Lecture 9 - The Environmental and Social Impacts of Large Scale Dams

  1. Dam Uses - Direct Water Usage?
    • 1) Private/domestic
    • 2) Irrigation
    • 3) Commercial
    • 4) Livestock
    • 5) General publics supply
    • 6) Industrial
    • 7) Mining
  2. Dam Uses - Indirect Uses?
    • 1) Hydroelectric Power (clean)
    • 2) Flood control (calm seasonal flooding, and then store that water for gradual release year round)
    • 3) Transportation (on rivers that were traditionally wild)
  3. Global distribution of water resources varies greatly because of ___.
    Climate, topgraphy, geology, hydrology, upstream water usage, historic water usage.
  4. Name the three types of dams.
    Gravity, Arch, Buttress.
  5. Characteristic (name dam): triangular shape.
    Gravity Dam.
  6. Characteristic (name dam): Weight of the rock and concrete structure hold back water in the reservoir.
    Gravity Dam.
  7. Characteristic (name dam): Most common type of large dam.
    Gravity Dam.
  8. Characteristic (name dam): Cheap to build.
    Gravity Dam.
  9. Characteristic (name dam): Example: Aswan Dam, Egypt.
    Gravity Dam.
  10. Characteristic (name dam): Can be build across large distances over relatively flat terrain.
    Gravity Dam.
  11. Characteristic (name dam): Applicable in non-mountainous regions.
    Gravity Dam.
  12. Characteristic (name dam): use strength of an arch to displace the load of water behind it onto the rock walls that it is built into.
  13. Characteristic (name dam): ex) Hoover Dam.
  14. Characteristic (name dam): Walls of canyon must be of unquestionable stability.
  15. Characteristic (name dam): Must be impervious to seepage around dam, as this may be a source of dam failure in the future.
  16. Characteristic (name dam): Can only be build in limited locations.
  17. Characteristic (name dam): Use less materials than gravity dams.
  18. Characteristic (name dam): More expensive to construct.
  19. Characteristic (name dam): Use multiple reinforced columns to support a dam.
  20. Characteristic (name dam): Relatively thin structure.
  21. Characteristic (name dam): Often use 1/2 as much concrete as gravity dams.
  22. A combination of one or more dam types, often a large part will be either an embankment/gravity dam, and the section responsible for power generation will be a buttress or arch dam.
    Composite dams.
  23. Materials used for dam creation.
    Soil, sand, stone, aggregate, concrete - fossil fuels are required to operate machinery, creating air/water pollution.
  24. Primary ingredient in dams.
  25. Concrete is a mixture of these two components: ___.
    Aggregate and paste (portland cement and water - this binds together the fine and coarse aggregates).
  26. Typical mix of concrete (%).
    • 10-15% cement.
    • 10-20% water.
    • 60-75% sand/aggregate.
    • 5-8% air.
  27. Physical impacts (upstream): A stagnant water table can ___.
    Destroy flora. Also, water from unnatural reservoirs seeps into the water table.
  28. Physical impacts (upstream) include ___.
    Stagnant water table, loss of land, habitat destruction.
  29. Physical impacts (on-site): changes in water characteristics include:
    • - Temperature (greater SA exposed to sun, aquatic life cannot adjust).
    • - Salinity
    • - Sediment Load (sediments wash down the river and settle into large reservoirs).
    • - Nutrient Content (causing eutrophication).
    • - O2 Content.
  30. On-site impacts: construction causes ___.
    Dust, noise pollution.
  31. On-site impacts: water pollutants include ___.
    • - industrial and residential pollutants
    • - agricultural runoff (including high nitrate loads, fertilizers and pesticides).
    • - boats, jet skis.
  32. On-site impacts: Habitat destruction is caused by:
    roads, transmission lines, increased migration.
  33. On-site impacts: What is exotic species introduction?
    Aggress,ve non-native species of fish aer often introduced to reservoirs for farming and sport fishing.
  34. On-site impacts: mosquito-breeding is encouraged in tropical areas, which encourages the transmission of ___.
    Malaria, dengue and schistosomiasis (snail fever).
  35. On-site impacts: What is reservoir-induced seismicity? What is its proposed mechanism?
    • The weight of unnatural reservoirs can cause seismic activity.
    • Proposed mechanism: when the pressure of the water in the rocks increases, it lubricates faults which are already under tectonic strain, but have been prevented from slipping by the friction of the rock surfaces.
  36. Downstream impacts: flow reduction causes ___.
    Habitat destruction, water table reduction.
  37. Downstream impacts: changing natural flood patterns: natural floods inunate downstream regions with ___.
    Nutrient-rich sediments.
  38. Downstream impacts: Traditional farming systems in countries like ___.
    Egypt (the Nile) and Bangladesh (the Ganges).
  39. Displacement (India/China): About ___ have been displaced over the last 50 years due to China's dam building.
    12.2 million.
  40. Displacement (India/China): About ___ will be displaced by the Three Gorges project.
    1.1 to 1.3 million.
  41. Displacement: The Three Goges project will cost about ___.
    $24.65 billion.
  42. Social Impacts: Which rivers still have ongoing conflict?
    The Nile, The Ganges, the River Jordan, the Colorado, the Parana.
  43. Financial Impacts: The greatest single source of funds for large dam construction:
    The World Bank.
  44. Finacial impacts: Amount given to countries for dam construction by the World Bank.
    $50 billion (1992 dollars) for construction.
  45. Financial impacts: The number of dams the World Bank has helped build.
    500 large dams in 92 countries.
Card Set
Lecture 9 - The Environmental and Social Impacts of Large Scale Dams
Lecture 9 - The Environmental and Social Impacts of Large Scale Dams