1. Digley Reservoir, Holmbridge
DAMS AND RESERVOIRS
Digley Reservoir, Holmbridge

2. 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.

3. Draw a diagram to show the perfect site for a dam and reservoir.
Area of high rainfall
Impermeable rocks underlying reservoir
No faults or major joints
Dip of rocks
reservoir
dam
Quarry to provide rock in large amounts
Strong rock foundations for dam supports

4. There are four main types of dams:
Embankment dams
Arch dams
Gravity dams
Buttress dams

5. Embankment dams Butterley dam and reservoir, Marsden
This dam has a by-pass channel to prevent overtopping of the dam by water.

6. Diagram of an embankment dam.
Explain each feature of this dam.
Diagram from Geology and Environment in Britain and Ireland by Nigel Woodcock

7. Draw a diagram of an embankment dam.
Add a title
water
Rock or earth fill
core
Rock or earth fill
Cut-off

8. Plan and cross section of Digley Dam, 1947, Holmbridge
overflow
Plan and cross section of Digley Dam, 1947, Holmbridge
reservoir
road
Stony earth fill to add weight
water
Impermeable clay

9. Earth embankment at Digley, Holmbridge
reservoir
Road on top of dam
Earth fill

10. Stone armour to protect dam from erosion by waves
Digley Dam, Holmbridge
High water level
Stone armour to protect dam from erosion by waves
Rip rap is a layer of large rocks which cannot be moved by waves. Rip rap protects the earth dam from erosion.

11. Overflow on Digley Dam
This maintains the reservoir level at its maximum height and prevents it overflowing.

12. 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.

13. Hoover Dam, R. Colorado, U.S.A
Arch dams
Strong rock abutments in a narrow valley
Hoover Dam, R. Colorado, U.S.A

14. Explain each feature of this dam.
Diagram of an arch dam
Explain each feature of this dam.
The dam will be very firmly anchored to the walls at each side of the valley.

15. Draw a diagram of an arch dam.
Dam will need firm anchorages at both sides.
reservoir
Curved shape to brace against weight of water.
Add a title

16. Gravity dams Gravity dams are kept in place by virtue of their weight with braces them against the weight of water behind.
Three Gorges Dam, China

17. Diagram of a gravity dam

18. Draw a diagram of a gravity dam.
Weight to keep dam stable
Reservoir
Made of strong rock or concrete
Wide base for stability
Add a title

19. Glen Errochty, Scotland.
Buttress dams
Buttress dams are similar to gravity dams, but the buttresses at the front of the dam take the weight of the water.
Glen Errochty, Scotland.

20. Diagram of a buttress dam.

21. Draw a diagram of a buttress dam.
Strong rock sides
Buttress braces dam against the weight of the water
reservoir
Internal fill of impermeable material
Add a title

22. What type of dam is this? What type of dam is this? An embankment dam
Butterley Dam, Marsden

23. What type of dam is this? A buttress dam
Chief Joseph Dam, Washington State, USA

24. Grand Coulee Dam, Washington State, USA
What type of dam is this?
A gravity dam
Grand Coulee Dam, Washington State, USA

25. What type of dam is this? Arch Dam
Kariba Dam, River Zambezi, between Zimbabwe and Zambia

26. What type of dam is this? Buttress/gravity dam
Hume Dam, River Murray, Australia

27. THE END