83 terms

IGCSE CIE Geography - Coasts

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Coast
The border between land and sea.
Why are coasts important?
Tourism
Sport
Ecosystem
Fishing
Oil / gas reserves
Housing
Industry
Transport
Walkers
Why are coasts under threat?
Rising sea levels
Pollution
Litter
Overfishing
Erosion
Tropical storms
Privatisation increases cost
Wave
Oscillations in water formed by the friction between the wind and the sea.
Factors affecting the size of a wave
Duration of wind
Strength of wind
Fetch (the distance travelled by a wave)
Crest
Top of a wave.
Trough
Bottom of a wave.
Wavelength
Distance between two crests / troughs.
Wave Height
Distance between crest and trough.
Wave Frequency
Number of waves per unit of time (generally minute).
Velocity
The speed that a wave is travelling at, influenced by wind, fetch and depth of water.
Swash
The movement of water and load onto the beach.
Backwash
The movement of water and load back down the beach.
Wave Refraction
As the wave reaches shallower water, the friction with the sea bed increases and thus the wave slows down.
If there is a headland, the waves slow down where the water is shallower, but continue to travel to the bay where water is deeper. As a result, the wave disperses its energy differently and contributes to the forming of a headland.
Destructive Waves
Waves with a weak swash and a strong backwash that erode and transport material away from beaches.
Constructive Waves
Waves with a strong swash and a weak backwash that deposit material on beaches.
Hydraulic Action
When sea water and air are trapped in the cracks of rocks, increasing the pressure and causing them to break apart.
Abrasion (Corrasion)
Rocks thrown against a cliff by waves.
Corrosion (Solution)
Acidity of the sea causes small particles to dissolve.
Attrition
Rocks and particles thrown against each other by the sea.
Wave Pounding
Immense power of waves crashing into cliffs, causing them to weaken.
Sub-aerial Weathering
Top of cliffs being attacked by the weather (wind, rain, heat, cold etc.), weakening it.
Bay
An indented area of land normally found between two headlands. Usually more sheltered so there is less erosion; beaches are commonly found.
Headland
A piece of land that sticks out into the sea that also causes waves to refract, forming additional features such as arches and stacks.
Wave-cut Notch
A small eroded hole at the bottom of the cliff formed by erosion.
Wave-cut Platform
The retreating of a cliff due to erosion, forming a low-lying platform.
Cave
A large area under a cliff, formed by erosion (mainly hydraulic pressure).
Arch
A cave eroded all the way through a headland.
Stack
When the roof of the arch collapses, forming two separate columns of rock.
Stump
Stacks eroded by the sea and wind.
Blowhole
When the sea erodes to the top of the headland, forming a large crack and hole.
Longshore Drift
Process of waves transporting material along a coastline.
Prevailing Wind
Direction a wind normally hits a coastline.
Groyne
Wooden or concrete fences placed out into the sea to reduce the impacts of longshore drift.
Sea Current
Movement of water caused by differences in temperature, changes in wind or tides.
Saltation
When small particles (e.g. rocks) are bounced along the beach due to transportation.
Tide
Movement of the sea in and out, twice a day, caused by the gravitational pull of the moon.
Intertidal Zone
Area of land between high tide and low tide.
Spring Tide
When the sun and moon are in alignment to each other, causing extremely high and low tides.
Neap Tide
When the sun and moon are aligned to each other perpendicularly, causing lower high and low tides.
Spit
Long, thin stretch of sand connected to mainland but stretching out into the sea.
Salt Marsh
A low energy, intertidal ecosystem that forms behind a spit containing some salt-resistant vegetation (halophytes).
Tombolo
A spit that joins the mainland with an island.
Mainland
Main landmass of an area.
Island
A small body of land found in oceans and seas.
Bar
A spit that connects two headlands or runs across a small cove / bay.
Lagoon
A salt water lake that develops behind a bar.
Changing Sea Levels
Sea levels are not constant, though currently it is rising. There are two types of sea level change.
Eustatic Changes
Global changes, when the whole level of the sea rises or falls. This is mostly affected by the amount of ice held in glaciers and ice shelves.
Isostatic Changes
Local changes, when the level of the land changes relative to the level of the sea.
Beach
Accumulation of material between the lowest spring tides and the highest spring tides. Material can be deposited from longshore drift, constructive waves and river discharge.
Berm
A ridge (long thin hill) that forms at the top of the beach where the strand line is.
Strand Line
A line of material (seafood, driftwood etc.) that is deposited by the sea at the furthest point of the high tide.
Sand Dune
Extensions of beaches that are formed by dry sand blown onto the beach.
Embryo Dune
Starting dunes of sand dunes, formed in the sheltered are between the berm and strand line.
Foredune
Small embryo dunes join together.
Yellow Dune
Small amounts of vegetation (e.g. sea couch and marram grass) begins to grow on foredunes.
Grey Dune
A developing humus layer starts to change the colour of the dune from yellow to grey.
Mature Dune
As the humus layer continues to grow, the dune can now support more vegetation, including flowers and trees.
Dune Slack
As the size of the dunes develop, water is collected between the dunes where marsh vegetation can grow.
Blowout
A depression or hole in the dune caused by the wind.
Humus
Layer of decaying plant or animal matter that adds nutrients to the ground.
Succession
Changing types of plants (e.g. from basic sea couch to trees).
Water Table
Line between saturated and unsaturated ground.
Hard Engineering
This building a physical structure, usually out of wood or concrete to protect the coast. This is usually more effective, but it can be very expensive and unsightly.
Examples of Hard Engineering
Rip-rap
Gabion
Groyne
Sea wall
Breakwater
Revetment
Soft Engineering
Working with nature to reduce the impacts of coastal erosion slightly.
Examples of Soft Engineering
Dune stabilisation
Cliff regarding
Beach nourishment
Beach drainage
Managed retreat
Cost-Benefit Analysis
It is not possible to protect the entire coastline of every country. Therefore, cost-benefit analysis is often carried out to see if the coast is worth protecting. The economic benefit of a coast will be looked at (e.g. how many jobs are in the area, how much tax the area pays, the value of the buildings in the area) and then the cost of protecting the area (e.g. how much a sea wall or rip-rap will cost).
Coral Reef
A line of limestone coral polyp found in warm, shallow areas.
Fringing Reef
Reef that circles the coastline or islands, often protected by barrier reefs further out to sea, so the plants and animals are suited to low wave-energy environments.
Barrier Reef
Reefs that occur further from the sea and are commonly separated from the mainland or island by a deep lagoon, normally older and wider than fringing reefs.
Atoll
Reefs that rise from submerged volcanoes and surround an island.
How coral reefs provide benefits
Support 25% of marine species (about 1 million species of plants and animals)
Protect coastlines from erosion
Natural barrier against tropical storms and tsunamis (they can absorb energy)
Natural recycling agent for carbon dioxide from sea and atmosphere
Contribute material to the formation of beaches (eroded coral reef)
Source of raw material (coral for jewelery and ornaments)
Many species are being found to contain compounds useful in medicine
Benefit the tourism industry because many people like to dive and snorkel over coral reefs
Important fishing grounds
High global value of coral reefs in terms of coastal protection, fishing and tourism: $375 billion.
How coral reefs are being damaged
Rising sea levels
Increases in the global climate
Hurricanes
Dynamite, cyanide and trawling fishing techniques
Deforestation
Overfishing
Tourism
Marine trade
How coral reefs are being managed
Ban damaging fishing practices
Conservation zones
Fish stocks can be enhanced and quotas imposed on amount being caught
Sewage outlets can be moved downstream of coral reefs
Banning the dropping of anchors on coral reef
Reduce the use of fertilisers near coral reefs
Alternative Names for Tropical Storms
Hurricane (North America)
Typhoon (East Asia and Pacific)
Cyclone (South Asia)
Temperature Required for the Formation of a Tropical Storm
27℃
Landfall
When a tropical storm hits land.
Formation
When an area of low pressure turns into a tropical storm.
Dissipation
When tropical storms breaks up and loses all its strength.
Eye
The centre of a tropical storm.
Saffir-Simpson Scale
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