COASTS Flashcards
(115 cards)
1
Q
Opportunities for people living on coasts (6)
A
- 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
2
Q
hazards for people living on coasts (3)
A
- 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
3
Q
what are mangrove swamps
A
salt-tolerant forests of trees and shrubs that grow in the tidal estuaries and coastal zones of tropical areas
4
Q
conditions that lead to the formation of mangrove swamps (3)
A
- low tide currents
- saline water
- warm temp (20º)
5
Q
threats to mangrove swamps (2)
A
- Many mangroves are being lost/ replaced by shrimp farms and rice paddies
- Population growth
6
Q
Why are coral reefs and mangrove swamps co-dependant
(3)
A
- 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.
7
Q
what are corals
A
tiny, marine animals called polyps that form reefs when they live in colonies in their millions.
8
Q
whats a coral reef
A
an ecosystem made out of corals
9
Q
why are coral reefs not formed in some areas of the ocean
A
- 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
10
Q
fringing reefs
A
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.
11
Q
barrier reefs
A
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
12
Q
atolls
A
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.
13
Q
coral reef benefits to people (3)
A
- provide food
- Attract tourists which raises economy
- Shelter lagoons that are used for ports and boating activities
14
Q
threats to coral reefs (6)
A
- 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
15
Q
why are rivers considered a threat to coral reefs
A
because they bring pollutants into the sea
16
Q
what are coastal sand dunes
A
ridges of sand that form on the back of beaches and at spits
17
Q
conditions needed for sand dunes to form (2)
A
- Strong prevailing winds
- Wide expanse of sand
18
Q
what causes embryo dunes to form
A
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
19
Q
why do only salt-tolerant plants grow on embryo dunes
A
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
20
Q
why do dune ridges form parallel to the shore
A
as embryo dunes increase in size, they disrupt wind flow, creating areas of reduced wind speed where sand is preferentially deposited. This encourages the for
action of larger dune ridges that run parallel to the coastline
21
Q
what role does marram grass play in the growth of larger yellow dunes
A
very important because it is resistant to the drought conditions that prevail.
22
Q
is the yellow mobile dune ridge often the lowest or highest
A
highest
23
Q
how is marram grass uniquely adapted to the conditions found on yellow dunes
A
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.
24
Q
are embryo dunes the youngest or oldest dunes
A
youngest
25
as you move further away the beach, what happens to the colour of the dunes
become less yellow an more grey
26
why do semi-fied grey dunes decline in height over time
wind erodes the top
of the dune, carrying away loose sand and particles. Plant roots. am also compact the sand and redistribute certain areas. Water runoff and heavy rainfall further erodes the dune, lowering its height
27
what are embryo dunes made up of
mostly exposed sand,
28
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
29
coral reef benefits to people (3)
- They provide food
- Attract tourists which raises economy
- Shelter lagoons that are used for ports and boating activities
30
CONDITIONS NEEDED FOR SAND DUNES TO FORM
- strong prevailing winds
- wide expanse of snd
31
what are the oldest sand dunes
fixed sand dunes
32
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.
33
the energy of a wave is determined by
its height and length
34
near the coast, are waves fast or slow
slow due to the shallow water
35
destructive waves
operate in storm conditions and are tall
36
backwash and erosion of destructive waves
strong backwash, weak swash and lots of erosion
37
constructive waves
operate in calm weather and are less tall. (less than 1m)
38
swash of constructive waves and erosion
strong swash, weak backwash and erosion is limited
involved with transport and deposition of material creating landforms
39
5 types of erosion
hydraulic action
abrasion
attrition
corrosion
wave pounding
40
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
41
what is abrasion
when pebbles grind along a rock platform like cliffs, much like sandpaper
42
attrition
when rocks grind against each other into smoother, smaller pebbles
43
corrosion
chemical action of sea on a rock
44
wave pounding
the weight of the pounding waves onto the rock
45
what is longshore drift
The movement of material, such as sand and stones, along a coastline caused by the movement of waves
46
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
47
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
48
what is a wave cut platform
a wide gently-sloping surface found at the foot of a cliff
49
what forms a headland
when a cliff is made from both hard and soft rock, and the soft rock becomes eroded
50
what forms between 2 headlands
a bay
51
what is a bay
land that curves inwards,The area where the soft rock has eroded away, next to the headland
52
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
53
what is a spit
a ridge of sand which extends out from the mainland across a bay)(extension of a beach)
54
what influences the direction of lonshore drift
direction of waves
55
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
56
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.
57
what is a bar
Formed when (sand) spits extend across a bay
58
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
59
tombolo is formed when
a sand spit connects an island to the mainland
60
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
61
an arch is formed when
the caves are eroded by abrasion and hydraulic action until they completely cut through the headland forming an arch
62
how is a stack formed
arch is eroded and the roof becomes too heavy so collapses, leaving a stack
63
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.
64
order of formation of crack, cave...)
crack
Cave
arch
stack
sTUMP
65
CRACKS ARE FORMED BY WHAT EROSION
hydraulic action and abrasion.
66
HOW IS A CAVE FORMED
As the waves continue to grind away at the crack, it begins to open up and form a cave
67
management methods
hard engineering and soft engineering
68
methods of hard engineering (5)
- sea walls
- gabions
- groynes
- revetments
- rock armour
69
sea walls do what
Large-scale concrete curved walls designed to reflect wave energy
70
advantages of sea walls
Easily made; good in areas of high density
71
disadvantages of sea walls
Expensive; life span about 30-40 years;
foundation can be undermined
72
what are revetments
Porous design to absorb wave energy
73
advantages of revetments
Easily made; cheaper than sea walls
74
disadvantages of revetments
Life span limited
75
gabions
Rocks held in wire cages absorbs wave energy
76
advantages of gabions
Cheaper than sea walls and revetments
77
disadvantages of gabions
small scale
78
groynes
prevent longshore drift
79
advantages of groynes
Relatively low cost; easily repaired
80
disadvantages of groynes
Cause erosion on downdrift side; interrupt sediment flow
81
rock armour
Large rocks at base of cliff to absorb wave energy
82
advantages of rock armour
cheap
83
disadvantages of rock armour
Unattractive; small-scale; may be removed in heavy storms
84
soft engineering methods of management (3)
beach nourishment
offshore reefs
managed retreat
85
beach nourishment
Sand pumped from sea bed to replace eroded sand
86
advantages of beach nourishment
looks natural
87
disadvantages of beach nourishment
expensive and a short term solution
88
managed retreat
Coastline allowed to retreat in certain places
89
advantages of managed retreat
Cost-effective; maintains a natural coastline
90
disadvantages of managed retreat
Unpopular; political implications
91
dune stabilisation
sediment is added and erosion is reduced by marram grass planting
92
barrier beaches are found where
a spit extends across a shallow bay leaving a lagoon which becomes a marsh
93
spits form where (3)
- across river mouths
- where the coast suddenly changes direction
- where tides meet calmer water
94
why do salt marshes form behind spits
because waves can't reach those areas
95
hard engineering is
building artificial structures which try to control natural processes.
96
soft engineering
here the natural environment is used to help reduce coastal erosion and river flooding.
97
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
98
types of dunes as you get further from the shore (4)
- embryo dunes
- fore dunes
- yellow dunes
- grey dunes
99
what does marram grass do
- has long tough roots which binds the sand together, allowing the dune to grow high
100
What are coastal sand dunes?
Coastal sand dunes are ridges of sand that form on the back of beaches and at spits
101
does marram grass grow quickly
yes
102
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
103
What conditions lead to the formation of mangrove swamps? (3)
- warm temperature (20º)
- saline water
- low itde currents
104
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
105
What are the main threats to mangrove swamps?
- Many mangroves are being lost/ replaced by shrimp farms and rice paddies
- Population growth
106
By what processes does the wind transport sand particles
Saltation and suspension
107
why do only salt tolerant species grow on embryo dunes
because they have a high tolerance to hard conditions
108
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.
109
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.
110
What causes semi-fixed grey dunes to develop
as vegetation slowly colonised younger dunes, stabilising the sand and changing the surface colour more grey
111
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.
112
restoration of dune strategies (3)
- fencing
- beach nourishment
- revegetation
113
113
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
114
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
