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Geography Case studies > Coastal Zones > Flashcards

Coastal Zones Flashcards

1
Q

Sea Level rise case study: East Anglia

What are the causes of Sea Level rise?

A

Main cause: thermal expansion of seawater- absorbs heat from the atmosphere

Melting glaciers/ ice (from land and sea) will increase the amount of water in the oceans
(but not significantly)

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2
Q

Sea rise case study: East Anglia

What are the social effects of Sea rise in East Angia?

A
  • Loss of homes due to increased erosion 🌊🏡
  • Properties devalued as a result
  • Loss of jobs- coastal industries shut down due to tourism decrease, damage to work buildings or equipment…
  • Migration from the area
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3
Q

Sea rise case study: East Anglia

Géneral effects.

A

Past 15 years: sea levels have risen on average by 3mm per year (varies from place to place)

The Intergovernmental Panel on Climate Change (IPCC) predicts a rise in global sea levels of between 28 and 43cm by the end of the century. —> dependent on levels of global warming.

In UK, most under threat= South East and East.
—> land is flat and at very low altitudes.

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4
Q

Sea rise case study: East Anglia

Social effects.

A

Loss of homes

Properties devalued

Loss of jobs:
-coastal industries shut down due to tourism decrease, damage to buildings etc.

Migration from the area

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5
Q

Sea rise case study: East Anglia

Economic effects.

A

The Thames Barrier will need replacement…

  • currently protects buildings worth £80 billion
  • will need replacement in the next 30-50 years
  • large areas of the lower Thames estuary will be at risk from flooding–> affects housing, industry and farmland.

Flooding of the Norfolk Broads:

  • popular tourist destination
  • currently bring £5m to the area
  • destroys the economy of the area!!
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6
Q

Sea rise case study: East Anglia

Political effects.

A

Managed retreat will in some places breach sea walls to allow deliberate flooding so that salt marshes can reform—> controversial political decision.

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7
Q

Sea rise case study: East Anglia

Environmental effects.

A

Many areas are at risk of FLOODING!
-Lower Thames estuary
-The Norfolk Broads
1m sea level change will change will flood London.

Possible storm surges
-East Anglia: in 1953, 300 people were killed by astir surge.

Agricultural land is flooded, eg in THE FENS, Norfolk

Loss of habitats:(

Areas of salt marsh are being squeezed between sea walls and rising sea
-22% of East Anglia’s salt marsh could be lost by 2050.

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8
Q

Cliff collapse case study: Barton-on-sea

What is Barton on sea?

A

A small settlement affected by Coastal erosion and cliff collapse.

Christchurch Bay is 16km long.
Parts are exposed to waves, with a fetch of 3000km for the Atlantic.

The area is densely populated with a number of towns situation along it. Tourism is important.

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9
Q

Cliff collapse case study: Barton-on-sea

Why are cliffs collapsing?

A

Marine processes, Sub-aerial processes, Geology, Human activity.

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10
Q

Cliff collapse case study: Barton-on-sea

Explain cliff collapse due to Marine processes.

A

The base of the cliffs are being attacked by the waves (hydraulic action and abrasion).

The large fetch results in powerful, destructive waves.

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11
Q

Cliff collapse case study: Barton-on-sea

Explain cliff collapse due to Sub-aerial processes.

A

Weathering is weakening the Rock, they are easily eroded and have little strength to resist collapse.
Slumping and Rock fall is leading to collapse.

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12
Q

Cliff collapse case study: Barton-on-sea

How does the geology of the area worsen cliff collapse?

A

The rocks are arranged as permeable sands on top of impermeable clay.

This causes water to ‘pond up’ within the cliffs when it rains, so the weight of the cliff increases.

The increase in water pressure within the cliffs encourages cliffs to collapse.

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13
Q

Cliff collapse case study: Barton-on-sea

How does human activity worsen cliff collapse?

A

Extensive building along the cliff top has resulted in too much weight on the soft cliffs, making them more vulnerable to collapse.

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14
Q

Cliff collapse case study: Barton-on-sea

How do the winds increase cliff collapse?

A

The Barton-on-sea stretch of coastline faces the direct force of the prevailing south- westerly winds.

The waves have a long fetch as a result so they cause great erosion.

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15
Q

Cliff collapse case study: Barton-on-sea

How do streams increase cliff collapse?

A

Small streams flow towards the coast, disappearing into the permeable sands before reaching the sea.

This increases water levels in the cliffs… increasing weight…

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16
Q

Cliff collapse case study: Barton-on-sea

What are the impacts of cliff collapse on Barton-on-sea?

A

loss of homes - house values decrease, house insurance very expensive, dangerous to walk on the cliff tops

roads under threat - dangerous, tourists may not visit, impacts local business, economic position of the sea worsens

cliff collapse looks unattractive - exposes different rocks and fossils… can also be a BENEFIT- interesting for those interested in fossils, scientists etc… eg Cliffs at Naish Farm holiday village we being allowed to erode as they see an SSSI.

17
Q

Hard engineering: Coastal defences at Minehead

Where is Minehead? Give some features…

A
  • North Coast of Somerset
  • One of the regions most popular tourist resorts
  • Home to a large Butlins resort, visited by thousands of tourists a year
18
Q

Hard engineering: Coastal defences at Minehead

Give background information.

A
  • 1990s- it became clear that the current sea defences would be inadequate
  • damage was estimated at £21 million if nothing was done
  • Work started in 1997 and finished in 2001
  • In total, it cost £12.3 million
  • Overall, it meant a label amount of money was saved from potential losses
19
Q

Hard engineering: Coastal defences at Minehead

Give features of the scheme.

A

a 0.6m high SEA WALL.

  • curved front to deflect waves
  • curved top to deter people from walking on it
  • the landward side was covered in attractive, local red sandstone

ROCK ARMOUR- placed at the base of the wall- to dissipate wave energy…

BEACH NOURISHMENT:

  • built up beach 2m in height
  • waves break out further out to sea- less erosion
  • good for tourists

four ROCK GROYNES
-to retain the beach and prevent longshore drift

A wide walkway with seating areas along side the wall
-popular with tourists.

20
Q

Keyhaven Marshes- a coastal habitat

Where are they?

A

South Coast of England.
In the western Solent in South Hampshire.
Behind Hurst Castle spit.

21
Q

Keyhaven Marshes- a coastal habitat

How have Keyhaven salt marshes been created?

A

They have formed behind Hurst Castle spit, which has formed because of longshore drift from the West.

  1. The spit provided a sheltered place for sediment accumulation and for eel grass to accumulate away from the impact of strong winds and coastal erosion.
  2. The pioneer colonising plant, eel grass, helps to stabilise the area further by trapping more sediment.
  3. Gradually, halophytes (salt tolerant plants) such as glass wort and sea blite colonise he accumulating mudflats.
  4. These plants trap more sediment and contribute organic matter when they die. These processes help the salty marsh to grow.
  5. Eventually the salt marsh will grow further and an even more complex set of plants will colonise the area, until the climax community of alder and ash trees is reached and a fully developed creek system. This is known as VEGETATION SUCCESSION.
22
Q

Keyhaven Marshes- a coastal habitat

What are the threats to Keyhaven?

A

GROYNES
Construction of GROYNES down current (to the west) which were designed to trap sediment for some of the south coast beaches… Starve the spit behind which the salt marsh ecosystem has formed and relies upon for shelter.
Human modification of the coastline had major ramifications for this ecosystem…
-spit has weakened
-at times spit has been breached by erosion.
Led to the die back of Spartina Anglica + threatens overall health of salt marsh.

Marsh is retreating by up to 6m a year.

SEA LEVEL RISE
-sea walls put in place—> marshes squeezed.

STORMS
December 1989- storms pushed part of the shingled ridge over salt marsh—> 50-80m exposed to sea—> eroded in less than 3 months.

ANIMALS graze- damages marsh

TOURISM is becoming increasingly important.
-increasing demands for leisure and tourism= further destruction —> careful management needed.

23
Q

Keyhaven Marshes- a coastal habitat

How is the marsh managed?

A

Sea wall- 1990s

SHORELINE MANAGEMENT PLAN-1996
Rock armour & beach nourishment
-550m of Rock armour at the western end of the spit.
-£5 million used to increase height and width of the spit in an attempt to stop breaching (300,000 cubic metres of shingle added).
Stabilises salt marsh…

SSSI- special site of scientific interest. Important site for wildfowl and wading birds.

Nature reserve- area is fully monitored and managed to manta in its biodiversity.
-access limited, development restricted.

24
Q

Keyhaven Marshes- a coastal habitat

Name some of the species at Keyhaven…

A

PLANTS- Cordgrass, Sea lavender

ANIMALS- wold spider, ringed plover, oyster catcher, common blue butterfly

25
Q

Soft Engineering: Wallasea island

What is Wallasea island?

A

A low lying coastal island.

Formed at the confluence of the River Crouch and River Roach.

Protected by a ring of embankment from the sea.

26
Q

Soft Engineering: Wallasea island

What was the used for in the past?

A

In the past, the island has been used for farming.

—> wheat grown.

27
Q

Soft Engineering: Wallasea island

What defences were previously used?

A

Ancient sea walls (400 years old)

28
Q

Soft Engineering: Wallasea island

How is the area managed now?

A

The government & environmental agency decided it is no longer cost effective to maintain defences.

MANAGED RETREAT is now occurring - creating the worlds biggest man made reserve.

  • £7.5 million scheme
  • 2006- the old sea wall was breaches in 3 places to allow 115ha of land to be flooded.

RSPB will manage the reserve
eventually the area will contain islands and salty lakes.
salt marsh—> breeding ground for birds.
The new mudflats and salt marsh help protect the new sea wall.

Geography Case studies (3 decks)

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