Switzerland case study

Question 1

what is the dam called?

Answer 1

Grande Dixence scheme

Question 2

Where is the dam located?

Answer 2

Valdes dix in south west switzerland

Question 3

Features of the dam

Answer 3

• highest gravity dam globally
• stored 400 mil m3 of water anually
• catchment of 350km2 - 1/2 of is glacial meltwater
• has enough energy to power 400,000 households

Question 4

Positive impacts on environment

Answer 4

• pumping stations underground (aesthetic)
• Tourism and locality has been enhanced - helicopter rides above the dam

Question 5

Negative impacts on the environment

Answer 5

• reduced flow into borgne river resulting in higher polutants from agriculutral and domestic sources

Question 6

impacts on the glacial system

Answer 6

Water available 85% used for electricity
* water stored behind the dam - the lack of flow means a loss of energy and deposition behing the dam
* sediment concentrations are 20-50 mg/l below the dam

Question 7

What was done to solve the issue of less deposition behind the dam?

Answer 7

• some of the water within. the reservoir is used to purge at the sediment pushing it downstream

Question 8

Impacts on river channels

Answer 8

• trapping of sediment leads to clearwater being returned to the water below powerstations
• excess energy being used to transport sediment - increases channel erosion
• changes to size of contraction channel with it increasing downstream ( amount of sediment in Lake geneva has 1/2)
• Risk of sudden flood in val herens

*hinders tourist use although residents still receive significant revenue *

Question 9

environmental positives of the dam

Answer 9

• Less than 5% of electricity production comes from fossil fuels
• Impact reduced as pumping stations built underground meaning that habitats are well concealed and undisturbed
• Trapping of sediment means that clear water is returning into the
  natural river therefore there is no pollution Minimised to ensure that the area remains an attractive site for walkers, cyclists and hikers
• Pumping stations and power plants largely built underground
• Tourism was increased through guided tours and helicopter rides to see the dam

Question 10

Economic positives

Answer 10

• The opportunity for more business as tourists are spending money in the area causing a positive multiplier effect.
• Putting money back in to the economy by obtaining aggregates locally
• Hydroelectric power is cheaper as is fuelled from natural energy source. Saving the government money so that they can put more in to schools, hospitals and roads.
• 95% of the power is now created from HEP

Question 11

economic negatives

Answer 11

• Initial cost for construction - 1600 million Swiss Francs

Question 12

Social negatives

Answer 12

• Often construction entails the resettlement of local people
• Not everyone is happy with the dam as it is anaesthetically pleasing.
• Some people aren’t happy with the increase in people in and around their settlements
  (tourists)

Question 13

Environmental negatives

Answer 13

• Climate change causes glaciers to melt meaning new lakes are being formed
• Rock slides increase as temperature rises because the permafrost holding the surfaces together is
  melting. This could provoke tsunami like waves. The dams need to be high enough to prevent the
  water spilling over.
• In the last 20 years there is an increasing amount of sediment getting in to reservoirs as a result of
  erosion. This threatens to block outflow and other abrasive nature seriously damages the turbines -
  constantly rubbed by sandpaper.
• Reduced flow in the Borgne River, a tributary of the Rhône below resulted in higher concentration
  of pollutants at Les Haudère. These are from agricultural and domestic resources.