coasts Flashcards
(106 cards)
1
Q
what is a coastal environment
A
a zone where the land meets and interacts with the sea
2
Q
what is the result of coastal environment
A
interactions between the lithosphere, hydrosphere, atmosphere and biosphere.
3
Q
lithospere
A
solid land
4
Q
biosphere
A
living things
5
Q
atmosphere
A
air
6
Q
hydrosphere
A
water
7
Q
what is the submerged zone
below the low tide shoreline called
A
offshore
8
Q
what is the area between the low tide and high tide shorelines called
A
foreshore
9
Q
what is the area between the high tide shoreline and highest water line called
A
backshore
10
Q
how are coastal environments different
A
- how much they affect
- affected by natural processes and human activities
11
Q
why are coastal environments dynamic
A
constant influence of natural processes and human activities = coasts changing
12
Q
what are factors that affect the coastal environment
A
- Waves
- Tides and sea level changes
- Ocean Currents
- Geology
- Types of ecosystems
- Human activities
13
Q
what is a wave
A
a rising and falling movement of the water surface that is usually produced by winds blowing across the sea or ocean.
14
Q
how do waves affect the coastal enviornment
A
Energy from the wind is transferred to the water and it is this wind energy that helps shape coasts when the waves hit land.
15
Q
what are tides
A
daily alternate rise and fall in the sea level
16
Q
what causes tides
A
mainly by the effects of the gravitational pull of the moon and sun on the earth.
17
Q
tides affect _
A
- coastal erosion
- sediment transport
- sediment deposition.
18
Q
how do tides affect the coastal environment
A
- During high tides, waves reach parts of coasts that may not be subjected to wave action at low tides.
- Hence, at high tides, waves erode and transport more sediments away from larger parts of the coasts than at other times.
19
Q
Changes in sea level also occur over
A
an extended period of time
20
Q
what are currents
A
large-scale, continuous movements of water in seas and oceans
21
Q
how are currents produced
A
by a combination of winds, the Coriolis effect, water density and temperature differences in the ocean
22
Q
how do currents affect coastal environment
A
they are able to cause the movement of sediments along the coast.
23
Q
ocean currents carry
A
- cool water away from the Poles towards the Equator
- warm water away from the Equator towards the poles.
24
Q
how does this help
(ocean current)
A
help create milder climates in coastal environments.
25
what is geology
the arrangement and composition of rock found in the area.
26
describe how geology will influence the rate of erosion
- the composition of rocks determines their resistance to erosion
- hence coastal areas with more resistant rocks(granite, basalt) will face a slower rate of erosion as compared to areas with less resistant rocks(limestone, shale) will face a faster rate of erosion
27
what is rock composition
the hardness of rocks and their resistance to erosion
28
what does rock composition affect
rate of change along coasts
29
examples of more resistant rocks
- granite
- basalt
30
why are more resistant rocks better
will erode more slowly than less resistant rocks
31
examples of less resistant rocks
- limestone
- shale
32
Coastal processes that operate on coasts consisting of different types of rock result _
in coasts with different coastlines
33
what are coastlines
the outline or contour of a coast
34
in an ecosystem
communities of plants and animals interact with each other as well as the environment
35
examples of coastal ecosystem
- bays
- estuaries
- mangroves
- coral reefs
36
coastal ecosystem affects
rate of change of coastal environments
37
why are corals and mangroves important
provide natural barriers that help slow down the speed and impacts of waves on the coastline
38
how do human activities affect the coastal environment
People change coastal environments
39
examples of human activities
- living
- trading
- fishing
- engaging in recreational activities
- altering coastlines when build marinas and port facilities
40
how do people cause pollution in the coastal environment
dumping waste
41
how are waves generated
1. winds blow over the surface of the ocean
2. The friction from the wind causes the water particles near the surface to move in an orbit i.e., in a circular motion, which creates the waves.
42
what are the factors affecting wave energy
1. wind speed
2. wind duration
3. length of fetch
43
The higher the wave energy is
- the steeper the wave
- the shorter the wave period becomes
44
the faster, longer and further the wind blows over the sea
the stronger and larger the waves generated
45
what is wind speed
how fast the wind is blowing
46
what is wind duration
how long the wind blows
47
what is length of fetch
the length of the open water over which the wind can blow unobstructed
48
describe how the fetch affects the wave
a longer fetch means more energy can be transfered as wind will be able to blow over it for a longer time
49
the greater the fetch
the more energy the waves have
50
parts of a wave
- crest
- trough
- wave length
- wave height
- steepness
- frequency
- period
51
what is crest
highest part of a wave
52
what is trough
lowest part of a wave
53
what is wave length
horizontal distance from crest to crest/from trough to trough
54
what is wave height
vertical distance between the highest and lowest part of a wave
55
what is wave steepness
ratio of wave height to wave length
56
what is wave period
time taken to travel through one wave length
57
what is wave frequency
number of wave crests/troughs that pass through a point per second
58
how do waves break
1. When waves approach shore, the water depth decreases and the wave will start feeling bottom.
2. Friction reduces wave velocity, the circular loops of water motion change to elliptical shapes
3. As the wavelength (L) shortens, the wave height (h) increases.
4. the steep front portion of wave cannot support the water as the rear part moves over, and the wave breaks.
59
effect of waves breaking
turbulent water of the surf, where incoming waves meet back flowing water
60
what happens when waves approach the shore
1. seabed interrupts the circular orbital movement of the water
2. water becomes shallower, the circular motion becomes more elliptical
3. the crest of the wave to rise up and then eventually to topple on to the beach
61
what is swash
water that rushes up the beach
62
what is backwash
water that flows back towards the sea
63
2 types of waves
1. constructive
2. destructive
64
features of constructive waves
| (7)
- Low wave frequency (6-9/min)
- small and low waves
- long wavelength
- low wave height
- found on gentle beach gradient
- Swash is more powerful than the backwash
- Builds up coast by deposition
65
why do constructive waves have gentle slopes
- wave spent most of its time overcoming the friction with shallow seabed
- waves are weaker, cannot carry load
- deposition occurs
66
features of destructive waves
- High frequency (10-15/min)
- large and high waves
- shorter wavelength
- greater waveheight
- found on steep gradient
- Backwash is more powerful than the swash.
- Erodes away coast
67
why do destructive waves have steep slopes
- waves encounter friction with increasingly shallow water
- wave loses energy & slow down
- but waves behind keep pushing it forward
- forcing it to rise, collapse and breaks
- gravity forces waves to be pulled back into the sea
68
how do coastal processes affect coastal areas
| (3)
1. erosion
2. transportation
3. deposition
69
erosion processes
1. hydraulic action
2. abrasion
3. attrition
4. solution
70
what happens during hydraulic action
- Waves break against a rock surface by their sheer weight and power.
- trap air in the cracks in the rocks.
- air is compressed by the oncoming waves, exerting pressure on the cracks.
71
outcome of hydraulic action
As the air is repeatedly compressed, the rock weakens and breaks apart.
72
what happens during abrasion
- As waves break, sediments carried by waves, such as sand and rocks, are hurled against the coast.
- These sediments knock and scrape against the coastal cliffs.
73
outcome of abrasion
weakens the surface and breaks down the coast. Over time, the impact is powerful enough to undercut a cliff.
74
what happens during attrition
When rock particles carried by waves rub or hit against one another.
75
outcome of attrition
they break down into smaller pieces and become smoother and more rounded over time.
76
what happens during solution
Sea water reacts chemically with water-soluble minerals in coastal rocks and dissolves them.
77
outcome of solution
When solution of minerals occurs, rocks are weakened and eventually disintegrate.
78
what is the process that happens during longshore drift
1. Swash carries materials up the coast at an angle.
2. Backwash carries materials back to the sea at right angles to the coast.
3. Results in a zig-zag movement of sediments along the coast.
79
when does deposition occur
small or low energy waves do not have the energy to carry the load
80
how does deposition sorting happen
1. Swash brings all the materials onto the coast
2. Backwash transports the materials back towards the sea. Larger ones are deposited first, followed by smaller ones.
81
grain size
| (big-small)
1. pebbles
2. coarse sand
3. fine sand
4. clay
82
types of landforms
- erosional
- depositional
83
what are erosional landforms
- cliffs and shore platforms
- headlands and bays
- caves, arches, stack and stumps
84
formation of cliff and shore platforms
1. Wave erosion is concentrated along a line of weaknesses, forming a notch.
2. Prolonged erosion of the notch causes it to become deeper, forming a cave.
3. Further erosion of the cave causes the roof to collapse, and a steep cliff is formed.
4. Further erosion causes the cliff to retreat inland. A wave cut platform is formed at the foot of the cliff.
85
what is wave refraction
bend or a change of wave direction
86
cause of wave refraction
- Water waves travel faster on the surface of deep water than they do on shallow water
- The change in speed of the wave will cause refraction.
87
how is headland and bay formed
- in the deep water, away from the coastline, waves arrive undistorted
- as the waves begins to arrive at the coastline, the water becomes shallow and so the waves begins to be bent by wave refration
- as the waves reach the headlands first, they are still moving rapidly and are erosive
- as the wave is increasingly refracted, it bends towards the sides of the headland
88
formation of headland and bay
1. waves attack an exposed discordant coast where alternate bands of resistant rocks and less resistant rocks occur at right angles to the coast.
2. The coast is eroded unevenly due to the different resistance of the rocks. The more rapid erosion of the less resistant rocks forms the bay. The less rapid erosion of the resistant rock forms the headlands.
89
formation of caves, arch and stack
1. Waves attack a line of weakness to form a notch at the headland. Continued erosion of the notch enlarges the notch, forming a cave.
2. With continued erosion, the cave is enlarged. An arch is formed when the cave cuts through the headland or meets with another sea cave on the other side of the headland.
3. Weathering and mass wasting may cause the arch to become unstable and collapse. This leaving behind an isolated pillar of rock called a stack.
90
what are depositional landforms
beach
91
how are beaches formes
1. Wave refraction causes waves to converge at the headlands.
2. Erosion is concentrated at the headland.
3. Wave refraction causes wave energy to be dissipated at the bay
4. Materials eroded at the headlands as well as other materials carried by the waves are deposited at the bay.
5. The materials on the beach may be sorted, with the larger materials being deposited inland.
92
spit formation
1. The longshore drift transports material in a zig-zag fashion parallel to the coast Even when the coastline changes abruptly, longshore drift continues to transport material in the original direction
2. Overtime, the accumulation of materials will appear above the surface of water, resulting in a long narrow ridge of sand or pebbles with one end attached to the mainland, called the spit.
3. Wave refraction or occasional changes in wind direction may cause the free end of the spit to curve to form a hooked spit
93
what is spit
long narrow ridge of sand or pebbles with one end attached to the mainland
94
what is a cliff
refers to a steep and near-vertical rock surface found along coasts
95
why are coastal areas valuable
1. value of coastal areas
2. coral reefs
3. mangroves
96
what is coastal ecosystem
refers to areas where there are interactions between coastal enviornments and their plant and animal communities
97
benefits from the coastal ecosystem
- provisioning
- regulating
- supporting
- cultural
98
providing services
- products such as fish, seafood, water, timber and others.
- Communities near the coast can depend on catching seafood/algae for food, fish meal and fish oil. These products serve both as their main diet and as their source of income.
99
examples of what the coastal ecosystem provides
- fish and shellfish stocks
- harvestable seaweed
- sand and gravel
- energy
100
regulating services
- help regulate the coastal environment.
- help stabilize shorelines, prevent flooding and provide protection from storms and natural hazards.
101
examples of what regulating services coastal ecosystems has
- storm protection
- waste breakdown and detoxification
- carbon storage and climate regulation
- stabilise sediment
102
supporting services
- support the production of ecosystem services.
- They sustain a wide range of habitats, such as the mangrove habitat, coral reef habitat and beach habitat. These natural environments in which plants and animals live are valuable to people and the living creatures.
103
examples of what support services coastal ecosystem has
- food web
- nutrient cycling
- water cycling
- habitats for species
104
cultural services
- Coasts provide cultural services, which are non-material benefits such as recreational, aesthetic and spiritual benefits.
- Outdoor activities and tourism relating to coastal areas are common, including sea sports, leisure activities by the beach, beach resorts and eco-tourism.
- The sense of beauty people obtain from looking at coasts can provide a rich source of inspiration for art, folklore, national symbols, architecture, advertising and technology. Many coasts are places of scenic beauty that turn into major tourist destinations.
105
examples of what cultural services ecosystem has
- tourism
- seascapes
- science and education
- wildlife watching
- recreation
- health and well-being
- creativity and art
106
examples of how people use coastal ecosystems
- Fisheries and aquaculture
- Housing and transportation
- Tourism and recreation
- Ports, harbours and piers
- Wind farming
- Desalination
- Sand mining, salt extraction
- Waste disposal operations
- Oil refining
