3.3 Coastal Risks Flashcards

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1
Q

What is Sea-level change?

A

Sea level is the average height of the ocean surface between high and low tide.

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2
Q

What the factors of short term sea level changes?

A
  • High and low tide alter local sea level.
  • Atmospheric air pressure low = rise in sea level.
  • Winds can push water towards coast.
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3
Q

What the factors of long-term sea level changes?

A
  • Isostatic change: local rise/fall in LAND level.
    -Eustatic change: global rise/fall in WATER level
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4
Q

What are storm surges?

A

Storm surge are short term rises in sea level caused by low air pressure.

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5
Q

What the factors of storm surges?

A
  • Depressions in Mid latitudes e.g UK
  • Tropical cyclones
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6
Q

What factors can make storm surges worse?

A
  • Strong winds push waves so height increases
  • High/spring tides occur.
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7
Q

What is the research done by IPCC?

Hint: Sea level changes statistics.

A

Sea levels rose by 3.2mm each year 1993-2010. If Greenland Ice Sheet melts, sea level could rise by 7m.

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8
Q

Maldives Case Study

A
  • 340,000 population
  • 1200 islands
  • Highest island is 2.3m above sea level.
  • If sea level rises by 50m, 77% of the land will be lost.
  • Malé has a 3m sea wall & artificial island Hulhmalé which cost $32M
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9
Q

Bangladesh Case Study

A

Bangladesh’s Coast is very vulnerable to flooding for a numebr of reasons:

  • Very low lying river delta (1-3m above sea level)
  • Storm surges meet river discharge
  • Intense rainfall from tropical cyclones
  • Unconsolidated sediment
  • Deforestation of mangroves
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10
Q

What is the examples of Isostatic Change?

A
  • Accretion: the weight of sediment causes land to sink
  • Tectonic Uplift: movement of tectonic plates may cause land to rise.
  • Isostatic Rebound: (post-glacial isostatic adjustment) after an ice age, glaciers will melt so land rises.
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11
Q

What are the example of Eustatic change?

A
  • Global Warming: when the ice caps melt, this extra water will flow into the oceans and raise sea level.
  • Global Cooling: water will be locked up in ice caps/glaciers, so sea level will lower.
  • Thermal Expansion: if temperature rises, water will expand, which makes sea level rise.
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12
Q

What is the Greenhouse effect?

A
  • This is a natural process that helps maintain a global temperature at 15°C
  • Around 30% of Sun’s radiation is reflected back into space.
  • The rest is absorbed or re-emitted by the Earth.
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13
Q

What is the Ice Age?

A
  • The last Ice Age was 16,000 years ago
  • North-West UK was covered in km^2 of ice, causing the land to subside
  • In South UK, the land rose to balance this.
  • As Ice melted around 10,00 years in Scotland the South-East is now sinking.
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14
Q

What are the case studies of tectonic activity

In terms of coasts.

A
  • Tectonically active regions (New Zealand) experience uplift as fold mountains are formed.
  • 1964 Alaskan Earthquake caused major changes to the coastline.
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15
Q

What are flood risk?

A

Places that are higher risk; are low lying coasts.

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16
Q

What are the factors of people that inhabit vulnerable coasts?

A
  • They are popular with tourists
  • Deltas & esturaries are good for trading with upriver places
  • Deltas are fertile & ideal for farming.
17
Q

What are the factors of erosional rate?

A
  • Long fetch & destructive waves
  • Structural weaknesses in cliffs
  • Cliffs that are vulnerable to mass movement & weathering.
  • Strong longshore drift
  • It can also be increased by HUMAN activity such as offshore dredging.
18
Q

What are Emergent Coastlines?

A
  • Created when sea level FALLS
  • Often have rocky coastlines with cliffs and flat raised platforms.
19
Q

What is a raised beach?

A

Wave cut platform higher than current sea level, not reachable by high tide.

Examples: West Coast of USA

20
Q

What is fossil cliffs?

A

Found behind raised beaches, have wave-cut notches & arches.

West Scotland - Isle of Arran

21
Q

What are submergent coastlines?

A
  • Created when sea level rises and floods the land
  • Often by river valleys or glacially-carved valleys.
22
Q

What is a Ria?

A

A river valley flooded with sea water, have a V-shaped cross section, common periglacial areas

eg South England

23
Q

What are Fjords?

A

A glacial valley flood with seawater, have U-shaped croos section, common in glaciated areas

eg West Norway

24
Q

What is a Dalmatian Coastline?

A

Formed where valleys lie parallel to each other and are flooded so only the tops are visible, making them look like islands.

eg Dalmatian Coast, Croatia