coasts Flashcards

1
Q

sediment cells

A

Coasts can be split into sections called sediment cells which are often bordered by prominent headlands.

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2
Q

how many sediment cells are in the uk?

A

11

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3
Q

coastal inputs

A

marine:
-waves
Atmosphere:
-wind
humans:
-pollution

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4
Q

coastal outputs

A

-currents
-riptides
-evaporation

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5
Q

coastal transfers

A

-longshore drift
-erosion

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6
Q

hydraulic action

A

water crashing against the coastline causing material to be dislodged and carried away by the sea.

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7
Q

corrosion

A

a process of chemical erosion.

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8
Q

attrition

A

rocks hit against each other

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9
Q

abrasion

A

rocks carried by the sea are picked up by strong waves and thrown against the coastline.

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10
Q

coastal stores

A

-beaches
-dunes
-spits

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11
Q

rivers as a sediment source

A

-account for majority of sediment

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12
Q

sediment sources

A

-rivers
-cliff erosion
-wind

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13
Q

sediment budget

A

the balance of inputs and outputs in the coastal system

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14
Q

littoral zone

A

area of land between the cliff’s or dunes on the coast and the
sea.

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15
Q

short term factors impacting the littoral zone

A

-tides
-storm surges

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16
Q

long term factors impacting the littoral zone

A

-changes in sea level
-human intervention

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17
Q

wave formation

A

• Wind blows across the sea surface.
• Energy from the wind is transferred to the water.
• The water moves in a circular motion.
• as the water gets more shallow waves grow in height

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18
Q

factors effecting wave energy

A

-strength of wind
-duration of wind

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19
Q

constructive wave characteristics

A

-long wavelength
-6-9 per min
-strong swash, weak backwash

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20
Q

destructive wave characteristics

A

-short wavelength
-25 per min
-weak swash, strong backwash

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21
Q

spring tide

A

-highest high tide, lowest low tide
-occur when the sun and the moon are in
alignment, so their gravitational forces work with each other

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22
Q

neap tide

A

-lowest high tide and the highest low tides -when the sun and the moon are
perpendicular to each other, so their gravitational forces work against each other

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23
Q

rip currents

A

powerful underwater currents occurring in areas close to the shoreline on some
beaches

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24
Q

wave refraction

A

waves bend as they hit the coastline at an angle, causing uneven distribution of energy and influence coastal shaping through erosion and deposition.

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25
Q

wave quarrying

A

This is when breaking waves hit the cliff face to directly pull away rocks from a cliff face

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26
Q

factors effecting erosion

A

-Waves
-Beach Size and Presence
- Rock type

27
Q

longshore drift

A

-Waves hit the beach at an angle determined by the direction of the prevailing wind
-The waves push sediment up the beach in the swash
-The wave then carries sediment back down the beach in the backwash
-This moves sediment along the beach over time

28
Q

mechanical weathering

A

freeze thaw:
-Water enters cracks in rocks and then the water freezes and expands in volume causing cracks to develop
Salt Crystallisation:
-As seawater evaporates, salt is left behind. Salt crystals will grow over time, forcing the cracks to widen.

29
Q

chemical weathering

A

carbonation:
-rainwater is slightly acidic
Oxidation:
-When minerals become exposed to the air they become oxidised which
increases volume causing the rock to crack.

30
Q

biological weathering

A

Plant Roots:
- Roots of plants growing into the cracks of rocks, which exerts pressure,
eventually split the rocks
Birds:
-Some birds such as Puffins dig burrows into cliffs weakening them

31
Q

soil creep

A

The movement of soil particles downhill.

32
Q

mass movement

A

movement of material down a slope under the influence of gravity

33
Q

mudflow

A

An increase in the water content of soil can reduce friction, leading to earth and mud to
flow over underlying bedrock.

34
Q

landslide

A

when a
block of intact rock moves down the cliff face very quickly

35
Q

slump

A

Contrary to a landslide, the slope is curved, the land collapses under its
own weigh

36
Q

Wave-cut Notch

A

-Erosion is concentrated around the high-tide line creating a wave-cut notch
- As the notch becomes deeper the cliff face becomes unstable and collapses
- This leaves behind a platform of the unaffected cliff base

37
Q

swash aligned beach

A

Waves break parallele to the coast

38
Q

drift aligned beach

A

Waves approach at angle, so sediment travels along the beach, which may form
a spit.

39
Q

spit

A

-Occur when the coast suddenly changes direction
-Longshore drift continues to deposit material in line with the coast but at sea
-Changes in wind direction lead to a curved end ( spit)
-Area behind the spit is mudflats and saltmarshes

40
Q

barrier beach/ bar

A

-Occurs when a beach or spit extends across a bay to join to headlands
-Traps water forming a lagoon which is separated from the sea

41
Q

tombolo

A

-Bar that connects the mainland to an offshore island

42
Q

offshore bar

A

-An offshore region where sand is deposited , as the waves don’t have enough energy to carry the sediment to shore. They absorb wave energy

43
Q

sand dunes

A

-Wind blows sand landwards from beach
-Dunes develop as a process of a vegetation succession: roots hold sand together

44
Q

Isostatic sea level change

A
  • when the land rises or falls relative to the sea
    -localised change
    -EG. tectonic activity
45
Q

Eustatic sea level change

A

-affects sea level across the whole planet.
-may be due to thermal expansion/contraction

46
Q

Contemporary Sea Level Change

A

-Since 1880 sea levels have
increased by around 23cm

47
Q

hard engineering examples

A

-groynes
-sea wall
-rock armour
-revetments

48
Q

groynes

A

Timber protrusions that
trap sediment from LSD

49
Q

groynes pros and cons

A
  • build up the beach
  • cost effective
    x visually unappealing
    x increases erosion down shore
50
Q

sea wall pros and cons

A
  • highly effective
    -tourism benefits
    x expensive to construct and maintain
    x visually unappealing
51
Q

rock armour

A

Large rocks that reduce wave
energy

52
Q

rock armour pros and cons

A
  • cheap
    x don’t fit natural geology
    x can be a safety hazard
53
Q

revetments

A

Wooden or concrete ramps that
help absorb wave energy

54
Q

revetments pros and cons

A

-cheap
x visually unappealing
x need constant maintenance

55
Q

soft engineering examples

A

-beach nourishment
-dune stabilisation
-managed retreat

56
Q

beach nourishment

A

Sediment is taken from offshore
sources to build up the existing beach

57
Q

beach nourishment pros and cons

A

-cost effective
-looks natural
x needs constant maintenance
x dredging may have consequences on habitats

58
Q

dune stabilisation

A

Marram grass planted. The roots
help bind the dunes, protecting land behind

59
Q

dune stabilisation pros and cons

A
  • cost effective
  • creates a habitat
    x planning is time consuming
60
Q

managed retreat

A

Type of managed retreat
allowing low-lying areas to flood

61
Q

Integrated Coastal Zone Management

A
  • environmental protection is prioritised over economic development
  • must involve all stakeholders
  • In 2013 the EU adopted a new initiative which promotes the use of ICZM’s
61
Q

managed retreat pros and cons

A
  • creates a habitat
    x farmers have to be given compensation
62
Q

Shoreline Management Plans (SMPs)

A

-There is an SMP for each UK sediment cell.
-Different factors are considered when choosing a management options: The economic value of
assets that could be protected, the technical feasibility and the
ecological and cultural value of land