water and carbon cycles CS 2( river catchment/ drainage basin- river Exe) Flashcards Preview

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Flashcards in water and carbon cycles CS 2( river catchment/ drainage basin- river Exe) Deck (21)
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1
Q

where is the river Exe?

A

source Hills in Exmoor, through Tiverton and Exeter to sea at Exmmouth

2
Q

how long is the River Exe?

A

82.7km

3
Q

name 3 physical characteristics of the River Exe?

A
  • area if upper catchment 601 km
  • max elevation 514m in N
  • lowest elevation 26m in S
4
Q

what are the 2 geology characteristics of the river?

A
  • 84.4% of catchment is underlain by permeable rocks

- predominantly Devonion sand stones extensive drainage works

5
Q

what are the 4 land use characteristics?

A
  • 67% argi land
  • 15% woodland
  • 3%of exmoor/peatbogs
  • arable farmland
6
Q

what is the water balance equation for the river?

A

precipitaion (1295mm)= evaporation+/- soil water storage (451mm) + surface run off (844mm)

7
Q

what is the water balance over exmoor?

A

increased rainfall

8
Q

what happens to the rainfall over exmoor?

A

much absorbed by peaty soils

9
Q

what is the cause for water to flow of hills rapidly over exmoor?

A

drainage ditches or saturated land

10
Q

what are the 2 reasons for ‘runoff accounts for 65% of WB increase?’

A

1) imperbale nature of bedrock= reduced percolation and base flow
2) drainage ditches on exmoor reduce amount of soil water storage

11
Q

what were the two developments?

A
  • construction of wimbleball res

- restoration od peatland on exmoor

12
Q

how was the reservoir created?

A

1979 river haddeo (upland trip of river exe) was dammed to create WR

13
Q

what is the surface area of the res?

A

150 her

14
Q

what are the two main aims of the res?

A
  • supplies water to Exeter and parts of east Devon

- regulates flow, ensure steady flow of regime during year (prevents peaks and troughs that make flooding more likely)

15
Q

why was there a peatland restoration scheme?

A

drainage ditches dug in peat bogs so suitable for farming= ^ speed of water flow to exe= reduces water quality & more silt carried down stream

16
Q

how did they restore the land?

A

blocked drainage ditches with peat blocks/ Moreland bales

17
Q

how do the peat bogs remain back to natural state?

A

^ water content & returns the ground to saturated, boggy conditions that would naturally occur in this moorland

18
Q

what do these saturated conditions help?

A

retain carbon stored within the peat

19
Q

what is the Exmoor mires project (EMP)?

A

aim to restore 2000ha of exmoor to boggy conditions

20
Q

what are the top 4 benefits of the EMP?

A
  • more water storage in upper catchments (steady supply of water)
  • improved water quality (slowed through flow mega sless sediment carried into rivers= clean water)
  • more carbon storage (peat=water+C)
  • improved grazing and water for animals
21
Q

what were the 3 achievements in 2015?

A
  • 1000ha restored
  • 10km of ditches blocked
  • raising water table by 2.65 cm