4.6 Multipurpose dam projects

Question 1

factors affecting the choice of site of a dam-

7 points

Answer 1

• Rivers and lakes nearby to provide water
• The valley should be quite narrow, where the dam is built (wider dam would be more costly)
• A dam also needs to be quite high up a valley (Higher it is,the greater the pressure of water,will have more potential energy)
• Should be sited away from the developed areas to reduce the risk of getting pollution in the reservoir.
• High precipitation to provide sufficient water;
• Low temperature to prevent evaporation;
• Built on strong impermeable rock so water doesn’t drain and has a good foundation;

Question 2

advantages of a dam

9 points

Answer 2

• Generation of electricity in hydro-electric power plants;
• Flood control;
• Irrigation
• Creates recreational land for tourism and leisure
• Provision of water
• Creation of habitat for wetland species
• Renewable source of energy so Doesn’t produce greenhouse gases
• Reduces fossil fuel consumption
• Creates more jobs

Question 3

disadvantages of a dam

7 points

Answer 3

• Relocating people
• Flooding land
• Disrupting the lifecycles of fish and other aquatic organisms.
• Altering the water supply for people downstream of the dam.
• Reducing the enrichment of soil downstream of the dam.
• Dam may become redundant due to sediment build up
• expensive to build

Question 4

Sustainability of dams:

Answer 4

Alternative for burning of fossil fuels as no greenhouse gases are produced.

Question 5

Unsustainability of dams:

Answer 5

• Reservoir can become silted due to material carried into it by rivers;
• Dam structure under a lot of pressure can deteriorate and eventually fail;
• Have negative effects on the environment and fish population.