A-Level Geography: Coastal Landscapes and Change EQ3

Question 1

2B.7 Sea level change influences coasts on different timescales.

What is eustatic and isostatic sea level change classed as?

Answer 1

Long-term - they will occur over thousands of years.

Question 2

2B.7 Sea level change influences coasts on different timescales.

What is eustatic sea level change?

Answer 2

A change in global sea level is usually due to a change in the volume of water in the oceans.

Question 3

2B.7 Sea level change influences coasts on different timescales.

What is isostatic sea level change?

Answer 3

A change in local land level, this results in a relative change in sea level.

Question 4

2B.7 Sea level change influences coasts on different timescales.

What causes a eustatic rise in sea level?

Answer 4

Interglacial periods cause a warming of the climate which melts snow and glaciers and more precipitation falls as rain. Rain and snow/ice melt runs off into the oceans, causing a rise in sea level (increased volume of seawater). The thermal expansion also contributes to rising sea levels.

Question 5

2B.7 Sea level change influences coasts on different timescales.

What is thermal expansion?

Answer 5

Eustatic rise is due to thermal expansion. Water expands when it gets warmer, and so the volume of water increases and as a result, sea levels increase. This is due to Global Warming.

Question 6

2B.7 Sea level change influences coasts on different timescales.

What causes isostatic rise in sea level?

Answer 6

Isostatic sea level change could be due to post-glacial adjustment (glaciers weigh down the land beneath, and so the land subsides until it melts). Tectonic activity (such as earthquakes and volcanic eruptions) may cause land subsidence, therefore causing isostatic sea level increase.

Question 7

2B.7 Sea level change influences coasts on different timescales.

What is an example of post-glacial adjustment?

Answer 7

For example, post-glacial adjustment for the UK after the Ice Age has caused Southern England to subside around 1mm per year and Scotland to rebound and increase around 1.55mm per year.

Question 8

2B.7 Sea level change influences coasts on different timescales.

How much did sea levels rise (in cm) between 1870 and 2010?

Answer 8

Sea levels rose by 21 cm from 1870 to 2010.

Question 9

2B.7 Sea level change influences coasts on different timescales.

How can tectonic cause a change in sea level?

Answer 9

• Tectonic activity can cause the uplift of mountain ranges and coastal land (at collision and destructive plate boundaries) and a resulting fall in sea level.
• Tectonics activity can also cause coastal subsidence - where a relative rise in sea level could be seen.

Question 10

2B.7 Sea level change influences coasts on different timescales.

What is an example of tectonics causing a change in sea level?

Answer 10

• Banda Aceh, Indonesia, following the 2004 Boxing Day tsunami.
• Tohoku, Japan earthquake and tsunami 2011 (e.g. Miyagi prefecture subsided by around 3m).

Question 11

2B.7 Sea level change influences coasts on different timescales.

What are the three types of submergent landforms associated with sea level change?

Answer 11

• Rias
• Fjords
• Dalmatian coasts.

Question 12

2B.7 Sea level change influences coasts on different timescales.

How are the three types of submergent landforms created?

Answer 12

• Rias - formed where river valleys are partially submerged. Wide and deep at their mouth.
• Fjords - formed from downed glacial valleys rather drowned river valleys. Shallow mouth formed by deposition of material.
• Dalmation coasts - formed in areas where valleys lie parallel to the coast, an increase in sea level forms a dalmatian coastline. Valleys are flooded, leaving islands parallel to the coastline.

Question 13

2B.7 Sea level change influences coasts on different timescales.

What are examples of rias, fjords, and dalmation coasts?

Answer 13

• Rias - Kingsbridge Estuary in Devon and Southampton Water.
• Fjords - Milford Sound in New Zealand.
• Dalmation coast - The east shores of the Adriatic Sea, in southern Croatia.

Question 14

2B.7 Sea level change influences coasts on different timescales.

What is the difference between dalmation coasts and flooded rias?

Answer 14

Dalmatian coasts are flooded river valleys that run parallel to the coast, whereas this is not the case for Rias. Rias also have a dendritic, treelike outline (although they can be straight and without significant branches).

Question 15

2B.7 Sea level change influences coasts on different timescales.

What are the two types of emergent landforms associated with sea level change?

Answer 15

• Raised beaches

- Relict cliffs.

Question 16

2B.7 Sea level change influences coasts on different timescales.

What are raised beaches?

Answer 16

When the fall in sea levels leaves beaches above the high tide mark.

Question 17

2B.7 Sea level change influences coasts on different timescales.

What are relict cliffs?

Answer 17

Cliffs that are above raised beaches are no longer eroded and slowly get covered by vegetation.

Question 18

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What is coastalisation?

Answer 18

The movement of people towards the coast. Despite having a high flood risk, may people move to the coast due to tourism, high-yield agricultural lands, or housing pressure. Coastalisation can increase the environmental vulnerability of these locals to flooding due to storm surges.

Question 19

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What is a storm surge?

Answer 19

A change in sea level resulting from variations in atmospheric pressure and associated winds. May be due to low pressure during a depression or tropical cyclone.

Question 20

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What are the factors that can exacerbate a storm surge?

Answer 20

• Subsidence of the land - through post-glacial adjustment.
• Vegetation removal - mangroves provide protection against extreme weather events like cyclones which are very common in the Bay of Bengal. However, due to pressure for land space, many mangrove forests are destroyed for tourism, local industry, or housing plains.
• Global warming - As the surface of oceans get warmer, it is estimated that the frequency and intensity of storms will increase, and so the severity of storm surges and flooding is also expected to increase.

Question 21

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What are the major socio-economic consequences to communities?

Answer 21

Some areas of the coast may have significantly reduced house and land prices (as the area becomes known to be at significant risk). This can lead to economic loss for homeowners and local coastal economies. In the UK, many insurers don’t provide home insurance to people living along coastlines that are at extreme risk of erosion or storm surges.

Question 22

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What are the major environmental consequences to communities?

Answer 22

Storm surges also damage the environment by destroying plant successions and damaging many coastal landforms. Depositional landforms, due to their unconsolidated nature, are most likely to be destroyed. Also, erosion may take place at accelerated rates or higher up along the cliff face, which can increase the risk of collapse.

Question 23

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

Globally, how many people live on coasts?

Answer 23

Globally, more than 1 billion people live on coasts that are at risk from coastal flooding and 50% of the world’s population currently live within 200km of the coast.

Question 24

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

As storm surges increase, what will likely happen to those who live by coasts?

Answer 24

As storm surges and erosion along some coastlines are predicted to increase, so too is the volume of environmental refugees displaced internally or internationally. People may lose their homes, way of life and culture as they are forced to migrate to avoid the rising eustatic sea level and the rising risk of coastal flooding.

Question 25

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What are the economic consequences of coastal recession and flooding?

Answer 25

• Loss and damage to homes, businesses and farmland (losses tend to be localised).
• If area become depopulated, economic loss if businesses relocating.
• Falling property values and inability to sell.
• Insurance does not cover all costs
• Estimated 800 properties lost by 2035.
• South Devon Main Line Railway at Dawlish: a section of rail was destroyed in 2014. Repairs cost £35 million, with coast to SW businesses estimating up to £1.2 billion.

Question 26

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What are the social consequences of coastal recession and flooding?

Answer 26

• Costs to relocate: Breaks up communities, stressful, expensive.
• Loss of livelihood: Source of income, financial problems and job searching is stressful.
• Loss of amenity value.

Question 27

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What are the environmental consequences of coastal recession and flooding?

Answer 27

Loss of coastal ecosystems and habitat although this is no significant as ecosystems are already adapted to erosion

Question 28

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What is the strongest evidence that climate change will increase coastal flood risk?

Answer 28

• Sea level may rise to 18-59cm by 2100, but the pace is uncertain due to population growth, economic development, political commitment to GHG emissions.
• We can adapt to sea levels and storms with various defences e.g. storm surge barriers across river mouths, like the Thames Barrier.

Question 29

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What is some evidence that climate change will increase coastal flood risk?

Answer 29

Some evidence suggests increase wind speed and large waves, which will increase coastal erosion.

Question 30

2B.9 Coastal flooding is a significant and increasing risk for some coastlines.

What is low evidence that climate change will increase coastal flood risk?

Answer 30

• Tropical cyclones: frequency remain unchanged, but intensity would increase due to warmer ocean temps warmed atmosphere with more moisture, bringing strong winds and more rainfall.
• Storm surges: are linked to depressions that will become more common due to polar front jet streams accelerating. Also, tropical cyclones exhibit low surface air pressure, producing temporary sea level rise for storm surges.