DAMSSheela Malik

AP CivilGITAM Kablana

Dams

• Dam is a solid barrier constructed at a suitablelocation across a river valley to store flowing water.

Storage of water is utilized for following objectives:

• Hydropower• Hydropower

• Irrigation

• Water for domestic consumption

• Drought and flood control

• For navigational facilities

• Other additional utilization is to develop fisheries

Structure of Dam

Spillway(inside dam)

Crest

NWLNormalwater level

MWLMax. level

Upstream Down stream

Heel

Gallery

Toe

Free boardSluice way

• Heel: contact with the ground on the upstream side

• Toe: contact on the downstream side

• Abutment: Sides of the valley on which the structure of the dam rest

• Galleries: small rooms like structure left within the dam for checkingoperations.

• Diversion tunnel: Tunnels are constructed for diverting water before theconstruction of dam. This helps in keeping the river bed dry.

• Spillways: It is the arrangement near the top to release the excess waterof the reservoir to downstream side

• Sluice way: An opening in the dam near the ground level, which is usedto clear the silt accumulation in the reservoir side.

TYPES OF DAMS

• Gravity Dams:• These dams are heavy

and massive wall-likestructures of concretein which the wholeweight acts vertically

ReservoirForce

weight acts verticallydownwards

As the entire load is transmitted on the small area of foundation, such dams are constructed where rocks are competent and stable.

• Bhakra Dam is the highestConcrete Gravity dam inAsia and Second Highestin the world.

• Bhakra Dam is across riverSutlej in Himachal Pradesh

• The construction of thisproject was started in theyear 1948 and wasyear 1948 and wascompleted in 1963 .

• It is 740 ft. high above the deepest foundation as straight concrete dam being more than threetimes the height of Qutab Minar.

• Length at top 518.16 m (1700 feet); Width at base 190.5 m (625 feet), and at the top is 9.14 m (30feet)

• Bhakra Dam is the highest Concrete Gravity dam in Asia and Second Highest in the world.

Buttress Dam:

• Buttress Dam – Is agravity dam reinforced bystructural supports

• Buttress - a support thattransmits a force from aroof or wall to anotherroof or wall to anothersupporting structure

This type of structure can be considered even if the foundationrocks are little weaker

• These type of dams areconcrete or masonry damswhich are curved or convexupstream in plan

• This shape helps to transmitthe major part of the water load

Arch Dams:

the major part of the water loadto the abutments

• Arch dams are built acrossnarrow, deep river gorges, butnow in recent years they havebeen considered even for littlewider valleys.

Plan of Idukki Arch Dam

Earth Dams:

• They are trapezoidal inshape

• Earth dams areconstructed where thefoundation or theunderlying material orrocks are weak to supportthe masonry dam or wherethe masonry dam or wherethe suitable competentrocks are at greater depth.

• Earthen dams arerelatively smaller in heightand broad at the base

• They are mainly built withclay, sand and gravel,hence they are also knownas Earth fill dam or Rockfill dam

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