials properly.
– Provide proper slope for surface drainage and
vegetation cover.
– Provide adequate opening for discharge of flood
and accumulated rain water.
Sediment Loading
 10.Drainage congestions and
water logging
• 10. Action:
– Drainage congestion and water
logging
• 10. Impact:
– Crop damage and loss of
agricultural lands.
– Cause water pollution. Drainage canal
– Provide ground fro mosquito
breeding.
• 10. Mitigation Measures:
– Provide adequate opening for
drainage.
– Provide facilities for pumping
of congested water.

Pumping of drained water

 References

– Guidelines on environmental issues

related to physical planning, LGED, 1992.

– Environmental Impact Assessment,

CERM, BUET, 2013.