Coasts Flashcards

1
Q

Four zones of coast

A

offshore
nearshore
foreshore
backshore

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2
Q

How do waves affect coastal environments?

A

Wave action
When wind blows across the surface of seas and oceans, energy from moving air is transferred to water surface to generate waves

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3
Q

What are tides?

A

Daily alternate rising and falling of sea level along coasts caused mainly by gravitational pull of moon & sun on earth

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4
Q

What are crest and trough?

A

Crest: highest part of wave
Trough: lowest part of wave

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5
Q

What are currents?

A

large scale and persistent movements of water in seas and oceans driven by prevailing winds which generally blow in one direction

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6
Q

How do currents affect coastal environments?

A

Distribute sediments as they carry large amounts of energy and shape coasts through the processes of coastal erosion, sediment transport and deposition

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7
Q

How does current produce milder climate in coastal areas?

A

They regulate temperatures by transporting cool water away from the north and south poles towards equator, and move warm water to the poles.

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8
Q

What happens to wave height and wavelength when wave breaks on shore?

A

Wave height: increase
Wavelength: decrease

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9
Q

What is swash?

A

When wave breaks and runs up on the beach

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10
Q

What is backwash?

A

When a wave retreats back to the seas

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11
Q

Constructive waves have…

A
  • low energy, deposit materials
  • strong swash, weak backwash
  • creates sandy beaches with gentle slopes
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12
Q

Destructive waves

A
  • high energy, break violently on shore
  • strong backwash, weak swash
  • coasts are eroded away
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12
Q

HEADLANDS OR BAYS?

Where do waves bend to?

A

BAYS

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13
Q

HEADLANDS OR BAYS

Where does waves diverge?

A

HEADLANDS

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14
Q

Name the 4 ways of coastal erosion

A
  1. Hydraulic action
  2. Abrasion
  3. Attrition
  4. Solution
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15
Q

Describe Hydraulic action.

A

Air may be trapped in cracks when waves crash
Trapped air is compressed repeatedly by oncoming waves
this weakens the cliff

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16
Q

Describe abrasion

A

Small rocks are hurled towards cliff by waves
They grind down the surfaces and weaken them

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16
Q

Describe Attrition

A

Waves smash rock and pebbles on shore into each other
They break up and become smooth and rounder

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16
Q

Describe Solution

A

Chemicals in seawater react and dissolves certain rock

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16
Q

Describe longshore drift

A

Currents flowing parallel to coast
Combined effect of sediment transport by beach drift and longshore current

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17
Q

Describe beach drift

A

zig zag movement along the beach due to swash and backwash

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18
Q

What is a cliff and how is it produced?

A

Steep and near vertical rock face along coasts
Produced by action of waves undercutting a steep rock coast

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19
Q

What are headlands?

A

Extensions of bedrock jutting out into the sea usually with a cliff

20
Q

Define Bays

A

Bodies of water connected to the seas due to surrounding land blocking off some waves

21
Q

Describe formation of headlands and bays

A

Waves move towards coast made of alternate strips of more and less resistant rocks
Softer rocks erode to form bays and harder rocks remain to form headlands

22
Q

What is a spit?

A

sand that sticks out into the sea but is joined to the land at one end

23
Q

What is the difference between tombolo and spit?

A

Tombolo connects 2 islands together

24
Q

How is spit formed?

A

Longshore drift carry material along coast
When there is a abrupt bend in coastline, longshore drift continues to transport materials the original direction
When material enter sea, deposition occur and accumulate and appear above water surface.

25
Q

How are caves formed?

A

Within headlands, there are some less resistant rocks, eroded faster.
Waves force their way into line of weakness such as joints/fault and undercut it

26
Q

How is arch formed?

A

Formation of caves then hollowed out by wave action some more

27
Q

How is stack formed?

A

When roof of arch collapse

28
Q

3 MAIN ways people use coastal area

A
  1. fisheries
  2. housing
  3. tourism
29
Q

Give example of how people use coastal areas for fisheries

A

Vietnam, Ca Mau
shrimp production centre, mangrove areas cleared
grown rapidly to US$800M in 2010

30
Q

Give example on how people use coastal areas for housing

A

Kukup, Malaysia
stilt house community, floating fish farms
sell fresh fish and other marine products and use boats as transport

31
Q

Give example on how people use coastal areas for tourism

A

Sentosa singapore
resort island with many recreational facilities
e.g. OneMarina club is a harbour with whafts providing maintenance for yachts and boats, recreational boating facilities

32
Q

Describe coral reef ecosystems

A

structure found at or slightly below sea level on seabed built by tiny animals aka coral polyps

33
Q

Describe the distribution of coral reefs

A

Mainly between Tropic of Cancer and Capricorn

34
Q

Conditions for coral reef growth

A

Sea surface temp: not lower than 17-18 DEGREES
Sunlight received: clear saline water required for algae photosynthesis
No sedimentation
moderate water motion for corals to receive oxygen

35
Q

Why are coral reefs important?

A

maintain natural ecosystem, supports more than 25% of earth marine species for breeding and growing
source of food and habitat
absorb wave energy

36
Q

5 ways corals are threatened

A

Overcollection of corals
Fishing methods
Climate change
Recreational use of coast
Coastal development

37
Q

Where are mangroves distributed?

A

Between tropic of cancer and capricorn

38
Q

What are some features of mangroves?

A

Aerial roots to take in air when they are not submerged
Prop roots to anchor them firmly in the soft mud
Javelin shape and buoyant fruit that is easy to germinate

39
Q

Value of mangrove in environments

A

Dense network of roots, stabilise shorelines, slow down water flow, build up sediments to protect coastal areas

40
Q

4 pressure ways that threaten mangroves

A

Coastal development
Conversion to other land use
Rising sea level
Increased demand for wood and charcoal

41
Q

5 hard engineering measures for coastal protection

A

Seawall
Groyne
Gabion
Breakwater
Tetrapods

42
Q

3 laws and regulation methods to manage coastal areas

A

Limit damaging activities
Protect coastal resource
Restrict development in areas prone to natural hazards

43
Q

3 Soft engineering measures

A

Planting vegetation and stabilising dunes
Beach nourishment
Encouraging coral reef growth

44
Q

Pros and Cons of beach nourishment

A

pros: transform coast into wide sandy beach, provides immediate protection to inland area
cons: time consuming & costly

45
Q

Pros and Cons of encouraging coral reef growth:

A

Pros: weaken wave energy & provide breeding ground for fish
Cons: rate of coral growth may be very slow

46
Q

Pros and Cons of planting vegetation and stabilising dunes

A

pros: roots hold sand firmly to the ground and prevent erosion
cons: takes time, costly to maintain dunes, non-resistant to natural elements and human elements e.g. vandalism&storms

47
Q

Pros and Cons of limiting damaging activities to manage coast areas sustainably

A

Pros: balance needs and demands of people to access or develop the coastal areas
EX building fences
Cons: beach becomes less attractive and prevent local people and visitors from accessing to all parts of the beach

48
Q

Pros and Cons of Seawall

A

Pros: absorb wave energy
Cons: require constant repair and is costly to build and maintain

49
Q

Pros and Cons of gabions

A

Pros: absorb wave energy better than seawalls , more effective in defending against high energy waves
Cons: unsightly, costly, corroded by seawater easily

50
Q

Pros and Cons of Groynes

A

Pros: absorb energy of waves so materials can be deposited on updrift side of groynes facing longshore drift
Cons:

51
Q

Pros and Cons of Breakwaters

A

Pros: break force of incoming waves, allows deposition and accumulation of materials to form beaches
Cons: unsightly costly, protect coast unevenly

52
Q

Pros and Cons of Tetrapods

A

Pros: can be used quickly to protect coast from wave attack, less likely to be damaged by waves
Cons: unappealing, costly, dangerous to beach users