River processes and pressures Flashcards

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1
Q

What are the main features of a drainage basin ?

A

WATERSHED : highland that seperates drainage basins
CONFLUENCE : where two rivers meet
TIBUTARY : smaller stream that joins bigger stream
SOURCE : starting point of a stream
MOUTH : where stream joins sea

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2
Q

How are interlocking spurs created ?

A
  • source of rivers have less power so flow around hard rock

- makes them bend around rock and for interlocking spurs

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3
Q

What are the features of meanders ?

A
  • river gains more energy at middle course
  • as river flows over flatter land, meander forms
  • speed and erosion increases on outside of bend
  • deposition on inside
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4
Q

How are ox-bow lakes formed ?

A
  • meanders get closer due to erosion
  • makes neck of lake narrower
  • high discharge = river will take shortest route and erode neck
  • makes straighter course
  • gradual deposition cuts of meander
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5
Q

How are levees formed ?

A
  • occur in lower course
  • when river flood it loses energy
  • largest materials deposited first
  • smaller materials further away
  • sediment build up to form levee
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6
Q

What are the features of a flood plain ?

A
  • land that gets covered when river flood
  • interlocking spurs are removed
  • overtime height increases due to increased deposition
  • often agriculture land
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7
Q

What are deltas and how are they formed ?

A
  • found at mouth

- forms from sediment deposited by river as it enters slower moving water

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8
Q

How does the profile of a river change ?

A

U : steep, narrow shallow channel, steep sides

M : medium, wider deeper channel, gently sloping sides

L : gentle, very wide deep channel, very wide (almost flat) valley

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9
Q

Why is the flood risk in the UK rising ?

A
  • increased population = more housing on flood plains
  • urban development = more impermeable surfaces = increased surface run off
  • change in weather patterns = more storms (from every 100yrs to 80yrs)
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10
Q

How does the EA manage flood risks ?

A
  • invested £2.8bn
  • manages river and land use
  • building flood defences
  • gives warning / helps people prepare
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11
Q

How is flooding reduced through CMP’s ?

A
  • reduce run off by improving land use
  • improve flood defences
  • prevent insuitable development on flood plains
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12
Q

What are the advantages to hard engineering ?

A

EMBANKMENTS : stop overflowing, blend with environment

FLOOD WALLS : prevent water spreading in high impacts areas

DEMOUNTABLE FLOOD BARRIERS : put up and taken down, replace ugly permanent defences

STORM SURGE BARRIERS : protect large areas

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13
Q

What are the disadvantages of hard engineering ?

A

EMBANKMENTS : can burst under high pressure

FLOOD WALLS : expensive, cause flooding downstream, look unnatural

DFB : risk of timing issues

STORM SURGE BARRIERS : high construction costs, regular maintenance

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14
Q

What are the advantages of soft engineering ?

A

RIVER RESTORATION : more attractive, creates habitats

FLOOD PLAIN RETENTION : low risk areas used for building, high risk used for parks

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15
Q

What are the disadvantages of soft engineering ?

A

RIVER RESTORATION : some flood bank often still needed

FLOOD PLAIN RETENTION : poor public accessibility in some areas

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