River Exe

Question 1

Where is the river?

Answer 1

Exmoor hills National Park to Exmouth, Devon

Question 2

Physical Environment?

Answer 2

Steep-surface runoff- 600km2 upper catchment
84% impermeable rock (devonian sandstone)
increased throughflow when water hits bedrock

Question 3

Land use?

Answer 3

67% agricultural grassland- interception and longer lag time
15% woodland- Roots reduce soil erosion
3% peat bog

Question 4

Local water cycle

Answer 4

coastal to the atlantic-heavy rain all year: majority absorb by peat bogs, saturation and drainage ditches=overland flow
slow response to rainfall events- short lag time, slow flood recovery time
high runoff- 65% of water balance, steep, grassland=limited interception, impermeable rock, drainage ditches reduce soil water storage

Question 5

2 ways in which the catchment is affected by development?

Answer 5

Wimbleball reservoir, Peatland restoration on exmoor

Question 6

Wimbleball reservoir

Answer 6

1979- River Haddeo dammed, supplies water to Exeter and east Devon
Regulates waterflow, releases into exe-prevent flooding, no groundwater supplies

Question 7

Success?

Answer 7

Water table up by 2.65cm
reduced drainage by 2/3rds
Sequester more carbon
increase quality & supply of water, increase biodiversity

Question 8

Peatland restoration on exmoor

Answer 8

Drainage ditches used to be dug in peat to make it suitable for farming: reduce lag time, decline in water quality as sediment carried into river
peat dug for fuel and compost- when drier it releases CO2

Question 9

What is the exmoor mires project?

Answer 9

problem: mires may dry out as ditches dug and peat cutting, moors water capacity reduced- oxidation of exposed peat bogs- lots of carbon released
Solution: restore 2000ha of bogs
block ditches with bales of peat & increase water storage capacity

Question 10

Impact project has had?

Answer 10

peat cutting- reduces storm surges, less floods-1/3 less water in storms
water filters through vegetated peat
rewetted peat bogs slows down water run-off from land before steadily releasing it.
flood less likely- lower soil erosion and silt entering rivers

Question 11

middle course characteristics

Answer 11

lots of vegetation (large areas of forest)

• rural - not many buildings - caravan park, farmland, castle
• not as steep as upper course, average approx. 250m

Question 12

Lower course characteristics

Answer 12

high density buildings

• barely any vegetation (only golf course)
• low lying land - approx. 40m

Question 13

Upper course characteristics

Answer 13

land use - town, hotel, housing (concrete)

• little vegetation (few areas of forest)
• steep sloping land around the river - average 350m

Question 14

what areas are at the most risk from flooding?

Answer 14

Exeter and Exmouth - 2,000 to 5,000 properties at risk

Question 15

what areas are at the least risk from flooding?

Answer 15

Cowley and Bampton - 100 to 250 properties at risk