COASTS Flashcards
Opportunities for people living on coasts (6)
- It is very accessible. And the coastal harbours are used for ports,
- Fishing and food, marine life is a lot and people can also make a living from selling it
- Tourism, a lot of activities for people to do (boating)
- Agriculture, the soil will be fertile due to the water. (deltas)
- Ship building
- Salt marshes
hazards for people living on coasts (3)
- Natural disasters, tsunamis, tornados, hurricanes are more likely to happen near coats which causr the economy and population to decrease
- Erosion, erosion can lead to the retreating of land, making people move and cities being destroyed and houses to be destroyed.
- Rising sea temperatures, Rising sea levels mean that the area of land above the sea will be less, people will need to move/evacuate and at one point past towns will be submerged
For example in australia the ,marine life, sharks
what are mangrove swamps
salt-tolerant forests of trees and shrubs that grow in the tidal estuaries and coastal zones of tropical areas
conditions that lead to the formation of mangrove swamps (3)
- low tide currents
- saline water
- warm temp (20º)
threats to mangrove swamps (2)
- Many mangroves are being lost/ replaced by shrimp farms and rice paddies
- Population growth
Why are coral reefs and mangrove swamps co-dependant
(3)
- Mangroves protect coral reefs from sedimentation, as well as keeping the water clear from particles and nutrients ( this maintains the reefs health).
- Mangroves also provide a spawning nursery for the reefs species that will spend the rest of their lives there, and in return coral reefs provide shelter for the mangroves and their inhabitants
- The calcium carbonate eroded from the reef provides sediment in which the mangroves grow.
what are corals
tiny, marine animals called polyps that form reefs when they live in colonies in their millions.
whats a coral reef
an ecosystem made out of corals
why are coral reefs not formed in some areas of the ocean
- Because in some areas there are cold currents and corals need warmer temperatures to form - mostly this
- Because the sea currents are very strong and the coral reefs are not protected from the power of the water so cannot survive or form in it
fringing reefs
grow near the coastline around islands and continents. They are separated from the shore by narrow, shallow lagoons. Fringing reefs are the most common type of reef.
barrier reefs
also parallel the coastline but are separated by deeper, wider lagoons. At their shallowest points, they can reach the water’s surface forming a “barrier” to navigation
atolls
are rings of coral that create protected lagoons and are usually located in the middle of the sea. Atolls usually form when islands surrounded by fringing reefs sink into the sea or the sea level rises around them.
coral reef benefits to people (3)
- provide food
- Attract tourists which raises economy
- Shelter lagoons that are used for ports and boating activities
threats to coral reefs (6)
- Global warming, rising sea temperatures
- Rivers can be considered a threat to coral reefs because they bring pollutants into the sea
- Overfishing, not enough fish which mean that the ecosystem isn’t complete
- Boats and ships breaking reefs because of their movements
- destructive fishing practices using dynamite or cyanide destroying the reef
-mining coral for building materials
why are rivers considered a threat to coral reefs
because they bring pollutants into the sea
what are coastal sand dunes
ridges of sand that form on the back of beaches and at spits
conditions needed for sand dunes to form (2)
- Strong prevailing winds
- Wide expanse of sand
what causes embryo dunes to form
needs to be an obstacle blocking or slowing the wind down (like a plant) because of friction to deposit sand. The strong prevailing wind picks up dry sand and when it meets the obstacle it deposits the sand
why do only salt-tolerant plants grow on embryo dunes
Salt tolerant species grow on them because they have a high tolerance to hard conditions and act as the object causing the sand to be deposited due to the friction
why do dune ridges form parallel to the shore
Volume increase of the embryo dunes affects the wind flow pattern and creates preferential zones of sand erosion and deposition.
what role does marram grass play in the growth of larger yellow dunes
very important because it is resistant to the drought conditions that prevail.
is the yellow mobile dune ridge often the lowest or highest
highest
how is marram grass uniquely adapted to the conditions found on yellow dunes
grows upwards rapidly after being covered in windblown sand. It also has a network of very long roots that help to anchor the sand. The leaves and stems slow down the wind and protect the sand from erosion.
are embryo dunes the youngest or oldest dunes
youngest
as you move further away the beach, what happens to the colour of the dunes
become less yellow an more grey
why do semi-fied grey dunes decline in height over time
because these dunes are starting to build up more humus (the broken-down organic plant matter which is found in soil) from the diverse plant life and bacteria which now lives in these stable dunes. These dunes are also better at holding in water, making them able to support larger shrubs. These are also known as grey dunes and can still have sand blowing through them from blowouts, the semi-fixed dunes or even from the beach on a really windy day!
what are embryo dunes made up of
mostly exposed sand,
barrier reefs
parallel the coastline but are separated by deeper, wider lagoons. At their shallowest points, they can reach the water’s surface forming a “barrier” to navigation
coral reef benefits to people (3)
- They provide food
- Attract tourists which raises economy
- Shelter lagoons that are used for ports and boating activities
CONDITIONS NEEDED FOR SAND DUNES TO FORM
- strong prevailing winds
- wide expanse of snd
what are the oldest sand dunes
fixed sand dunes
What are dune slacks and why would the type of plants found in them differ from those found on the dunes themselves?
depressions in the dune system that have formed because of wind erosion down to the water table.
Long, marshy depressions, some with strips of water, lie between the dune ridges. These depressions are known as slacks. They contain water-loving plant species, which differ from slack to slack, because the ones further inland have more sediment deposited in them - leading to drier and less salty conditions for plant growth.
the energy of a wave is determined by
its height and length
near the coast, are waves fast or slow
slow due to the shallow water
destructive waves
operate in storm conditions and are tall
backwash and erosion of destructive waves
strong backwash, weak swash and lots of erosion
constructive waves
operate in calm weather and are less tall. (less than 1m)
swash of constructive waves and erosion
strong swash, weak backwash and erosion is limited
involved with transport and deposition of material creating landforms
5 types of erosion
hydraulic action
abrasion
attrition
corrosion
wave pounding
what is hydraulic action
lots of sea water crashes against the land and air and watr are trapped in rock cracks. water gets removed and the air expans, causing the cracks tog et bigger and the rock to break
what is abrasion
when pebbles grind along a rock platform like cliffs, much like sandpaper
attrition
when rocks grind against each other into smoother, smaller pebbles
corrosion
chemical action of sea on a rock
wave pounding
the weight of the pounding waves onto the rock
what is longshore drift
The movement of material, such as sand and stones, along a coastline caused by the movement of waves
when does longshore drift happen
when waves break at an oblique angle to the shore which means sediment and material is pushed up along the beach
coastal features of erosion- cliffs retreating
- waves erode rock along the shoreline by hydraulic action, corrosion, abrasion and pounding adn a notch is formed
- notch develops into a cave
- the rock above the notch becomes unstable and it collapses
- the coastline will retreat as this process continues to happen
what is a wave cut platform
a wide gently-sloping surface found at the foot of a cliff
what forms a headland
when a cliff is made from both hard and soft rock, and the soft rock becomes eroded
what forms between 2 headlands
a bay
what is a bay
land that curves inwards,The area where the soft rock has eroded away, next to the headland
waves are faster or slower where there are bays and faster or slower at headlands, why
FASTER at bays
SLOWER at headlands due to more friction
what is a spit
a ridge of sand which extends out from the mainland across a bay)(extension of a beach)
what influences the direction of lonshore drift
direction of waves
how does a spit form
- If the coastline changes direction, deposition begins to occur out into the sea
- This builds up overtime as the process of longshore drift continues
- Eventually leading to a formation of sandspit
- The spit can curve inwardly at the end due to wave refraction
why does a salt marsh form on a sand dune
The zone behind a spit becomes a sheltered area.A salt marsh then forms because the river deposits its sediment and the velocity behind the spit is much lower and there is much less wind and is protected from the waves
Some spits don’t form into bars because there is less distance to cover, it is shallower, the waves are better.
what is a bar
Formed when (sand) spits extend across a bay
how are bars formed
-due to the continued process of longshore drift
- Sand dunes with marram grass form to give stability to the bar
- Once closed off, the bay becomes a lagoon
- Over time a marsh land will form and rivers may enter the lagoon and deposit sediment
tombolo is formed when
a sand spit connects an island to the mainland
how is a tombolo formed
due to the continued process of longshore drift
The sand spit extends outwards into the sea and deposition builds up over time
Eventually the sand spit connects the island and mainland
Sand dunes with marram grass form over time giving it stability
an arch is formed when
the caves are eroded by abrasion and hydraulic action until they completely cut through the headland forming an arch
how is a stack formed
arch is eroded and the roof becomes too heavy so collapses, leaving a stack
how is a stump formed
stack is eroded and a wave cut platform is created, the stack then becomes too tall and heavy and collapses leaving the stump.
order of formation of crack, cave…)
crack
Cave
arch
stack
sTUMP
CRACKS ARE FORMED BY WHAT EROSION
hydraulic action and abrasion.
HOW IS A CAVE FORMED
As the waves continue to grind away at the crack, it begins to open up and form a cave
management methods
hard engineering and soft engineering
methods of hard engineering (5)
- sea walls
- gabions
- groynes
- revetments
- rock armour
sea walls do what
Large-scale concrete curved walls designed to reflect wave energy
advantages of sea walls
Easily made; good in areas of high density
disadvantages of sea walls
Expensive; life span about 30-40 years;
foundation can be undermined
what are revetments
Porous design to absorb wave energy
advantages of revetments
Easily made; cheaper than sea walls
disadvantages of revetments
Life span limited
gabions
Rocks held in wire cages absorbs wave energy
advantages of gabions
Cheaper than sea walls and revetments
disadvantages of gabions
small scale
groynes
prevent longshore drift
advantages of groynes
Relatively low cost; easily repaired
disadvantages of groynes
Cause erosion on downdrift side; interrupt sediment flow
rock armour
Large rocks at base of cliff to absorb wave energy
advantages of rock armour
cheap
disadvantages of rock armour
Unattractive; small-scale; may be removed in heavy storms
soft engineering methods of management (3)
beach nourishment
offshore reefs
managed retreat
beach nourishment
Sand pumped from sea bed to replace eroded sand
advantages of beach nourishment
looks natural
disadvantages of beach nourishment
expensive and a short term solution
managed retreat
Coastline allowed to retreat in certain places
advantages of managed retreat
Cost-effective; maintains a natural coastline
disadvantages of managed retreat
Unpopular; political implications
dune stabilisation
sediment is added and erosion is reduced by marram grass planting
barrier beaches are found where
a spit extends across a shallow bay leaving a lagoon which becomes a marsh
spits form where (3)
- across river mouths
- where the coast suddenly changes direction
- where tides meet calmer water
why do salt marshes form behind spits
because waves can’t reach those areas
hard engineering is
building artificial structures which try to control natural processes.
soft engineering
here the natural environment is used to help reduce coastal erosion and river flooding.
when does coral bleaching happen
when delicate corals become stressed due to factors including heat, causing them to lose their brown microbial algae, turning them white
types of dunes as you get further from the shore (4)
- embryo dunes
- fore dunes
- yellow dunes
- grey dunes
what does marram grass do
- has long tough roots which binds the sand together, allowing the dune to grow high
What are coastal sand dunes?
Coastal sand dunes are ridges of sand that form on the back of beaches and at spits
does marram grass grow quickly
yes
what are mangrove swamps
Mangroves are salt-tolerant forests of trees and shrubs that grow in the tidal estuaries and coastal zones of tropical areas
What conditions lead to the formation of mangrove swamps? (3)
- warm temperature (20º)
- saline water
- low itde currents
Why is conservation of mangrove swamps so important? (4)
- They provide large quantities of food
-Provide large quantities of fuel, building materials and medicine
- They protect coastlines from the force of storms and hurricanes
- They act as natural filters, absorbing nutrients from farming and sewage disposal
What are the main threats to mangrove swamps?
- Many mangroves are being lost/ replaced by shrimp farms and rice paddies
- Population growth
By what processes does the wind transport sand particles
Saltation and suspension
why do only salt tolerant species grow on embryo dunes
because they have a high tolerance to hard conditions
what causes embryo dunes to form
For coastal sand dunes to form, there needs to be an obstacle blocking or slowing the wind down (like a plant) because of friction to deposit sand. The strong prevailing wind picks up dry sand and when it meets the obstacle it deposits the sand.
why is marram grass so important
resistant to the drought conditions that prevail. Marram grass plays a important part in the growth of the dunes, because it grows upwards rapidly after being covered in windblown sand. It also has a network of very long roots that help to anchor the sand. The leaves and stems slow down the wind and protect the sand from erosion.
What causes semi-fixed grey dunes to develop
In time, dunes become a semi fixed grey dune, because humus from plant decay helps to form a soil and give them a grey colour
Why are dune systems vulnerable to damage by people and what can happen as a result?
Young dunes are very fragile, because marram grass cannot tolerate trampling.
When the grass dies, the wind easily removes the exposed sand. This leaves a depression or a valley like shape cutting right through the dune, called a blow-out.
restoration of dune strategies (3)
- fencing
-parallel foredunes - marram grass
Why do parallel lines of foredunes develop over time?
increasing volume of embryo dines affect wind pattern and created preferential zones of sand erosion and deposition
what is fencing
natural barriers against coastal erosion and flooding. Fences are installed on or around sand dunes to reduce wind speed and trap sand
