C -> 2.10 - 2.13

Question 1

west africa

Answer 1

• 700m of erosion in 40 years, particularly in NW guinea-bissau
• 10cm of SLR since 1950, 1m by 2100
• urbanisation high along coast
• fishing, tourism, commerce

Question 2

rising sea level guinea

Answer 2

• 10cm since 1950
• 1metre by 2100
• $1.7 billion of loss for airlines

Question 3

Coastal management Guinea

Answer 3

Added groynes, but ineffective as one end was not replenished, exacerbated this ends recession.

Question 4

sand extraction guinea

Answer 4

• removed from river
• used for housing
• sediment not transported to coastline

Question 5

mangrove deforestation

Answer 5

• used for fuel wood
• to smoke fish
• for fuel supply

Question 6

diamond mining

Answer 6

• gravel extracted from rivers
• diamonds retrieved
• gravel (sediment) not always returned

Question 7

rock hardness

Answer 7

• softer and uncemented sediment and rock are vulnerable to cliff retreat
• igneous rocks have a stronger crystalline structure where joints and fractures in the rock result in more complex coastal landforms

Question 8

geological orientation

Answer 8

• discordant coasts have different rates of erosion, resulting in headlands and bays
• headlands refract waves to concentrate wave energy, resulting in more complex erosional features

Question 9

wave type/ energy

Answer 9

• water is driven into the cracks in rocks, compressing air that is already there, creating an explosive blast
• bombardment and blasting is made worse by sediment thrown up in waves

Question 10

rock breakdown/ erosion

Answer 10

• eg, hydraulic action/ attrition/ abrasion, often together with other subaerial
• some mechanical processes (solution and salt) expose the coastline to wave and subaerial processes

Question 11

rock layers

Answer 11

• differences within cliff face affects level of resistance, different rates of erosion, and over time cause landslides

Question 12

wave cut erosion

Answer 12

• worn back cliffs leave shore (wave cut) platform, which cam be covered by the sea at low tide, resulting in further abrasion, limestone solutions and marine organisms creating a rocky foreshore (e.g. Glamorgan Heritage Coast)
• as platform becomes longer, wave attack on cliff base will decrease

Question 13

offshore dredging

Answer 13

• removing material for ports/ beach nourishment

- deep water, energy retained

Question 14

sea defences lead to

Answer 14

• interruption of sediment transfer (longshore drift)

Question 15

Egypt: CC impacts

Answer 15

• flooding of Alexandra
• 10% of nile delta flooded
• 7 million people displaced
• farming - less food, famine
• erosion of delta: SLR and more frequent storms, 5m/yr retreat
• water conflict
• cost of sea defences and loss of farmland

Question 16

threat to mappleton

Answer 16

• approx 50 properties and B1242 access road
• soft boulder clay cliffs
• fetch from Scandinavia
• 1-2m/yr rate of erosion

Question 17

the decision (1991)

Answer 17

• a coastal management scheme costing 2 million was introduced
• two types of hard engineering
• Norwegian granite rock armour along the base of the cliff
• built two rock groynes
• stopped beach material being moved south from Mappleton along the coast
• left withensea unprotected

Question 18

impact of the decision

Answer 18

• Mappleton and the cliffs are no longer at great risk from erosion
• this has increased erosion south of Mappleton

Question 19

west africa coastal stats

Answer 19

• 31% pop.live in coastal areas - 105 million
• 500k impacted by coastal floods annually
• 1.5 billion estimated cost of coastal protection
• 11bn expected annual damage from coastal floods by 2050s
• 296 million cost of degradation in Togo due to erosion and associated economic opportunity losses

Question 20

overall basic principle of erosion

Answer 20

rate of cliff retreat depends on amount of contact time between sea and rock

Question 21

fetch

Answer 21

• distance that waves travel uninterrupted

- longer fetch = faster retreat

Question 22

wind direction

Answer 22

• largest waves from prevailing wind direction - SW in south wales

Question 23

depressions

Answer 23

• low pressure weather systems
• more intense, faster wind speeds
• large destructive

Question 24

anticyclones

Answer 24

• high pressure
• calmer conditions
• smaller waves

Question 25

tidal bulge

Answer 25

- earth rotates on axis once every 24 hours - moon has gravity attraction - waves are pulled causing a bulge - laws of inertia counter act this, so bulge on opposite side of earth - bulges are aligned with moon as earth rotates

Question 26

alignment strongest vs weakest

Answer 26

- once a month (every 2 weeks) - spring high tides happen when sun + moon aligned, so pull is strongest - lowest high tides are NEAP tides, when sun and moon at right angles - weakest gravitational pull

Question 27

interaction perigean

Answer 27

- the moon takes 1 month to rotate around the earth - rotation is elliptical, which means it sometimes closer to the earth than others, and when closer, the gravitational effect is stronger - 4 times a year, this proximity coincides with the spring high tide, so you get an even higher spring tide (perigean spring tides)

Question 28

Trinidad coastline part 1

Answer 28

- small islands developing state (SID) - low lying and susceptible to current 0.06 m/yr rise in SL - 70% population live or work on coast - winter storms (nov-apr) from Atlantic have higher swell waves - affecting north and east coasts - NE-SW wind direction means east coast beaches are subject to southerly LSD - and subsuequently have highest erosion rates - esp. Coco Bay and Guayaguayare Bay (0.63m/yr)

Question 29

Trinidad coastline part 2

Answer 29

- coastal flooding along 20km of Manzanilla Beach in 2014 cuts off routes to SE (300m destroyed) - geology is mix of low grade metamorphic rocks, and weak sandstone and alluvium deposits - Mayaro is largest coastal development (community) - but Guayaguayare vital site of oil industry - main source of GDP and exports

Question 30

economic losses

Answer 30

- T&T is 3rd economy in Americas after US/CANADA - heavy depend on petrochemical industry of east coast(40% GDP,80% exports) - all major natural gas pipelines come ashore at Guya. site to serve rest of country (site of greatest erosion) - owing to lower economies of scale, infrastructure losses to erosion are more severe for SIDS - Manzanillo beach flood 2014 destroyed 300m of major access road - £5m cost - many luxury homes in Mayaro 700k+ - 400k+ tourists visited last year

Question 31

Environmental losses

Answer 31

- nesting sites for endangered leatherback turtles along north and east coast beaches - ecotourism - 16k acre trinity hills wildlife sanctuary and reserve on south coast has wealth of flora and fauna - ecosystems thought to adapt to small incremental changes of coastal erosion - so impact is smaller?

Question 32

social losses

Answer 32

- potential loss of coconut plantations which dominate east coast - also home to watermelon and vegetable cash crops (RISK: livelihood for inhabitants) - transport/ access affected by road damage during 2014 flood - RISK: commuters ant access oil and tourists industries - value of luxury coastal property likely to decrease over time with increased erosion rates - cost of relocation and break up of community more damaging for poorer locals - RISK: potential damage to existing hotel and tourist industry, eg Manzanillo beach facility - social tensions created by individual management attempts upstream which block LSD sediment

Question 33

Recession rates influenced by geological factors as well as

Answer 33

wind direction, fetch, tides, seasons and wearer systems and storms which determine wave intensity.