Coasts case studies

Question 1

Give an example of a high-energy coastal environment and a low-energy coastal environmental

Answer 1

HE - Dorset coast

LE - Persian Gulf

Question 2

(not to do with coasts but ah well) What is TVRA?

Answer 2

Trend, Variation (e.g. fluctuations), Range, Anomalies

Question 3

Where is Dorset located?

Answer 3

Southwestern coast of England (known as the “Jurassic coast”)

Question 4

Which factors are most important in shaping the Dorset coastline? Which are less important?

Answer 4

The most important factors are geology and wave processes. Aeolian processes, tides and sediment cells are less important.

Question 5

How does geology affect the coastal landscape in Dorset?

Answer 5

Contrasting rocks shape the coast
Differential erosion:
- Lulworth cove - wave processes exploit faults in highly resistant rocks through to lower resistance rock which erodes more quickly and outwards, forming a cove.
- Swanage bay - formed in area of discordant coastline (bands of different rock resistance perpendicular to the coast), where less resistant rock is eroded more quickly than the adjacent higher resistance rock, forming a bay between 2 headland - wave refraction enhances this effect (wave processes rather than geology)
Rotational slumping - Christchurch bay - large cliff sections slide and slip after heavy rain - made of soft layers of clay and sand

Question 6

How do wave processes affect the coastal landscape in Dorset?

Answer 6

Very large fetch (10,000km from Brazil) and strong prevailing south-westerly winds increase the size and strength of waves - they are destructive
Old Harry rocks - series of stacks and stumps formed by erosional wave action processes on a headland - wave refraction converges orthogonals, concentrating energy on sides of headlands, increasing erosion rates
Durdle door - arch formed by wave-action processes like hydraulic action and abrasion leading to the undercutting and erosion of a cave all the way through into an arch
Constructive waves create depositional landforms, for example there is a spit (hurst spit) that extends into the mouth of the Solent river (longshore drift)

Question 7

How do human processes affect the coastal landscape in Dorset?

Answer 7

Groynes prevent longshore drift at poole bay, as the economy here depends on attractive beaches (popular tourist destination) and the larger beaches also act as a form of coastal defence. This means there is less protective sediment further down the coastline (e.g. Christchurch bay, Barton-on-sea), called beach starvation - these areas are left more vulnerable to wave-action processes and erosion.

Question 8

How does climate change affect the coastal landscape in Dorset?

Answer 8

Submergent landforms - Poole harbour (ria), chesil beach (shingle beach)
Emergent landforms - Portland island

Question 9

Subaerial processes also shape and modify landforms along the Dorset coast (e.g. weathering and mass movements)

Answer 9

Yes they do, don’t they

Question 10

Where is the Persian Gulf located?

Answer 10

The Middle East

Question 11

What is the climate in the Persian Gulf?

Answer 11

Semi-arid climate

Question 12

What are the most and least important factors in shaping the coastal landscape in the Persian Gulf?

Answer 12

Most important are climatic, aeolian (wind) and tidal processes. Wave processes and geology are much less important.

Question 13

How do aeolian processes shape the coastal landscape in the Persian Gulf?

Answer 13

Longshore drift carries material eastwards
Prevailing North-westerly Shamal winds (strong) - lead to low, shallow wave crests, tombolos, reefs, mangroves, sand dune systems, tidal deltas - depositional features of low energy envrionments
Aeolian systems operate inland to form extensive dune systems - shamal winds - low lying sandy deserts
Abu Dhabi surrounded by numerous barrier islands (salt dome islands) and tombolos
Alluvial fans bordering the Hajar mountains
Barrier islands cause wave refraction which causes deposition on their landward side, forming tombolos

Question 14

How do tidal processes shape the coastal landscape in the Persian Gulf?

Answer 14

Microtidal range: <2m
Offshore tides - east to west - carry seidment shoreward onto the Sabkha, a characteristic feature of low-energy coastal environments in semi-arid climates.
Sabkha - supratidal flats of salts and mineral evaporites formed by deposition of material by tides in the microtidal range - found in hot and arid coastline climates - intense evaporation increases salinity
Anhydrite converted into gypsum by hydration reactions

Question 15

Where is Bacton located?

Answer 15

On the North Norfolk coast (20km south of Cromer)

Question 16

Why does Bacton require coastal protection?

Answer 16

It is the site of a very large gas terminal (Bacton gas terminal) that provides gas for a very large area of East Anglia - without it many people would be out of gas - very important for modern life in this country
This gas terminal provides hundreds of jobs, so without it many would be unemployed
It is of huge economic importance - creates a lot of income for the area
Must be protected from the erosion of the cliffs it is located on from marine processes - the cost-benefit analysis said it must be protected
One of the 3 main gas terminals in the UK
Cost over £15 million to build
Population of over 1100

Question 17

What are the methods put in place in Bacton to protect it from coastal erosion?

Answer 17

Groynes - prevent LSD carrying sediment away from the beach - sediment builds up on the beach, creating a larger and wider beach which absorbs the energy from waves hitting the coast, reducing the impact of marine processes such as hydraulic action and abrasion - protects the cliffs from erosion
Revetments - also build up beach and absorb wave energy
Rock armour - absorbs wave energy to reduce erosion of cliffs
‘Hold the line’ strategy, planned to become managed realignment

Question 18

What have been the intentional consequences of the methods and management employed in Bacton?

Answer 18

Gas terminal protected - means economic value and jobs are protected and people are provided with gas across the large area the terminal provides for
Houses and other buildings are also protected in Bacton

Question 19

What have been the unintentional consequences of the human management of the coastline in Bacton?

Answer 19

Management methods were put in place before the knowledge of sediment cells, one of which being the North Norfolk coast
Sediment is transported south by LSD, but the groynes and revetments used in Bacton prevent LSD. This means that further south along the coast, in Happisburgh, there is beach starvation (a deprivation of sediment, which would usually protect the area of coastline from erosion) as sediment is no longer being deposited in Happisburgh, but is still being transported away by LSD
This leaves the cliffs much more exposed to marine processes, and the cliffs in Happisburgh are already made of very weak clays. The cliffs are susceptible to very rapid erosion (average erosion rate 8-12m a year). Happisburgh cannot afford any coastal management strategies of its own and after a 2007 CBA the government ruled the DEFRA strategy as ‘no active intervention’
- Unintentional and very negative consequence of the human activities used to manage coastal erosion at Bacton
- There have been many protests in Happisburgh to try and bring more management or money from the government (e.g. SOS)
- Lighthouse has had to be moved several times, which has also cost a lot of money
- lots of mass movements such as slumping in happisburgh
- hard engineering

Question 20

Briefly describe intentional and unintentional consequences of coastal management in Sea Palling, North Norfolk

Answer 20

Protection required as Norfolk Broads (popular tourist destination) is behind - economical importance
Stepped + curved sea wall and offshore rock reefs put in place - hard engineering - deflect waves and absorb wave energy
Protection of beach and Norfolk broads, prevention of erosion
Tombolos formed (wave refraction + deposition behind rock reefs) leading to beach starvation