Site Selection for Dams & Reservoirs (Original)

7/24/2019 Site Selection for Dams & Reservoirs (Original)

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Site Selection forDams and Reservoirs

Dr. P. Sarathbabu

ANU


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Dam

Barrier that stores water at two levels.

The primary purpose of dam is to store

water whenever available in plenty foruse durin scarcity.

Built across rivers

!"cess water is released to river anduseful water is transferred thro canals


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Dams are constructed for water storae forcommunity and industrial use# irriation# flood

control# hydro electric power# river canali$ation.

Dams depends on environmental conditionsparticularly the eoloy of the site.

Safety is the first consideration and than cost as that

the failure of a dam results in sevior loss of life andproperty.


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%omponents of Dam

Body of Dam &oundation

Top road

'ates and liftin devices

Spill way or Sluice

%anal

Reservoir

(ain river course

Stillin Basin

Drainae allery


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%omponents ) &orces in Dams

Reservoir

*ater

&oundation Soil

Dam Body

&oundation

Upstream Down Stream

Drainae 'allery

Spill *ay

'ate

Sluice ateStillin Basin


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Upstream

Down Stream

Reservoir

*ater


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Abutment

Abutment

Main River Course

Riht ban+ %anal

Reservoir

,eft Ban+ %anal

Upstream

Downstream

Plan of Dam


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Reservoir

*ater


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Preliminary -nvestiations for Dam site

This investiations are made to ascertain itsimportant merits or demerits. This +ind ofinvestiation is necessary# so that detailedinvestiations which are much more e"pensive#e"tensive and laborious should be made only if the

site is approved. The important informationcollected at this stae is as follows.

. ,itholoy

/. Structure0. Physioraphy 1Toporaphy2

3. 'round *ater %onditions


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Site selection criteria for the dams and reservoirs

Basin on the analysis of dam problems# failures and ha$ards

it may be concluded that the dam sites to satisfy the followinre4uirements.

. The roc+ should be sound and resistant to the e"pectedstatic and dynamic forces includin earth4ua+es.

/. The valley slope should be stable when the reservoir isfull. This re4uirement also applies to the roc+abutments.

0. The foundation of the dam should be safe from slidin#

especially in the case of ravity dam.

3. The roc+ used for the foundation should be of oneeoloic classification to avoid variations in the values

of modulus of elasticity.


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5. The foundation and the reservoir wall should be watertiht.

6. The roc+ at the site should be resistant to solution#

erosion# decomposition and other detriment effects ofwettin and dryin free$in and thawin.

7. The reservoir drainae area includin roc+s andoverburden should be resistant to erosion and therefore

not li+ely to contribute such heavy silt loads to thereservoir.

8. The eoloy and toporaphic conditions should permitfavourably for the location of spillways and diversiontunnel# power house and outlet conduits.

9. The location of construction materials particularlyconcrete areate should be with in an economically

:ustified distances.


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Function Example

Powergeneration

Hydroelectric poweris a major source of electricity in the world. manycountries have rivers with adequate water flow, that can be dammed for powergeneration purposes. For eg, the taipuon the Paran! "iverin #outh $mericagenerates %& '(and supplied )*+ of the energy consumed by Paraguayand-+ of that consumed by ra/ilas of --0.

#tabili/e waterflow 1 irrigation

2ams are often used to control and stabili/e water flow, for agriculturalpurposes and irrigation. 3hey can help to stabili/e or restore the water levelsof inland la4es and seas. 3hey store water for drin4ing and other direct humanneeds,

Flood prevention 2ams are created for flood control.

5andreclamation

2ams 6often called dy4es or levees7 are used to prevent ingress of water to anarea that would otherwise be submerged, allowing its reclamation for humanuse.

(ater diversion 2ams are used for the purpose of diversion.

&UN%T-;NS ;& DA(S
http://en.wikipedia.org/wiki/Hydroelectric_powerhttp://en.wikipedia.org/wiki/Itaipuhttp://en.wikipedia.org/wiki/Paran%C3%A1_Riverhttp://en.wikipedia.org/wiki/South_Americahttp://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Paraguayhttp://en.wikipedia.org/wiki/Brazilhttp://en.wikipedia.org/wiki/Agriculturehttp://en.wikipedia.org/wiki/Irrigationhttp://en.wikipedia.org/wiki/Irrigationhttp://en.wikipedia.org/wiki/Agriculturehttp://en.wikipedia.org/wiki/Brazilhttp://en.wikipedia.org/wiki/Paraguayhttp://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/South_Americahttp://en.wikipedia.org/wiki/Paran%C3%A1_Riverhttp://en.wikipedia.org/wiki/Itaipuhttp://en.wikipedia.org/wiki/Hydroelectric_power


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%,ASS-&-%AT-;N 1T


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. ST;RA'! DA( ;R -(P;UND-N' DA(

-t is constructed to create a reservoir to storewater durin periods when there is hue flow

in the river 1in e"cess of demand2 for

utilisation later durin periods of low flow

1demand e"ceeds flow in the river2.

*ater stored in the reservoir is used for

irriation# power eneration# water supplyetc. By suitable operation# it can also serve

as a detention dam.


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/. D!T!NT-;N DA(

-t is primarily constructed to temporarily

detain all or part of the flood water in a river

and to radually release the stored water

later at controlled rates so that the entirereion on the downstream side of the dam is

protected from possible damae due to

floods.

-t may also be used as a storae dam.


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0. D-=!RS-;N DA(

-t is constructed to divert part of or all

the water from a river into a conduit or

a channel.

&or divertin water from a river into an

irriation canal# mostly a diversion weiris constructed across the river.


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3. %;&&!R DA(

-t is a temporary dam constructed toe"clude water from a specific area. -t is

constructed on the u>s side of the site

where a dam is to be constructed sothat the site is dry.

-n this case# it behaves li+e a diversion

dam.


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5. D!BR-S DA(

It is constructed to catch and retain debris flowing in a

river


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BAS!D ;N ?


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. ;=!R&,;* DA( ;R ;=!R&A,, DA(

-t is constructed with a crest to permit overflow

of surplus water that cannot be retained in the

reservoir.

'enerally dams are not desined as overflow

dams for its entire lenth.

Diversion weirs of small heiht may be

desined to permit overflow over its entire

lenth.


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/. N;N@;=!R&,;* DA(

-t is constructed such that water is not

allowed to overflow over its crest.

-n most cases# dams are so desined that part

of its lenth is desined as an overflow dam1this part is called the spillway2 while the rest

of its lenth is desined as a non@overflow

dam.

-n some cases# these two sections are not

combined.


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BAS!D ;N (AT!R-A, ;&

%;NSTRU%T-;N

. R-'-D DA( /. N;N@R-'-D DA( 1!(BAN(!NT DA(S2

. R-'-D DA(

-t is constructed with riid material such as stone#

masonry# concrete# steel# or timber.

Steel dams 1steel plates supported on inclinedstruts2 and timber dams 1wooden plan+s supported

on a wooden framewor+2 are constructed only for

small heihts 1rarely2.


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/. N;N@R-'-D DA( 1!(BAN(!NT DA(S2

-t is constructed with non@riid material such as earth#

tailins# roc+fill etc.

!arthen dam ravel# sand# silt# clay etc

Tailins dam waste or refuse obtained from mines

Roc+fill dam roc+ material supportin a water tiht

material on the u>s face

Roc+fill composite dam Roc+fill on the d>s side and

earth fill on the u>s side


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!arthen dams are provided with a stone

masonry or concrete overflow 1spillway2

section. Such dams are called compositedams.

-n some cases# part of the lenth of the damis constructed as earth dam and the rest

1e"cludin the spillway2 as a masonry dam.

Such dams are called masonry cum earthen

dams.


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BAS!D ;N STRU%TURA, B!?A=-;UR

'RA=-T< DA(

AR%? DA( BUTTR!SS DA(

!(BAN(!NT DA(


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'RA=-T< DA(

-t is a masonry or concrete dam which

resists the forces actin on it by itsown weiht. -ts c>s is appro"imately

trianular in shape.

Straiht ravity dam A ravity dam

that is straiht in plan.

%urved ravity plan A ravity dam

that is curved in plan.


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%urved ravity dam 1Arch ravity dam2

-t resists the forces actin on it by

combined ravity action 1its own weiht2and arch action.

Solid ravity dam -ts body consists of a

solid mass of masonry or concrete ?ollow ravity dam -t has hollow

spaces within its body.

(ost ravity dams are straiht solidravity dams.


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%oncrete 'ravity Dams

*eiht holds dam in place

,ots of concrete 1e"pensive2

These dams are heavy and massive

wall@li+e structures of concrete in

which the whole weiht acts vertically

downwards


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As the entire load is transmitted on the small

area of foundation# such dams are constructed

where roc+s are competent and stable.

Bha+ra Dam is the highest Concrete Gravity dam in Asia

and the second highest in the world.

Bha+ra Damis across river utle! in "imachal #radesh

$he construction of this pro!ect was started in the year

%&'( and was completed in %&)* .

It is +', ft. high above the deepest foundation as straight

concrete dam being more than three times the height of

-utab Minar.


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,enth at top 58.6m 17CC feet2 width at

base 9C.5m 16/5 feet2# and at the top is

9.3m 10C feet2

Bha+ra Dam is the hihest %oncrete 'ravity

dam in Asia and Second ?ihest in the world.


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/. AR%? DA(

-t is a curved masonry or concrete dam# conve"

upstream# which resists the forces actin on it by

arch action.

The only arch dam in -ndia -du++i dam 1double

curvature in plan2 concrete arch dam

Arch Dams

Arch shape ives strenth

,ess material 1cheaper2 Narrow sites

Need stron abutments


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These type of dams are concrete or masonrydams which are curved or conve" upstream inplan

This shape helps to transmit the ma:or part ofthe water load to the abutments

Arch dams are built across narrow# deep riverores# but now in recent years they havebeen considered even for little wider valleys.


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0 BUTTR!SS DA(


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0. BUTTR!SS DA(

-t consists of water retainin slopin membrane or dec+on the u>s which is supported by a series of buttresses.These buttresses are in the form of e4ually spacedtrianular masonry or reinforced concrete walls orcounterforts.

The slopin membrane is usually a reinforced concreteslab. -n some cases# the u>s slab is replaced by multiplearches supported on buttresses 1multiple arch buttressdam2 or by flarin the u>s ede of the buttresses to span

the distance between the buttresses 1bul+head buttressdam or massive head buttress dam2. -n eneral# thestructural behaviour of a buttress dam is similar to thatof a ravity dam.


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Buttress Dam -s a ravity damreinforced by structural supports

Buttress a support that transmits aforce from a roof or wall to another

supportin structure

This type of structure can be

considered even if the foundationroc+s are little wea+er.


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Buttress Dams

ace is held up by a series of supports

lat or curved face


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. !(BAN(!NT DA(

-t is a non@riid dam which resists the forces actinon it by its shear strenth and to some e"tent alsoby its own weiht 1ravity2.

-ts structural behaviour is in many ways different

from that of a ravity dam.

!arth or roc+

*eiht resists flow of water


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!arth Dams

They are trape$oidal in shape.

!arth dams are constructed where the foundation orthe underlyin material or roc+s are wea+ to supportthe masonry dam or where the suitable competent

roc+s are at reater depth.

!arthen dams are relatively smaller in heiht andbroad at the base.

They are mainly built with clay# sand and ravel#hence they are also +nown as !arth fill dam or Roc+fill dam


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Classification of /ams

Based on Si$e

Based on function

Based on material used


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%lassification based on Si$e

Small Dam 1EC m hih2

(edium si$e Dam 1C /5 m hih2

,are Dam 1F/5 m hih2 (a:or Dam 1F5C m hih2


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Classification based on #urpose

?ydro@electric dam

-rriation dam

*ater supply dam for city for the purposes of drin+in

water# recreation# naviation thro canals# industrial use.

&lood %ontrol

?abitat dam for fishes ) wild life

!ffluent containin dams from industry# mine# factory

etc.

(ulti@purpose dam


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Classification based on Material of construction

(asonry Dam

%oncrete Dam

Timber Dam

Steel Dam

!arth Dam

Roc+fill Dam %omposite Dam


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%lassification based on action

'ravity Dam

Arch Dam

Saddle Dam

%hec+ Dam

Diversion Dam

;verflow Dam

%offerdam


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'ravity Dam Timber Dam

Steel DamSan ,uis Dam near ,os Bonos#

%alifornia an !mban+ment

Dam


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Spillway

?oover Arch Dam

Power eneration Plant

%offerdam


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Steel Dam

Timber Dam


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Arch Dam

Solid 'ravity Dam

Roc+fill Dam


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%ombined !arth ) Roc+fill Dam

!arth Dam

DA( S-T!S ;& S;(! -ND-AN DA(S


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DA( S-T!S ;& S;(! -ND-AN DA(S

Bha+rananal DamG It is situtated in the gorge of

utle! River where roc0s consist of alternating bands of lightred clays and fairly hard1 thic0 bedded sandstones with a

steep down stream dip1 varying between +,C2(,C with the

hori3ontal.

?ira+ud DamG $he dam is situated across theMahanadi river. $he foundation of roc0s consists of Granitewith schistose bands1 Granitic gneisses1 shales and

4uart3ites.

Beas DamG $he foundation roc0s at the 5eas dam siteconsists alternate layers of sandstones and shales of siwali0


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Naar:unasaar DamG $he roc0 types e6posedin and around the dam site are the granite gneisses of

the peninsular gneissic comple6 and the 4uart3ites andshales belonging srisailam stage of cuddapah system.

Srisailam DamG $he main roc0 types are 4uart3iteboulders1 sand intermi6ed with clay.


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Real 7ife

Give an e6ample or real life anecdote

ympathi3e with the audience8s situation if appropriate

Site Selection for Dams & Reservoirs (Original)

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