presentation(hydropower dam)

8/9/2019 Presentation(Hydropower Dam)

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daDROPOW


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What isdam?


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A dam is a man-made structure builtacross a river. Mostly to control river fow,improve navigation, regulate fooding.However, some dams are built to producehydroelectric power.


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How do dams makehydroelectric power?


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Hydroelectric power is produced as waterpasses through a dam, and into a river

below. he more water that passes througha dam, the more energy is produced. !ncea dam is built, an arti"cial man-made lakeis created behind the dam.

#lectricity is produced by a device called aturbine. urbines contain metal coils

surrounded by magnets. When themagnets spin over the metal coilselectricity is produced. urbines arelocated inside dams. he $alling waterspins the magnets.

%ams provide clean, pollution $ree energy,

but they can also harm the environment.&pecies that use rivers to spawn are o$tenhut by dams.


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ypes o$ Hydropower%ams

here are two basic types o$ hydropowerplants ' those that impound water behinda dam and those that divert water into achannel parallel to the river (o$ten called)run-o$-river) hydropower plants*


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+our (* phases stageso$ dam proect/


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+easibility report stage

%etailed pro ect

report stage

ender preparation stage

0onstruction stagedesign


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+ailure to plan the site layout in advance isa prime cause o$ operational ine1ciency,

and can increase the overall cost o$ apro ect substantially. 2n the absence o$ aprecise site layout plan, the $ollowingproblems may occur/

he 3roblem


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A. Material stacks wrongly located. Materialsarriving on site are o4-loaded into what

someone guesses to be the correct location. his problem may involve double or triplehandling o$ materials to another location. +ore5ample/

hey may stocked over a drainage line ornear the edge o$ e5cavation6

hey are too $ar $rom the work area6 hey are too remote $rom the hoist or notwithin the radius o$ the crane6

hey impede the smooth fow o$ worktra1c across the site6

heir delivery was wrongly phased andthey are not needed until much later in the

pro ect6

hey are $ragile.


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7. 3lant and e8uipment wrongly located. +ore5ample/

he mi5er is inaccessible $or the delivery o$materials6 not enough room $or the storageo$ aggregates6

+i5ed cranes are unable to reach all partso$ the works6

Hoists have insu1cient capacity or heightto handle the loads or badly located inrelation to the foor layout6


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0. 2nade8uate space allowed. Whereinade8uate space is allowed $or the stacking o$

materials or activities/

Materials may be stacked to high orstacked on roadways causing ha9ards.

Working areas may become too crampedor additional areas may have o beallocated with the conse8uent waste o$

time caused by having to travel betweenthem.


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How to build a dam?


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&tep : o build a %am the engineers must "rst de-water the part o$the river valley in which they wish to place the dam. his isusually achieved by diverting the river through a tunnel.

he tunnel is built through one side o$ the valley around theplanned construction area. A series o$ holes is drilled in therock. #5plosives are placed in the drill holes, blasting takesplace and broken rock is then removed. his procedure isrepeated many times until the tunnel is completed.

%iversion tunnels are o$ten lined with concrete.


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&tep ;Work on diverting the river starts in summer when riverlevels are low. #arth-moving e8uipment is used to build asmall dam (called a co4erdam* upstream o$ the mainconstruction area. his acts as a barrier to the river andcauses it to fow through the diversion tunnel.

Another co4erdam is built downstream o$ the main damsiteto prevent water fowing back into the construction area.3umps are used to remove any water that seeps throughthe co4erdams.

%iversion tunnels are not always necessary when concretedams are being built. he river can sometimes bechannelled through a large pipe and the dam constructedaround it.


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&tep < he construction methods used in building a dam depend

on the type o$ dam being built. he "rst stage normallyinvolves the removal o$ loose rock and rubble $rom thevalley walls and river bed.

0oncrete-$aced rock"ll dams re8uire a $ooting (or plinth* to

be constructed around their upstream edge. he plinth ismade $rom concrete and serves as a $oundation orconnection between the dam and the valley walls and foor.2t has an important role in preventing water leakage aroundthe edges o$ the dam. he area under the plinth iswaterproo$ed by drilling holes and pumping cement groutinto cracks in the rock. he thin concrete $ace on theupstream side o$ the dam is connected to the plinth viastainless steel and rubber seals called waterstops.


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#=hank you $orlistening

presentation(hydropower dam)

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