Grande Dixence Dam Switzerland Flashcards
Facts:
Highest gravity dam in the world.
In a glaciated landscape
Constructed in 1960
Had alterations in 2010
The dam itself:
285 metres tall, 200m wide
Stores 400 million m3 of water each year
Generates enough power annually for 1.2 million Swiss households
The environmental impact - positive
The environmental impact of the project has been minimised, partly to ensure the area was still attractive to visitors.
Pumping stations and power plants are largely built underground or are concealed to retain aesthetics. This has been proven effective, as there are now tours around the area.
The environmental impact - negative
However, the reduced flow in the Borgne River, a tributary of the Rhone, below the dam has resulted in higher concentrations of pollutants at les haudere, from both agricultural / domestic sources.
Impact on the glacial system:
15% of the water used to solve problems from sedimentation.
Sedimentation is the deposition load behind the dam which is caused as there is a loss of energy in the flow of water.
Sediment buildup is around 20-40 cm a year.
In order to solve this problem water is purged in order to move the sediment downstream.
Impact on river channels:
The trapping of sediment behind the dam leads to very clear water being returned to the natural river channels.
When excess water is discharged, there is increased water energy as the stream isn’t carrying sediment - This causes increased channel erosion.
In summer however there is a lack of discharge, causing streams to dry up.
Sediment content in Lake Geneva has halved since dam was constructed.
In Val d’Herens, however, there is a risk of flooding when excess stored water has to be released.
Impact on Humans:
The flooding in Val d’Herens has hindered tourist use and development on the valley floor, although local residents receive significant revenues from the dam due to visitors, so are overall in favour of the scheme.
