Case study of how a river is affected by processes in the water cycle

Question 1

Where is the River Exe?

Answer 1

Source in exmoor, mouth is exmouth

Question 2

What is the maximum elevation of the river exe?

Answer 2

514m

Question 3

What is the lowest elevation of the river exe?

Answer 3

26m

Question 4

How much of the river is underlain by impermeable rocks?

Answer 4

84.4%

Question 5

What type of land use dominates the area of the river exe?

Answer 5

Grassland

Question 6

How much does grassland account for in the river exe?

Answer 6

67%

Question 7

What is the water balance equation?

Answer 7

P = O + E +/- soil water storage

Question 8

How much does runoff account for in the river exe’s water balance?

Answer 8

65%

Question 9

Why does the river exe have such a high runoff rate?

Answer 9

Impermeable nature of bedrock reduces percolation

Drainage ditches on Exmoor reduce the amount of soil water storage

Question 10

The water cycle and water balance have been significantly affected by two recent developments, which ones?

Answer 10

Construction of Wimbleball Reservoir

Restoration of peatland on Exmoor

Question 11

What river was dammed to create Wimbleball Reservoir?

Answer 11

River Haddeo

Question 12

What does the reservoir do?

Answer 12

Supply water to Exeter and parts of East Devon
Regulates water flow ensuring a steady flow regime
Prevents the peas and troughs of water discharge that make flooding or drought more likely

Question 13

Why have drainage ditches been dog in the peat bogs of Exmoor?

Answer 13

To make it suitable for farming

Question 14

What is the problem with the drainage ditches?

Answer 14

Increased the speed of water flow to the Exe, which reduces water quality as more slit is carried downstream
Ugly scars have been left
Peat has dried out - decomposition has occurred releasing carbon

Question 15

What project has worked to restore the peat bogs?

Answer 15

The Exmoor Mires project

Question 16

How have The Exmoor Mires project worked to restore the peat bogs?

Answer 16

Blocked drainage ditches with peat blocks or moorland bales

Question 17

Why have the Exmoor Mires project blocked drainage ditches with peat blocks or moorland bales?

Answer 17

To increase water content and return the ground to the saturated boggy conditions

Question 18

Why is it important the drainage ditches return to boggy conditions?

Answer 18

Help retain carbon stored within the peat

Question 19

How many hectares does TEMP aim to restore?

Answer 19

2000

Question 20

What will the benefits be to restoring 2000ha of Exmoor to boggy conditions?

Answer 20

More water storage in upper catchments 
Improved water quality 
More carbon storage 
Improved opportunities 
Improved grazing and water supply for animals

Question 21

Why is water storage in upper catchments a benefit of TEMP?

Answer 21

Water transfer is slowed, increasing storage capacity and ensuring a steady supply of water throughout the year

Question 22

Why is improved water quality a benefit of TEMP?

Answer 22

Slower through flow means that less sediment is carried into rivers. Water is cleaner less expensive to treat and good for wildlife

Question 23

Why is more carbon storage a benefit of TEMP?

Answer 23

Peat is essentially carbon and water, and therefore an important carbon store. Dry peat, however releases carbon dioxide through oxidation. By encouraging the re-wetting of peat and active peat growth, CO2 is naturally absorbed from the atmosphere and stored

Question 24

Why is improved opportunities a benefit of TEMP?

Answer 24

It will advocate opportunities for education, leisure and recreation. Peatland habitats are very biodiverse, with many species of plants, birds, butterflies and insects

Question 25

Why is improved grading and water supply for animals a benefit of TEMP?

Answer 25

Animals benefit form having year round drinking water, as well as improved grazing during the drier parts of the year

Question 26

By 2010, how much peat moorland was restored?

Answer 26

1000ha

Question 27

How many ditches have been blocked?

Answer 27

100km

Question 28

By how much has the blocking of 100km of ditches raised the water table by?

Answer 28

2.65cm

Question 29

How was the changes in the water table measured?

Answer 29

Using dip wells

Question 30

How do dip wells work?

Answer 30

They are inserted into the ground and when they make contact with water, a buzzer or light is activated and a depth measurements can be taken