River Exe Case Study Flashcards
Where is the River Exe?
Devon, in between Dartmoor and Exmoor.
What are some features of the River Exe’s drainage basin?
- Long shaped.
- Steep sided valleys in middle courses.
- High drainage density.
- Lots of tributaries.
Does it have a flashy or subdued river regime?
Flashy.
What is the maximum altitude of the drainage basin?
516m
What percentage of rocks are considered to be highly permeable?
2.5%
What percentage of the drainage basin is:
Woodland?
Grassland?
Woodland: 13%
Grassland: 57%
What percentage of total land use is farmland?
80.5%
How many properties are at risk of flooding?
11,000
Which areas of the river are most at risk of flooding?
Exeter and Tiverton because they are main urban areas with lots of impermeable surfaces.
Why are there lots of drainage ditches in the drainage basin?
Farmers encouraged to dig them to increase food production after WW2.
What is the name of the key reservoir on the river?
Wimbleball Reservoir.
How much water is held in the Wimbleball Reservoir and why is this important?
120 million litres. Reduces flood risk to Exeter and Tiverton.
What is the main type of farming?
Pastoral farming (cattle, sheep).
Who is involved in the Exmoor Mires project?
- South West Water.
- Environment Agency.
- Exeter University.
What does “Slowing the Flow” do for the river?
Water is backed up behind the mud, reduces carried sediment. 20% cheaper to treat water and reduces flashy hydrographs on the river.
How much has the Exmoor Mires project cost?
£2.2 million.
How does raising the height of the water table help with the carbon cycle on Exmoor?
Peat cannot react with oxygen, meaning more carbon is stored in the peatlands (carbon sink).
What is the name of the moss near the river and how much water can it hold?
Spagnem - can hold 20x its weight in water.
How much more water do the Exmoor Mires hold after the Exmoor Mires project?
33% more - water table rose by 2.2cm across the moorland.
