sagar725744

Dams and Development - Report of the World Commission on Dams
P.P.TP.P.T
ONON
DamsDams

Dams and reservoirsDams and reservoirs
ReservoirsReservoirs
• Site selectionSite selection
• Leakage fromLeakage from
reservoirsreservoirs
• SedimentationSedimentation
• Stability: effect ofStability: effect of
raised WTraised WT
DamsDams
• TypesTypes
• Forces on a damForces on a dam
• Geology and damGeology and dam
sitessites
• Rock types andRock types and
damsdams
• Dams on soilsDams on soils
• GroundGround
improvementimprovement

Dams and reservoirs - literatureDams and reservoirs - literature
• Bell F.G., Engineering geology andBell F.G., Engineering geology and
geotechnicsgeotechnics
– Ch 6 (Reservoirs)Ch 6 (Reservoirs)
– Ch 7 (Dams)Ch 7 (Dams)
• Blyth F.G.H. and de Freitas M.H., A geologyBlyth F.G.H. and de Freitas M.H., A geology
for engineersfor engineers
– Ch 14 (Reservoirs and dams)Ch 14 (Reservoirs and dams)

Reservoirs: purposeReservoirs: purpose
• Water storageWater storage
• Flood preventionFlood prevention
• PowerPower

Reservoirs: site selectionReservoirs: site selection
• Hydrological considerationsHydrological considerations
• Fundamental controlsFundamental controls
– topographytopography
– climateclimate
– geologygeology
WaterWater
addedadded
Net amount of waterNet amount of water
available for storageavailable for storage
WaterWater
subtractedsubtracted++
Rainfall in riverRainfall in river
basinbasin
InfiltrationInfiltration
EvaporationEvaporation
TranspirationTranspiration
RunoffRunoff

Reservoirs: leakageReservoirs: leakage
WaterWater
addedadded
Leakage fromLeakage from
reservoirreservoir
WaterWater
subtractedsubtracted--
Rainfall inRainfall in
river basinriver basin
InfiltrationInfiltration
EvaporationEvaporation
TranspirationTranspiration
Net amount of waterNet amount of water
available for storageavailable for storage
RunoffRunoff
--
1. Dam bypass1. Dam bypass
2. Water table effects2. Water table effects

Leakage via subsurface bypass due to siphon effectLeakage via subsurface bypass due to siphon effect
Devonian strataDevonian strata
DevonianstrataDevonianstrata
Devonian strataDevonian strata
Dol-y-gaer damDol-y-gaer dam
Carboniferous strata:Carboniferous strata:
Subsurface water flowSubsurface water flow
reservoir levelreservoir level
fracture and dissolutionfracture and dissolution
flow routesflow routes

Leakage buried channels beneath driftLeakage buried channels beneath drift
50 km50 km
Modern river/valleyModern river/valley
Ancient river/valleyAncient river/valley
R Drac
R Drac
SautetSautet
dam anddam and
reservoirreservoir
Bypass of reservoir in driftBypass of reservoir in drift

land surface
land surface
water table
water table
riverriver
reservoirreservoir
beforebefore
afterafter
water table dividewater table divide
Leakage to next valleyLeakage to next valley
Bedrock with a waterBedrock with a water
table and finitetable and finite
permeabilitypermeability
newnew
waterwater
tabletable
Reservoirs: water tableReservoirs: water table
leakage-1leakage-1

Land surface
Land surface
riverriver
beforebefore
Bedrock with lowBedrock with low
permeability: aquicludepermeability: aquiclude
HighHigh
layerlayer
Water table in aquiferWater table in aquifer
reservoirreservoir
afterafter
HighHigh
layerlayer
Modified water table in aquiferModified water table in aquifer
Leakage to next valleyLeakage to next valley
Reservoirs: water tableReservoirs: water table
leakage-2leakage-2

Reservoirs:Reservoirs:
sedimentationsedimentation
• World’s largest dam;World’s largest dam;
180m tall, 2km wide180m tall, 2km wide
– 84% sediment in84% sediment in
rainy season (june-rainy season (june-
sept)sept)
– drawdown anddrawdown and
sediment sluicingsediment sluicing
during this periodduring this period

BeforeBefore
Water tableWater table
riverriver
After - 1After - 1
reservoirreservoir
Raised water tableRaised water table
After - 2After - 2
reservoirreservoir
Failure andFailure and
slumpingslumping
due todue to
weakenedweakened
rock massrock mass
Reservoirs: raised waterReservoirs: raised water
tabletable

Viaont dam disaster, ItalyViaont dam disaster, Italy

Normal stressNormal stress σσnn
ShearstressShearstressσσss
σσ1,WT1,WTσσ3,3, WTWT
UnstableUnstable
StableStable
σσ11σσ33
σσss == c +c + µµ .. ((σσnn - p)- p)
p = pore fluid pressurep = pore fluid pressure
σσnn – p = effective stress– p = effective stress
Raising water tableRaising water table
Reservoirs: raised waterReservoirs: raised water
tabletable

Dams: typesDams: types
• Gravity dam: rigid monolithic structureGravity dam: rigid monolithic structure
– Trapezoidal cross sectionTrapezoidal cross section
– Minimal differential movement toleratedMinimal differential movement tolerated
– Dispersed moderate stress on valley floor andDispersed moderate stress on valley floor and
wallswalls
• Arch dam: high strength concrete wallArch dam: high strength concrete wall
– Convex faces upstreamConvex faces upstream
– Thin walled structureThin walled structure
– Relatively flexibleRelatively flexible
– Huge stresses imposed on valley walls andHuge stresses imposed on valley walls and
floorfloor
• Earth dams: bank or earth or rock withEarth dams: bank or earth or rock with
impermeable coreimpermeable core
– Core of clay or concrete, extended belowCore of clay or concrete, extended below
groundground
– Sand or gravel drains built to cut fluidSand or gravel drains built to cut fluid
pressurepressure

Types of damTypes of dam
ArchArch
GravityGravity
ButtressButtress
EmbankmentEmbankment
or Earthor Earth

Emosson Dam, SwitzerlandEmosson Dam, Switzerland

The Vaiont dam todayThe Vaiont dam today

Dams: forces appliedDams: forces applied
• Vertical static forcesVertical static forces
• Lateral force applied by water bodyLateral force applied by water body
• Dynamic forcesDynamic forces
– wave actionwave action
– overflow of water (controlled by spillwayoverflow of water (controlled by spillway
channels)channels)
– earthquakes and tremorsearthquakes and tremors
– ice/freezingice/freezing

Dam failure: earthquakeDam failure: earthquake

Dam failure: asteroidsDam failure: asteroids

Dam failure: bombsDam failure: bombs

Poor geological characterisation of dam foundationPoor geological characterisation of dam foundation
responsible for 40% of dam failuresresponsible for 40% of dam failures
Need proper site investigationNeed proper site investigation
Dam sites: geologyDam sites: geology

Poor geological conditions can be improved in 2 waysPoor geological conditions can be improved in 2 ways
• improving load bearing propertiesimproving load bearing properties
• controlling seepagecontrolling seepage
gravelgravel sandsand siltsilt clayclay
>10>10 22 0.070.07 0.0020.002 <0.0001 mm grain size<0.0001 mm grain size
Rolling, bolting and pre-loadingRolling, bolting and pre-loading
gravity drainagegravity drainage
well-points with drainagewell-points with drainage
electro-osmosiselectro-osmosis
vibro flotationvibro flotation
explosivesexplosives
groutsgrouts
chemical treatmentschemical treatments
thermal treatmentthermal treatment
groundstrengtheninggroundstrengthening Dams: groundDams: ground

Dams: groundDams: ground
• Rock boltsRock bolts
• Rolling and preloadingRolling and preloading
– compresses ground in prep for structurecompresses ground in prep for structure
– improves post dam compactionimproves post dam compaction
• Gravity drainage and well points:Gravity drainage and well points:
– sand and gravel channels and shallow wells (for pumping) Electro-osmosis: insertsand and gravel channels and shallow wells (for pumping) Electro-osmosis: insert
conduction rods into fine grained clay-rich bedrock and have an electric field - de-conduction rods into fine grained clay-rich bedrock and have an electric field - de-
waters ground via the flow of electric currentwaters ground via the flow of electric current
• VibroflotationVibroflotation
– mechanical vibrating plate with load compresses low density gravels and sandsmechanical vibrating plate with load compresses low density gravels and sands
• ExplosivesExplosives
– useful in water-saturated gravel and scree – increases bulk densityuseful in water-saturated gravel and scree – increases bulk density
• GroutsGrouts
– material injected into the groundmaterial injected into the ground
• Chemical treatmentsChemical treatments
– react solutions injected into ground. React with material to alter properties. NaClreact solutions injected into ground. React with material to alter properties. NaCl
solution injected into smectite-rich mud, shale etc. to alter expansivity of smectite –solution injected into smectite-rich mud, shale etc. to alter expansivity of smectite –
stabilizes ground pre-constructionstabilizes ground pre-construction
• Thermal treatmentThermal treatment
– FreezingFreezing with injected liquid N2 to consolidate loose ground during excavation.with injected liquid N2 to consolidate loose ground during excavation.
HeatingHeating by burning petroleum under pressure in subsurface – causes thermalby burning petroleum under pressure in subsurface – causes thermal
metamorphism - hardens ground and cuts porositymetamorphism - hardens ground and cuts porosity

InjectedInjected
grout curtaingrout curtain
Pre-stressedPre-stressed
anchorsanchors
DrainDrain
Apron drains (toApron drains (to
individual aquifers)individual aquifers)
ExcavationExcavation
to rockto rock
RegolithRegolith
ReservoirReservoir
Ripraptokill
Ripraptokill
waveenergy
waveenergy
Hard face to damHard face to dam
Aquifer layersAquifer layers
Aquiclude layersAquiclude layers
Core and rear of damCore and rear of dam

• In Turkey, 536 large dams have been built andIn Turkey, 536 large dams have been built and
being operated. On the other hand, Smallbeing operated. On the other hand, Small
Hydraulic Works Department has built 42 smallHydraulic Works Department has built 42 small
dams.dams.
• Here, 50 storage facilities that are not consideredHere, 50 storage facilities that are not considered
as dam due to their low heights (<15m) and lowas dam due to their low heights (<15m) and low
storage capatcities (<2 hmstorage capatcities (<2 hm33
) have not been taken) have not been taken
into account.into account.
• By now, construction of 100 dams andBy now, construction of 100 dams and
hydroelectric powerplants is going on.hydroelectric powerplants is going on.

DefinitionDefinition
• A dam is a structure which prevents the flowA dam is a structure which prevents the flow
of water and accumulates it in a reservoirof water and accumulates it in a reservoir
Karakaya Dam/DiyarbakırKarakaya Dam/Diyarbakır Atatürk Dam/ŞanlıurfaAtatürk Dam/Şanlıurfa

Needs for Dam ConstructionNeeds for Dam Construction
1.1. Drinking and domestic water supplyDrinking and domestic water supply
2.2. Flood controlFlood control
3.3. IrrigationIrrigation
4.4. Industrial water supplyIndustrial water supply
5.5. Hydroelectric energy productionHydroelectric energy production
6.6. Retention and control of sedimentsRetention and control of sediments
and Inland navigation, Improvement of water quality,and Inland navigation, Improvement of water quality,
Fish Farming, Recreation facilitiesFish Farming, Recreation facilities

BREAKDOWNBREAKDOWN byby PURPOSEPURPOSE ofof DAMSDAMS inin EUROPEEUROPE

CLASSIFICATION OF DAMSCLASSIFICATION OF DAMS

ACCORDING to the SIZE of theACCORDING to the SIZE of the
DAMDAM
1.1. Large (Big) damLarge (Big) dam
2.2. Small damSmall dam
• International Commision on Large Dams, (ICOLD) assumes a damInternational Commision on Large Dams, (ICOLD) assumes a dam
as big when its height is bigger than 15m.as big when its height is bigger than 15m.
• If the height of the dam is between 10m and 15m and matches theIf the height of the dam is between 10m and 15m and matches the
following criteria, then ICOLD accepts the dam as big:following criteria, then ICOLD accepts the dam as big:
• If the crest length is bigger than 500mIf the crest length is bigger than 500m
• If the reservoir capacity is larger than 1 million mIf the reservoir capacity is larger than 1 million m33
• If the flood discharge is more than 2000 mIf the flood discharge is more than 2000 m33
/s/s
• If there are some difficulties in the construction of foundationIf there are some difficulties in the construction of foundation

ACCORDING to HEIGHT ofACCORDING to HEIGHT of
DAMDAM
• High Dam or Large DamHigh Dam or Large Dam
• If the height of the dam is bigger than 100mIf the height of the dam is bigger than 100m
• Medium DamMedium Dam
• If the height of the dam is between 50m andIf the height of the dam is between 50m and
100m100m
• Low Dam or Small DamLow Dam or Small Dam
• If the height of the dam is lower than 50mIf the height of the dam is lower than 50m

ACCORDING to the STATICALACCORDING to the STATICAL
DESIGN of DAM BODYDESIGN of DAM BODY
• Gravity Dams (Sarıyar, Çubuk I, Kemer, Sır IIGravity Dams (Sarıyar, Çubuk I, Kemer, Sır II
Karacaören II)Karacaören II)
• Arch Dams (Gökçekaya, Karakaya,Arch Dams (Gökçekaya, Karakaya,
Oymapınar, Gezende)Oymapınar, Gezende)
• Butress Dams (Elmalı II)Butress Dams (Elmalı II)
• Embankment Dams (Atatürk, Seyhan, Aslantaş)Embankment Dams (Atatürk, Seyhan, Aslantaş)
• Composite Dams (Keban)Composite Dams (Keban)

GRAVITY DAMSGRAVITY DAMS
 Gravity DamsGravity Dams use their triangular shape and the sheer weightuse their triangular shape and the sheer weight
of their rock and concrete structure to hold back the water inof their rock and concrete structure to hold back the water in
the reservoir.the reservoir.
Sarıyar Dam – Sakarya River;Sarıyar Dam – Sakarya River;
Height= 90 mHeight= 90 m
Reservoir Capacity= 1.9 billion mReservoir Capacity= 1.9 billion m33

ARCH DAMSARCH DAMS
 Arch DamsArch Dams utiliutilizze the strength of an arch to displace the loade the strength of an arch to displace the load
of water behind it onto the rock walls that it is built into.of water behind it onto the rock walls that it is built into.
Karakaya Dam – Fırat River;Karakaya Dam – Fırat River;
Height= 173 mHeight= 173 m
Reservoir Capacity= 9,5 billion mReservoir Capacity= 9,5 billion m33

BUTRESS DAMSBUTRESS DAMS
 Buttress DamsButtress Dams use multiple reinforced columns to support ause multiple reinforced columns to support a
dam that has a relatively thin structure. Because of this,dam that has a relatively thin structure. Because of this,
these dams often use half as much concrete as gravity damsthese dams often use half as much concrete as gravity dams
Elmalı II – Göksu River;Elmalı II – Göksu River;
Height= 42.5 mHeight= 42.5 m
Reservoir Capacity= 10 million mReservoir Capacity= 10 million m33

EMBANKMENT DAMSEMBANKMENT DAMS
(Rock Fill or Earth Fill Dams)(Rock Fill or Earth Fill Dams)
• They are mostly composed of natural materials suchThey are mostly composed of natural materials such
as, clay, sand, gravel etc...as, clay, sand, gravel etc...
• Impervious core is placed in the middle of theImpervious core is placed in the middle of the
embankment bodyembankment body
• Generally riprap is used to control erosionGenerally riprap is used to control erosion
Atatürk Dam – Fırat River;Atatürk Dam – Fırat River;
Height= 169 m;Height= 169 m;
Reservoir Capacity= 48,7 billion mReservoir Capacity= 48,7 billion m33

COMPOSITE DAMSCOMPOSITE DAMS
• Composite dams are combinations of one or more damComposite dams are combinations of one or more dam
types. Most often a large section of a dam will be eithertypes. Most often a large section of a dam will be either
an embankment or gravity dam, with the sectionan embankment or gravity dam, with the section
responsible for power generation being a buttress orresponsible for power generation being a buttress or
arch.arch.
Keban Dam – Fırat River;Keban Dam – Fırat River;
Height= 163 m;Height= 163 m;
Reservoir Capacity= 31 billion mReservoir Capacity= 31 billion m33
Gravity & Rock FillGravity & Rock Fill

ENGINEERING GEOLOGICALENGINEERING GEOLOGICAL
STUDIES for DAM CONSTRUCTIONSTUDIES for DAM CONSTRUCTION

1. RECONNAISSANCE STUDY1. RECONNAISSANCE STUDY
1.1. Evaluation of the data having at archives of MTA, DSI, EIE,Evaluation of the data having at archives of MTA, DSI, EIE,
Universities,......etcUniversities,......etc
2.2. Field investigation for limited time (Reconnaissance Study)Field investigation for limited time (Reconnaissance Study)
3.3. Some maps in small scale, for example 1/25.000 or 1/50.000Some maps in small scale, for example 1/25.000 or 1/50.000
4.4. Some hydraulic data aboutSome hydraulic data about
a.a. BasinBasin
b.b. Precipitation areaPrecipitation area
c.c. Runoff, maximum discharge {Q=R/t (mRunoff, maximum discharge {Q=R/t (m33
/s)}/s)}
d.d. Modulus of Runoff (R/t/mModulus of Runoff (R/t/m22
~ R/t/km~ R/t/km22
))
5.5. Some approach to the reservoir area, dam site and type of damSome approach to the reservoir area, dam site and type of dam
and height of dam...etcand height of dam...etc
6.6. Photogeological studiesPhotogeological studies
7.7. A preliminary reportA preliminary report

2. PRELIMINARY STUDIES at the2. PRELIMINARY STUDIES at the
RESERVOIR AREA and DAM SITERESERVOIR AREA and DAM SITE
1.1. Dam site investigationsDam site investigations
1. Location of dam axis1. Location of dam axis
2. Location of diversion tunnel2. Location of diversion tunnel
3. Location of spillway3. Location of spillway
4. Location of powerhouse...etc4. Location of powerhouse...etc
1.1. Geological studiesGeological studies
2.2. Geophysical surveyingGeophysical surveying
3.3. Underground investigationsUnderground investigations
1. Boreholes1. Boreholes
2. Investigation galleries2. Investigation galleries
3. Pitholes3. Pitholes
1.1. Surveying for materialsSurveying for materials
1. Field surveying1. Field surveying
2. Laboratory tests2. Laboratory tests

6.6. Slope stability investigationsSlope stability investigations
7.7. Earthquake hazard & risk analysisEarthquake hazard & risk analysis
8.8. Environmental studiesEnvironmental studies
9.9. Leakage possibilities from reservoir areaLeakage possibilities from reservoir area
10.10. Leakage possibilities from dam siteLeakage possibilities from dam site
11.11. Erosion, sedimentation & siltationErosion, sedimentation & siltation

DETAILED INVESTIGATION atDETAILED INVESTIGATION at
DAM SITEDAM SITE
1.1. Topographic surveyingsTopographic surveyings
2.2. Geological mappingsGeological mappings
1/5000 – 1/1000 or 1/5001/5000 – 1/1000 or 1/500
3.3. Underground explorationsUnderground explorations
Boreholes, adits....etcBoreholes, adits....etc
4.4. Hydrogeological studiesHydrogeological studies
5.5. Slope stability analysisSlope stability analysis

FACTORS AFFECTING to the DAMFACTORS AFFECTING to the DAM
TYPE SELECTIONTYPE SELECTION
• TopographyTopography
• GeologyGeology
• Bearing capacity of the underlying soilBearing capacity of the underlying soil
• Foundation settlementsFoundation settlements
• Permeability of the foundation soilPermeability of the foundation soil
• Material availabilityMaterial availability
• Spillway positionSpillway position
• EarthquakesEarthquakes
• SafetySafety
• HeightHeight
• Aesthetic viewAesthetic view
• Qualified labourQualified labour
• CostCost

FACTORS AFFECTING to theFACTORS AFFECTING to the
PLACE of the DAM AXISPLACE of the DAM AXIS
• TopographyTopography
• GeologyGeology
• MaterialsMaterials
• Spillway location availabilitySpillway location availability
• DerivationDerivation
• Sediments in the flowing waterSediments in the flowing water
• Water qualityWater quality
• Expropriation costsExpropriation costs
• Earthquake possibilityEarthquake possibility
• Downstream water rightsDownstream water rights

RIVER BASINS in TURKEYRIVER BASINS in TURKEY
Turkey has been separated into 26 main river basins for theTurkey has been separated into 26 main river basins for the
hydrological studies.hydrological studies.

ENVIRONMENTALENVIRONMENTAL
IMPACTS OF DAMSIMPACTS OF DAMS

ENVIRONMENTAL IMPACTS ofENVIRONMENTAL IMPACTS of
CONSTRUCTION PHASE of DAMSCONSTRUCTION PHASE of DAMS
• River pollutionRiver pollution
• ErosionErosion
• Loss of aesthetic viewLoss of aesthetic view
• Air pollutionAir pollution
• Noise pollutionNoise pollution
• DustDust

ENVIRONMENTAL IMPACTS ofENVIRONMENTAL IMPACTS of
RESERVOIRSRESERVOIRS
• Loss of landLoss of land
• Habitat Destruction :Habitat Destruction :
• The area that is covered by the reservoir is destroyed, killingThe area that is covered by the reservoir is destroyed, killing
whatever habitat existed there beforehand.whatever habitat existed there beforehand.
• Loss of archeological and histrorical placesLoss of archeological and histrorical places
• Loss of mineral depositsLoss of mineral deposits
• Loss of special geological formationsLoss of special geological formations
• Aesthetic view reductionAesthetic view reduction
• SedimentationSedimentation
• Change in river flow regime and flood effectsChange in river flow regime and flood effects
• Reservoir induced seismicityReservoir induced seismicity
• Change in climate and plant speciesChange in climate and plant species

EFFECTS of DAMS to WATEREFFECTS of DAMS to WATER
QUALITYQUALITY
• Change in temperatureChange in temperature
• TurbidityTurbidity
• Dissolved gases in the waterDissolved gases in the water
• Water discharged from the spillway contains 110-120%Water discharged from the spillway contains 110-120%
saturated nitrogen. This amount may be destructive forsaturated nitrogen. This amount may be destructive for
fish life.fish life.
• EutrophicationEutrophication
• It means increase in vegetation. If moss and other plantsIt means increase in vegetation. If moss and other plants
exist in water, quality of that water gets worse.exist in water, quality of that water gets worse.

SOME DAMS from SPACESOME DAMS from SPACE

Why a World Commission on Dams ?Why a World Commission on Dams ?
In response to escalating conflictsIn response to escalating conflicts
over the role of dams inover the role of dams in
development, all constituentsdevelopment, all constituents
came together to establishcame together to establish
the Commissionthe Commission

Dam projects increasingly questioned …Dam projects increasingly questioned …
• affected populationsaffected populations
strongly oppose damsstrongly oppose dams
• proponents point toproponents point to
urgent developmenturgent development
demandsdemands
• opponents point toopponents point to
adverse impactsadverse impacts
• uprisings againstuprisings against
globalizationglobalization
• little space forlittle space for
constructive dialogueconstructive dialogue

Purposes of large damsPurposes of large dams
• Hydropower
• Irrigation
• Water supply
• Flood control
• Multipurpose

Types of large damsTypes of large dams
• Reservoir-type storage
– impound water behind the
dam for seasonal,annual
and, in some cases, multi-
annual storage and
regulation of the river.
• Run-of-river dams
– weirs and barrages, and
diversion dams create a
hydraulic head in the river to
divert some portion of the
river flows to a canal or
power station.

By 1925, falling water generated 40% of electricBy 1925, falling water generated 40% of electric
power. Today, large dams (15 m +) generate 19%power. Today, large dams (15 m +) generate 19%
of electricity.of electricity.
Hydro production capacity has grown 15 x.Hydro production capacity has grown 15 x.
Fossil fuel use has risen so rapidly that currently, hydroelectricFossil fuel use has risen so rapidly that currently, hydroelectric
only supplies one-quarter of electrical generation.only supplies one-quarter of electrical generation.
One-third of world’s countries rely on hydropower forOne-third of world’s countries rely on hydropower for
more than half their electricity supply.more than half their electricity supply.
HydropowerHydropower

Irrigation: The Aral SeaIrrigation: The Aral Sea
• Once the 4th largest inland
body of water in the world
A series of dams was built to
irrigate cotton.
• Aral Sea reduced to about
25% of its 1960 volume,
quadrupled the salinity of the
lake and wiped out the
fishery. Pollutants became
airborne as dust, causing
significant local health
problems.
• The environmental damage
caused has been estimated
at $1.25 -$2.5 billion a year.

Water suppliesWater supplies
• freshwater withdrawals doubled in 50 yearsfreshwater withdrawals doubled in 50 years
• 1 billion lack freshwater &1 billion lack freshwater &
2 billion lack electricity2 billion lack electricity
• competition for water increasingcompetition for water increasing
• aquatic ecosystems are decliningaquatic ecosystems are declining
& wetlands have been lost& wetlands have been lost

Major investments …Major investments …
• 45,000 large dams worldwide45,000 large dams worldwide
• 2 dams commissioned2 dams commissioned
per day in1970sper day in1970s
• total investment exceedstotal investment exceeds
$2 trillion$2 trillion
• $40 billion expenditure$40 billion expenditure
per year at peakper year at peak
• estimated 40 – 80 million people displacedestimated 40 – 80 million people displaced
• flow in 60% of world’s rivers affectedflow in 60% of world’s rivers affected
2 000
0
4 000
6 000
Number Of Dams
1900 1990s

Dam Drawbacks to Human CommunitiesDam Drawbacks to Human Communities
Human DisplacementHuman Displacement
Flooding of Cultural SitesFlooding of Cultural Sites
(Archeological and Modern)(Archeological and Modern)
Social disruptionSocial disruption
Cost overrunsCost overruns
Socio-economic centralizationSocio-economic centralization

Dam Drawbacks to the EnvironmentDam Drawbacks to the Environment
Ecosystem DestructionEcosystem Destruction
Fish Blockage and Wildlife LossesFish Blockage and Wildlife Losses
Large-Scale Flooding Due to Dam FailuresLarge-Scale Flooding Due to Dam Failures
Sedimentation and SalinitySedimentation and Salinity
Herbicide and Other Toxic ContaminationHerbicide and Other Toxic Contamination
Evaporative LossesEvaporative Losses
Nutrient Flow RetardationNutrient Flow Retardation
Release of greenhouse gassesRelease of greenhouse gasses

Dam AlternativesDam Alternatives
Low-Head HydropowerLow-Head Hydropower - Extract energy from small- Extract energy from small
headwater dams.headwater dams.
Run-of-River FlowRun-of-River Flow - Submerged directly in stream- Submerged directly in stream
and usually do not require dam or diversionand usually do not require dam or diversion
structure.structure.
Micro-Hydro GeneratorsMicro-Hydro Generators - Small versions designed- Small versions designed
to supply power to single homes.to supply power to single homes.

WCD FindingsWCD Findings
• Dams have made a significant contributionDams have made a significant contribution
• A considerable number have fallen below targetsA considerable number have fallen below targets
• EEconomic and financialconomic and financial under-under-performanceperformance
• Significant impacts on riverineSignificant impacts on riverine &&
downstream ecosystemsdownstream ecosystems
• Heavy toll on affected communitiesHeavy toll on affected communities
• AAlternativeslternatives oftenoften existexist
• Lack ofLack of compliancecompliance

Significant contribution…Significant contribution…
• 19 percent of electricity19 percent of electricity
from hydropowerfrom hydropower
–– more than 50% in 63more than 50% in 63
countriescountries
• dams support 30-40% of irrigateddams support 30-40% of irrigated
areaarea && 12-16% of global food12-16% of global food
productionproduction
• 12% of all dams have a12% of all dams have a
water supply functionwater supply function
• 75 countries have dams for75 countries have dams for
flood controlflood control
Dams andDams and DDevelopmentevelopment -- RReport of theeport of the WWorldorld CCommisommisssion onion on DDamsams

• irrigationirrigation – almost half have under-performed– almost half have under-performed
……opportunities for efficiency gainsopportunities for efficiency gains
• hydropowerhydropower – on average met expectations but– on average met expectations but
considerable variabilityconsiderable variability
• flood controlflood control – dams have attenuated floods, but some– dams have attenuated floods, but some
increasedincreased vulnerabilityvulnerability
• physical sustainabilityphysical sustainability – safety– safety
improving,improving, but dams arebut dams are
aging and costs risingaging and costs rising
……loss of storage, 0loss of storage, 0.5.5 to 1.0%to 1.0%
per yearper year
Predicted vs actual generation
TWh
Kariba
Predicted
1960 2000
0
10
6
Considerable number have fallen below targets…Considerable number have fallen below targets…
Actual

Economic & financial under-performance…Economic & financial under-performance…
• average cost overruns ofaverage cost overruns of
over 50%over 50%
• 50% in survey with one50% in survey with one
year or more delayyear or more delay
• cost recovery incost recovery in
hydropower but nothydropower but not
irrigationirrigation
• poor economic andpoor economic and
financial results fromfinancial results from
irrigationirrigation
• mixed results formixed results for
hydropowerhydropower

Significant impacts on riverineSignificant impacts on riverine
& downstream ecosystems…& downstream ecosystems…
• lloss of riverineoss of riverine &&
terrestrial biodiversityterrestrial biodiversity
• adverseadverse impactsimpacts onon
livelihoods in floodplainslivelihoods in floodplains
• 67% of ecosystem changes67% of ecosystem changes
in survey are negativein survey are negative
• ppoor record of ecosystem mitigationoor record of ecosystem mitigation
• ssome reservoirs have created habitats forome reservoirs have created habitats for
biodiversitybiodiversity
• rreservoirs emit green-house gaseseservoirs emit green-house gases

Heavy toll on affected communities…Heavy toll on affected communities…
• estimated 40-80 million physically displacedestimated 40-80 million physically displaced
• significant number of othersignificant number of otherss affectedaffected
• failure to adequatelyfailure to adequately
recogniserecognise && respond torespond to
those affectedthose affected
• negative impacts fallnegative impacts fall
disproportionately ondisproportionately on
disadvantageddisadvantaged
• inequityinequity isis notnot addressedaddressed inin ‘balance sheet’‘balance sheet’
approachapproach

Alternatives often exist…Alternatives often exist…
• reduce demand by increasingreduce demand by increasing end-use efficiencyend-use efficiency
• defer new supply by enhancing supplydefer new supply by enhancing supply &&
conveyance efficiencyconveyance efficiency
• extend life and performance through improvedextend life and performance through improved
landland && waterwater managementmanagement
• promote alternative supply options, includingpromote alternative supply options, including
small-scalesmall-scale && locally appropriate approacheslocally appropriate approaches

Lack of compliance…Lack of compliance…
• wweak regulatory frameworkseak regulatory frameworks && lack of enforcementlack of enforcement
• llittle public participationittle public participation && scrutinyscrutiny
• ttop down decision-making, often politicallyop down decision-making, often politically
motivatedmotivated
• ppast conflicts remain unresolved with no legalast conflicts remain unresolved with no legal
recourserecourse
• vvested interests in favour of large infrastructureested interests in favour of large infrastructure
• nno incentives or sanctionso incentives or sanctions

What did the Commission find from theWhat did the Commission find from the
knowledge base ?knowledge base ?
Dams have delivered considerableDams have delivered considerable
benefitsbenefits
In too many cases the price paid toIn too many cases the price paid to
secure those benefitssecure those benefits hashas
been unacceptablebeen unacceptable
andand often unnecessaryoften unnecessary

Unprecedented response to the controversy …Unprecedented response to the controversy …
• WCD created through unanimous agreementWCD created through unanimous agreement
• broad based mandate to review development effectiveness &broad based mandate to review development effectiveness &
assess alternatives…assess alternatives…
…… and develop internationally acceptable criteriaand develop internationally acceptable criteria
and guidelinesand guidelines
• address global problems through local understandingaddress global problems through local understanding
• WCD’s authority and credibility rests on the diversity of theWCD’s authority and credibility rests on the diversity of the
Commissioners which was a guiding theme throughout its inclusive,Commissioners which was a guiding theme throughout its inclusive,
transparent and participatory work program.transparent and participatory work program.

Inclusive, Participatory & Transparent …Inclusive, Participatory & Transparent …
• full range of perspectives –full range of perspectives – civil society to governments,civil society to governments,
private sector to NGOs, financiers to foundationsprivate sector to NGOs, financiers to foundations
• outreach through work program and networksoutreach through work program and networks
• extensive review processextensive review process
• WCD Forum as a reference pointWCD Forum as a reference point
• draft studies on website www.dams.orgdraft studies on website www.dams.org

The Way ForwardThe Way Forward
• Move beyond the simpleMove beyond the simple
“balance –sheet approach”“balance –sheet approach”……
……to sto shared values, objectiveshared values, objectives andand goalsgoals
• InternationalInternationallyly accepted norms are basisaccepted norms are basis
for WCD recommendationsfor WCD recommendations
• Adopt a rightsAdopt a rights andand risks approachrisks approach
• Define whose rightsDefine whose rights andand what riskswhat risks

Move beyond the simple “balance-sheet”Move beyond the simple “balance-sheet”
approach that…approach that…
• trades off lossestrades off losses andand gains between groupsgains between groups
• impoverishesimpoverishes somesome peoplepeople
• excludes people and limitexcludes people and limitss awarenessawareness
• overlooks sustainability aspectsoverlooks sustainability aspects
• induces conflictinduces conflict andand higher costshigher costs

Towards shared values, objectives & goals…Towards shared values, objectives & goals…
• equityequity
• efficiencyefficiency
• participatory decision-makingparticipatory decision-making
• sustainabilitysustainability
• AccountabilityAccountability

Define whose rights & what risks…Define whose rights & what risks…
RRisksisks
• Move beyond considering voluntary risk takersMove beyond considering voluntary risk takers
to include involuntary risk bearersto include involuntary risk bearers
RightsRights
• No party’s rights should extinguish another’sNo party’s rights should extinguish another’s
• Where rights compete – negotiated agreementsWhere rights compete – negotiated agreements
are neededare needed

Turning Conflict Into ConsensusTurning Conflict Into Consensus
• Gain public acceptanceGain public acceptance
• Assess optionsAssess options
• Address existing damsAddress existing dams
• Sustain rivers and livelihoodsSustain rivers and livelihoods
• Recognize entitlements and share benefitsRecognize entitlements and share benefits
• Ensure complianceEnsure compliance
• Share rivers across boundariesShare rivers across boundaries
Seven Strategic prioritiesSeven Strategic priorities

Gaining public acceptanceGaining public acceptance……
• dams affect existing rightsdams affect existing rights && createcreate wide range of riskswide range of risks
• opportunities exist for achieving a highopportunities exist for achieving a higherer levellevel ofof
equityequity
• recognise rights of indigenousrecognise rights of indigenous && tribal peoplestribal peoples
• achieve outcomes through binding formal agreementsachieve outcomes through binding formal agreements

• failure to adequately definefailure to adequately define
needsneeds && assess options led toassess options led to
disputedispute
• an early and open examinationan early and open examination
of optionsof options can avoid poorcan avoid poor
projectsprojects
• raise the significance of socialraise the significance of social
&& environmental aspectsenvironmental aspects
• increase the effectiveness ofincrease the effectiveness of
existingexisting systems as a prioritysystems as a priority
Comprehensive optionsComprehensive options
assessmentassessment……

Address existing damsAddress existing dams……
• most dams that will operate in themost dams that will operate in the
2121stst
century already existcentury already exist
• considerable scope exists forconsiderable scope exists for
improving benefitsimproving benefits
• remedy outstanding social issuesremedy outstanding social issues
……enhance mitigation, restorationenhance mitigation, restoration &&
enhancement of ecosystemsenhancement of ecosystems
• use licenuse licensses to formalizees to formalize
operating agreementsoperating agreements

Sustain rivers and livelihoodsSustain rivers and livelihoods……
• rivers supportrivers support millions ofmillions of livelihoodslivelihoods
• dams cause significant and oftendams cause significant and often
irreversible effects on ecosystemsirreversible effects on ecosystems
• valuevalue rivers,rivers, ecosystemsecosystems & endangered& endangered
speciesspecies
• emphasise avoidanceemphasise avoidance
of impactsof impacts
• maintain ecosystemmaintain ecosystem
integrity throughintegrity through
environmental flowsenvironmental flows

Recognize entitlementsRecognize entitlements && share benefitsshare benefits ……
• manymany peoplepeople displaced - manydisplaced - many
moremore ununrecognisedrecognised
• includingincluding thosethose whowho depend on adepend on a
river’s resourcesriver’s resources
• recognise rights and assess risksrecognise rights and assess risks
as a basis for negotiationsas a basis for negotiations
• agree legally enforceableagree legally enforceable
entitlementsentitlements
• adverselyadversely affected peopleaffected people becomebecome
first among beneficiariesfirst among beneficiaries

Ensure complianceEnsure compliance ……
• many policies and guidelines exist..many policies and guidelines exist..
• but often a failure to fulfill obligationsbut often a failure to fulfill obligations
• need a compliance plan covering all commitmentsneed a compliance plan covering all commitments toto
people and the environmentpeople and the environment
• introduce initiatives to reduce corruptionintroduce initiatives to reduce corruption
• develop incentive framework for compliancedevelop incentive framework for compliance

Share rivers across boundariesShare rivers across boundaries……
• conflicts over transboundary rivers dueconflicts over transboundary rivers due toto
power imbalancepower imbalance
• experience suggests disputes can be resolvedexperience suggests disputes can be resolved
• endorse the UN Convention principlesendorse the UN Convention principles
• go beyond sharing water - to sharing the benefitsgo beyond sharing water - to sharing the benefits
• encourageencourage consistent policies for financingconsistent policies for financing
agenciesagencies

Dams in the pipeline - it’s not too lateDams in the pipeline - it’s not too late
FeasibilityFeasibility - assess all optionsassess all options
- gain public acceptancegain public acceptance
DesignDesign - prepare Compliance Plan- prepare Compliance Plan
- contractualize benefit sharing- contractualize benefit sharing
- determine environmental flow- determine environmental flow
ConstructionConstruction -- fformalize commitmentsormalize commitments

BY :- SAGAR MANDALBY :- SAGAR MANDAL
X-AX-A

sagar725744

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