River Exe

Question 1

Location?

Answer 1

Starts on Exmoor in Somerset and flows south for 60 miles, reaching the sea on the south coast of Devon.

Question 2

Area?

Answer 2

600 km^2

Question 3

Max elevation?

Answer 3

515m in the north

Question 4

Min elevation?

Answer 4

26m in the south

Question 5

Geology?

Answer 5

84.4% impermeable rocks such as Devonian sandstone

Question 6

Composition of land use?

Answer 6

67% agricultural grasslands, 15% woodland, 3% peat bogs and 15% other (mainly arable farmland)

Question 7

Water balance equation?

Answer 7

Precipitation(1295mm) = Evaporation +/- Soil water storage(451mm) + Runoff(844mm)

Question 8

Why is runoff unusually high?

Answer 8

High rainfall is normally absorbed by the peaty moorlands, however, the drainage ditches and impermeable geology has resulted in high runoff.

Question 9

What is the Wimbleball Reservoir?

Answer 9

Its a reservoir with an area of 150 hectares that was created when the river Haddeo was dammed in 1979.

Question 10

What does the Wimbleball Reservoir do?

Answer 10

It supplies water to Exeter and parts of East Devon, whilst regulating water flow all year.

Question 11

How does the Wimbleball Reservoir prevent flooding and droughts?

Answer 11

It regulates water flow and levels within the reservoir which helps minimise peaks and troughs in hydrographs, reducing the risk of floods and droughts.

Question 12

What are drainage ditches and why have they been built?

Answer 12

They are deep trenches carved into the hillside to drain the water that has been absorbed by the peat bogs, allowing the land to be used for farming.

It has also been dug to be used as a biofuel and to heat homes.

Question 13

What are the negative impacts of drainage ditches on the water cycle?

Answer 13

Increased speed of water flow into the river Exe, increasing likelihood of flooding and soil erosion, resulting in more silt in the river which lowers water quality.

Question 14

What are the negative impacts of drainage ditches on the carbon cycle?

Answer 14

As peat bogs dry out due to lack of moisture, decomposition occurs releasing carbon in the form of CO2 and Methane.

Question 15

How does the Exmoor Mires project work?

Answer 15

By blocking drainage ditches with peat blocks or moorland bales, water is retained in the peat and the ground returns to its natural moorland environment.

This helps to reduce the flow of water into river channels and allows the peat to store more carbon.

Question 16

Area aimed to be restored?

Answer 16

2,000 hectares.

Question 17

Current progress of the Exmoor Mires project?

Answer 17

By 2015 over 1,000 hectares of moorland had been restored and nearly 100km of drainage ditches have been blocked.

Question 18

Benefits of the Exmoor Mires project already seen?

Answer 18

The water table has risen by 2.65cm and reduced the amount of water that drains from this area by 2/3.

Question 19

Benefits of the Exmoor Mires project on the water cycle?

Answer 19

Water transfer is slowed, increasing the storage capacity and the steady supply of water, in the upper catchment.

Slower surface runoff and throughflow reduces silt in rivers, improving water quality and protecting wildlife.

Question 20

Benefits of the Exmoor Mires project on the carbon cycle?

Answer 20

Peat is an important carbon store but dry peat releases carbon, so increasing water content in the soil allows for active peat growth and carbon to be absorbed from the atmosphere.

Question 21

General benefits of the Exmoor Mires project?

Answer 21

Improved grazing and water supply for animals all year round.

Improved opportunities for education because peatland habitats are very biodiverse.