The Coastal Zone Flashcards
What is a fetch?
A fetch is the length of water the wind blows over.
What is swash?
Swash is the movement up the beach by the wave.
What is backwash?
Backwash is the movement of the wave back down the beach.
What is the crest?
The crest is the top of the wave.
How is a wave formed?
In open sea, waves ‘bob’ up and down in a circular orbit. It does this because there is no friction from the sea bed. When the wave approaches the coastline, there is forward movement of the wave as it breaks and washes up the beach. It does this because there is no friction from the seabed which therefore slows down the base of the wave and the top of the wave carries on and spills over.
What is the movement of wave change from deep to shallow water?
In deep water, the waves do circular orbits in the water because there is no friction. Where as, when it gets to the shallow water, the friction from the seabed slows down the base of the wave and as the top is still going fast, it causes the wave to break.
What are the 4 characteristics of a constructive wave?
- small in height
- low energy
- strong swash
- weak bashwash
What are the 4 characteristics of a destructive wave?
- large in height
- high energy
- weak swash
- strong backwash
What is attrition?
Rocks and pebbles bump into each other to break apart and become smaller and smoother.
What is corrosion (solution)?
Where some cliffs that are made of rock dissolve in water.
What is corrasion (abrasion)?
When waves carrying sand and pebbles scrape away at the cliffs to make them smoother like sandpaper.
What is hydraulic action?
When waves break into the cliffs forcing air into cracks and blasting the rocks apart.
What is long shore drift?
The current which transports sediments such as mud, sand, and pebbles along the coastline. It is controlled by the direction of the dominant wind.
What is deposition?
When the sea loses energy, it drops the sand, rock particles and pebbles it has been carrying.
What is transportation?
Moving eroded materials, e.g. stones, sand or shingle by the waves from one place to another.
How are spits formed?
Overtime, long shore drift deposits sand and shingle in front of a river mouth/estuary. Due to the current from the river, the deposited sand and shingle can’t cover the river mouth, so instead is shaped.
How are bars formed?
Originally there are two headlands. Due to long shore drift the deposited sand and shingles join up the who headlands with a bar ad the water behind that is a lagoon.
What is a lagoon?
A lagoon is seawater with no current.
How are tombolos formed?
A tombolo is formed when long shore drift connects two islands together which deposited sand and shingle.
How are cliffs formed?
Cliffs begin to form when the destructive waves attack the bottom of the rock face between high and low water marks.
How are wave-cut notches formed?
Destructive waves attack the bottom of the rock face between high and low water marks. The waves erode the cliff face formed a wave-cut notch.
How are wave-cut platforms formed?
Weather weakens the top of the cliff.
The sea attacks the base of the cliff forming a wave-cut notch.
The notch increases in size causing the cliff to collapse.
The backwash carries the rubble towards the sea forming a wave-cut platform.
The process repeats and the cliff continues to retreat.
How are headlands formed?
Headlands are formed when the sea attacks a section of coast with alternating bands of hard and soft rock. The stronger rock resists waves attack longer and they therefore stand out as prominent rocky headlands.
How are bays formed?
Where rocks of different hardness and resistance to erosion meet the sea, the weaker rocks are eroded back more quickly to form bays.
What are the stages of caves, arches, stacks and stumps?
- Air and water gets into little cracks in the cliff side and this expands before breaking (hydraulic action). The expansion then forces the crack in the cliff to become larger before it expands into a cave.
- More erosion from the sea due to hydraulic power and corrosion then expands the cave into an arch.
- As the arch gets bigger and bigger from more hydraulic action, the top can no longer support itself and collapses forming a stack.
- Erosion attacks the bottom of the stack therefore making it smaller and weaker until it collapses leaving behind a stump.
Name an example of an rock in the caves, arches, stacks and stumps process?
Old Harry
What are the 3 types of management?
- hard engineering
- soft engineering
- managed retreat
What is hard engineering?
It involves artificial structures to control forces of nature. They are expensive, involve high maintenance costs, they’re destructive and unnatural.
What is soft engineering?
They are ‘low key’ with low maintenance costs. They are made out of natural resources.
What is the advantages and disadvantages of sea walls?
advantages:
- effective at stopped the sea
- often has a walkway for people to walk along
disadvantages:
- can be obstructive
- is unnatural
- very expensive and high maintenance costs
What is the advantages and disadvantages of groynes?
advantages: - results in a bigger beach - useful structures - not too expensive disadvantages: - often lead to increased rate of erosion elsewhere - unnatural
What is the advantages and disadvantages of rock armour?
advantages: - relatively cheap and easy to maintain - can provide interest to the coast often used for fishing disadvantages: - can be expensive to transport - don't fit in with the local geology - can be obstructive
What is the advantages and disadvantages of beach nourishment?
advantages: - relatively cheap and easy to maintain - blends in - increases tourists potential - bigger beach disadvantages: - needs constant maintenance
What is the advantages and disadvantages of dun regeneration?
advantages:
- maintains a natural coastal environment
- is relatively cheap
disadvantages:
- is time-consuming to plant the marram grass
- people don’t always respond well
- can be damaged by storms
What is the advantages and disadvantages of managed retreat?
advantages: - cheap option - creates a much needed habitat for wildlife disadvantages: - land will be lost if flooded - landowners will need to be compensated
What is the costs of sea walls, groynes, rock armour, beach nourishment, dune regeneration and managed retreat?
sea walls: up to £10m per km groynes: up to £5000 per metre rock armour: approx £1000-4000 per metre beach nourishment: approx £3000 per metre dune regeneration: approx £2000 per 100m managed retreat: £5000-10000 per hectare
