dams and reservoirs digley reservoir, holmbridge
TRANSCRIPT
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DAMS AND RESERVOIRS
Digley Reservoir, Holmbridge
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Factors which affect the location of dams
• Areas of high rainfall so the dam is filled naturally.• Sources of local stone, earth or concrete so that transport
costs are not too high.• A high local water table so that water does not leak away.• Based on impermeable rocks so that water does not leak
out.• Concrete or rock dams need firm foundations so that they
can be safely anchored.• Rocks should dip upstream not downstream so that the
dam does not slide down the valley.• An area which is not earthquake prone, otherwise the
dam could be damaged.• There should be no faults or major joints so that water
does not leak out.• Local rocks do not contain heavy mineral veins, like lead
or zinc which would pollute the water.
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Draw a diagram to show the perfect site for a dam and
reservoir.
Quarry to provide rock in large amounts
Area of high rainfall
Dip of rocks
Strong rock foundations for dam supports
reservoir
No faults or major joints
Impermeable rocks underlying reservoir
dam
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There are four main types of dams:
•Embankment dams•Arch dams•Gravity dams•Buttress dams
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Embankment dams
This dam has a by-pass channel to prevent overtopping of the dam by water.
Butterley dam and reservoir, Marsden
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Diagram of an embankment dam.
Diagram from Geology and Environment in Britain and Ireland by Nigel Woodcock
Explain each feature of this dam.
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Draw a diagram of an embankment dam.
coreRock or earth fill
Rock or earth fill
Cut-off
water
Add a title
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Plan and cross
section of Digley Dam,
1947, Holmbridge
road
water
reservoir
overflow
Impermeable clay
Stony earth fill to add weight
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Earth embankment at Digley, Holmbridge
Earth fill
Road on top of dam
reservoir
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High water level
Rip rap is a layer of large rocks which cannot be moved by waves. Rip rap protects the earth dam from erosion.
Stone armour to protect dam from erosion by waves
Digley Dam, Holmbridge
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Overflow on Digley Dam
This maintains the reservoir level at its maximum height and prevents it overflowing.
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Back of Winscar Dam, Dunford Bridge.
This dam started to leak in 2000 and was emptied so that it could be repaired.
It was covered by an impermeable membrane to prevent water leaking through cracks in the concrete.
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Hoover Dam, R. Colorado,
U.S.A
Strong rock abutments in a narrow valley
Arch dams
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Diagram of an arch damExplain each feature of this dam.
The dam will be very firmly anchored to the walls at each side of the valley.
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Draw a diagram of an arch dam.
Dam will need firm anchorages at both sides.
Curved shape to brace against weight of water.
reservoir
Add a title
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Gravity damsGravity dams are kept in place by virtue of their weight with braces them against the weight of
water behind.
Three Gorges Dam, China
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Diagram of a gravity dam
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Draw a diagram of a gravity dam.
Reservoir
Weight to keep dam stable
Wide base for stability
Made of strong rock or concrete
Add a title
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Buttress damsButtress dams are similar to gravity dams, but the buttresses at the front of the dam take the weight of the water.
Glen Errochty, Scotland.
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Diagram of a buttress dam.
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Draw a diagram of a buttress dam.
reservoir
Internal fill of impermeable material
Strong rock sides
Buttress braces dam against the weight of the water
Add a title
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What type of dam is this?
Butterley Dam, Marsden
What type of dam is this?
An embankment dam
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What type of dam is this?A buttress dam
Chief Joseph Dam, Washington State, USA
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What type of dam is this?A gravity dam
Grand Coulee Dam, Washington State, USA
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What type of dam is this?
Kariba Dam, River Zambezi, between Zimbabwe and Zambia
Arch Dam
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What type of dam is this?Buttress/gravity dam
Hume Dam, River Murray, Australia
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