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Geog > C -> 2.10 - 2.13 > Flashcards

C -> 2.10 - 2.13 Flashcards

1
Q

west africa

A
  • 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
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2
Q

rising sea level guinea

A
  • 10cm since 1950
  • 1metre by 2100
  • $1.7 billion of loss for airlines
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3
Q

Coastal management Guinea

A

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

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4
Q

sand extraction guinea

A
  • removed from river
  • used for housing
  • sediment not transported to coastline
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5
Q

mangrove deforestation

A
  • used for fuel wood
  • to smoke fish
  • for fuel supply
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6
Q

diamond mining

A
  • gravel extracted from rivers
  • diamonds retrieved
  • gravel (sediment) not always returned
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7
Q

rock hardness

A
  • 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
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8
Q

geological orientation

A
  • 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
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9
Q

wave type/ energy

A
  • 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
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10
Q

rock breakdown/ erosion

A
  • eg, hydraulic action/ attrition/ abrasion, often together with other subaerial
  • some mechanical processes (solution and salt) expose the coastline to wave and subaerial processes
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11
Q

rock layers

A
  • differences within cliff face affects level of resistance, different rates of erosion, and over time cause landslides
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12
Q

wave cut erosion

A
  • 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
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13
Q

offshore dredging

A
  • removing material for ports/ beach nourishment

- deep water, energy retained

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14
Q

sea defences lead to

A
  • interruption of sediment transfer (longshore drift)
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15
Q

Egypt: CC impacts

A
  • 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
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16
Q

threat to mappleton

A
  • approx 50 properties and B1242 access road
  • soft boulder clay cliffs
  • fetch from Scandinavia
  • 1-2m/yr rate of erosion
17
Q

the decision (1991)

A
  • 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
18
Q

impact of the decision

A
  • Mappleton and the cliffs are no longer at great risk from erosion
  • this has increased erosion south of Mappleton
19
Q

west africa coastal stats

A
  • 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
20
Q

overall basic principle of erosion

A

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

21
Q

fetch

A
  • distance that waves travel uninterrupted

- longer fetch = faster retreat

22
Q

wind direction

A
  • largest waves from prevailing wind direction - SW in south wales
23
Q

depressions

A
  • low pressure weather systems
  • more intense, faster wind speeds
  • large destructive
24
Q

anticyclones

A
  • high pressure
  • calmer conditions
  • smaller waves
25
Q

tidal bulge

A
  • 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
26
Q

alignment strongest vs weakest

A
  • 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
27
Q

interaction perigean

A
  • 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)
28
Q

Trinidad coastline part 1

A
  • 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)
29
Q

Trinidad coastline part 2

A
  • 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
30
Q

economic losses

A
  • 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
31
Q

Environmental losses

A
  • 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?
32
Q

social losses

A
  • 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
33
Q

Recession rates influenced by geological factors as well as

A

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

Geog (52 decks)

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