glaciated landscape grande dixence scheme

Question 1

background

Answer 1

• situated at the head pf the Val des dix in southwest Switzerland
• highest gravity dam in the world
• provide Switzerland whey hydroelectric power
• hard to construct on it due to condition and inaccessibility which means could only be improved in summer months in 2010, too cold in winter for conecrete to set

Question 2

the dam

Answer 2

• 285 meters high
• each year stores 400 million m3 of water
• has a catchment area of 350km2 half of which is from 35 glaciers that provide seasonal meltwater
• the lac des dix was created behind the dam and four pumping stations send water through 100km off tunnels into the resovior.

Question 3

energy

Answer 3

• water stored behind the dam drives the turbines in 4 power stations which creates enough power to do 400,000 Swiss homes
• about 1/3 of Swiss power comes from storage power stations

Question 4

impact of enviornment

Answer 4

• impact has been minimised, so it remains an attractive area for walkers, cyclist and hikers. the pumping stations and power plants are mainly underground
• however the reduced flow of one river gas resulted in higher concentration of pollutants from both agricultural and domestic socuress

Question 5

impact on glacial system

Answer 5

• of the water available 85% is used mainly for electricity generation, over 15 is used to deal with the problems of sedimentation.
• when water is stored behind the dam the lack of flow means a loss in energy and deposition of sediment load behind the dam at rates of 20-40cm/year
• to solve this problem some of the water in the reservoir is used to purge the sediment flushing it away and downstream

Question 6

impact on river channels

Answer 6

• the trapping of the sediment behind the dam leads to very clear water being returned into the natural river channels below the power stations.
• the lack of discharge in the below dam rivers means that some of virtually dry up in the summer.
• in the Val d’heroes however there is a sudden risk and unexpected flooding when excess stored of water has to be released.

Question 7

other landscape impacts

Answer 7

• in 2000 a high pressure pipeline from the dam burst causing a landslide and killing 3 people