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DAMS AND RESERVOIRS

DAMS AND RESERVOIRS. Digley Reservoir, Holmbridge. 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.

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DAMS AND RESERVOIRS

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  1. 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. 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. Digley Dam, Holmbridge Stone armour to protect dam from erosion by waves 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.

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

  14. 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 damsGravity 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. Buttress dams are similar to gravity dams, but the buttresses at the front of the dam take the weight of the water. Buttress dams 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? An embankment dam What type of dam is this? Butterley Dam, Marsden

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

  24. 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

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