C -> 3.5-3.9

Question 1

how does vegetation stabilise sediment

Answer 1

o can reduce wind speeds - less aeolian weathering
o absorb water - less saturated sediment
o physically binds the sediment together - better resistance to winds or waves
o blocks water sediment for falling on top of the sediment - less erosion

Question 2

pioneer species for psammoseres

Answer 2

- xerophytic plants (dry tolerant)
marram grass and its 3m deep roots
- tough long and flexible leaves
- little water loss from transpiration
- fast growing (1m/yr)
- tolerates temperatures up to 60oC

Question 3

New York City

Answer 3

• hurricane sandy 2012, winds 90 mph
• Coastal flooding 14ft high
• 53 killed, $32bn damage, NY stock exchange closed
• 1 feet of SLR
• 4000ft of Brooklyn battery tunnel and other subways flooded
• 28 inchead SLR by 2100
• 20% properties have 26%+ chance of severe floods within 30 years

Question 4

why is there physical vulnerability

Answer 4

• SLR
• storm surges
• subsidence

Question 5

what are the human activities that exacerbate this

Answer 5

• mangrove deforestation (e.g. woods/ charcoal) which could reduce wave height (40% for first 100m) and stabilised sediment, and storm surges (0.5 per 1km)
• groundwater extraction, which causes subsidence
• river straightening (e.g. for navigation), so sediment is propelled offshore faster

Question 6

why local factors matter

Answer 6

• where is this a problem:
• US eastern sea board (coastline)
• one of the most populated coastlines, and particularly low lying
• 12% of the US live there

Question 7

lyme grass + marram grass

Answer 7

acts as a physical barrier to the wind

allows flocculation

Question 8

environmental determinism

Answer 8

study of how the physical environment predisposes societies and states towards particular development trajectories (i.e. nature controls human actions)

Question 9

storm surge

Answer 9

when low air pressures mean water expands out, meaning there is a larger volume of water so then, larger amounts of water from ocean pushed to the shore by wind energy from a tropical storm, combined with the tides and therefore increases water levels in an area temporarily.
this inundated the coastline

Question 10

12% of

Answer 10

worlds population live in low elevation zones (below 10km)

Question 11

bangladesh

Answer 11

• country at most risk from storm surges linked to tropical cyclones
• 40% of all recorded storm surges have occurred within bangladesh
• 60% of Bangladesh low lying - less than 3m sea level

Question 12

coastal mangrove forests

Answer 12

• they stabilise the coastal swamps and dissipate wave energy during tropical cyclones
• they are being cut

Question 13

triangular shape

Answer 13

of Bay of Bengal means it acts as a funnel for any incoming tropical cyclones or tides

Question 14

intense rainfall

Answer 14

from tropical cyclone contributes to flooding

Question 15

incoming tropical cyclones create

Answer 15

localised areas where atmospheric pressure is lower, thus meaning the weight of air is lowered and SLR creating a storm surge (1mb fall in pressure = 1cm SLR)

Question 16

wind speeds in tropical cyclones

Answer 16

known to reach up to 260kmh, which transfers more energy into waves and increases their height

Question 17

sea level is projected to rise

Answer 17

28-98cm within a century, with the most likely scenario being around 55cm by 2100, meaning 40% of Bangladesh’s farmland will be lost, vital coastal mangrove would also be destroyed

Question 18

2007 cyclone sidh

Answer 18

3m
260kmph
944mb
15k
1.7 billion

Question 19

What affects local coastal flood risk?

Answer 19

• Height means some islands are only just 2-3 metres above sea level and if winter storm waves are 5-7m high then land will be inundated
• Low pressure systems / typhoons cause sea water to bulge / produce stronger storm waves / break coral reefs / and inundates low-lying land
• Natural subsidence occurs because of the compaction of sediment under its own weight and this increases the chances of inundation
• If subsidence is higher then saltwater intrusion is more likely ruining freshwater aquifers and crops that depend on them
• Vegetation removal means protective natural barriers have gone and destructive wave energy is not dissipated.

Question 20

Key Climatic Changes:

Answer 20

• warmer océans - additional heat energy/ higher sea surface temperatures
• lower air pressure = faster winds/ higher doming of sea water
• larger storm waves

Question 21

• in Kiribati

Answer 21

• specific causes: SLR and storm surges
• SST changes bleach coral reefs (stress in polyps expels zooxanthellae (algae), leading to loss of food supply and colour
• responses include mitigation - solar panels and local food, adaptation - sea walls/ rainwater harvesting/ buying new land)

Question 22

Key climatic impacts:

Answer 22

• sea levels are rising (55cm by 2100)
• deltas are flooding
• more wind/ waves = more coastal erosion
• storm surges
• not tropical storms

Question 23

Key uncertainties:

Answer 23

• poor global data on average wind speed/ wave height
• poor forecasting
• human related drivers - eg. Land use change/ coastal development/ pollution
• more and more people in lowland coasts
• BUT: better protection and preparation

Question 24

And still, we are uncertain:

Answer 24

• We don’t exactly know what will happen to temperatures
• We don’t know how societies respond to crisis
• We can’t predict unusual combinations of factors

Question 25

Tarawa

Answer 25

- much of Tarawa (capital) is less than eight feet above sea level and risks being inundated as ocean rises - families from outer stools migrating to South Tarawa for jobs, education and healthcare, population more than 50k, newcomers forced to live in marginal areas prone to flooding by high tides - mangroves can’t stop the ocean, but the trunks and roots of mature trees reduce erosion and suppress storm surges, seedlings placed near Tarawa airport to stabilise the shore of the lagoon

Question 26

BWABWAI

Answer 26

Cultural damage as Kiribati food Bwabwai can not be grown to salt water incursion as a result of SLR, loss of subsistence farming

Question 27

mitigation

Answer 27

- solar panels on roofs | - local food - boycott western food to reduce emissions

Question 28

adaptations

Answer 28

- sea walls - to attempt to stop the waves - rainwater harvesting - so less risk of flooding - buying new land - fiji in 2012 bought 5500n for potential migration

Question 29

The Netherlands

Answer 29

- Very low lying (26% below SL) - Rhine Delta sediment - SLR of 19cm since 1900 - Subsidence of ~8mm/year - Combined with high tides - Sea inundated 17% of Holland’s land area. - Vulnerable population - projected increase in flood prone urban areas of between 30-125% by 2100.

Question 30

Differences between Netherlands and Bangladesh

Answer 30

* Netherlands is an extremely developed area with a high HDI * Bangladesh has the funnel coastline, which increases wave energy * Bangladesh deals with tropical cyclones * Bangladesh has a pop density 3x of Netherlands * Netherlands susceptible to mid latitude depressions

Question 31

Similarities

Answer 31

* Both are coastal countries * High population densities * Both on river deltas * Fluvial sediment present * Storm surges * Low lying with a region of land under sea level

Question 32

Economic impacts of coastal flooding in Netherlands

Answer 32

* Economic cost of almost £400 million * 10% farmland destroyed – 100k acres fertile land * While major portion of livestock dying – 200k+ * 6 assisting countries * 50k buildings damaged

Question 33

Social impacts of coastal flooding in Netherlands

Answer 33

* 72k people displaced * 1836 deaths * Transportation halted * Belongings lost/ destroyed during storm surges * Rise in unemployment * Impacts on mental health which can led to falls in worker productivity

Question 34

Environmental impacts of coastal flooding in Netherlands

Answer 34

- Livestock perishing - Land destroyed - Loss of habitats due to flooding - Soil becomes too saturated and full of salt to be used for agriculture

Question 35

Notes on Netherlands flood defences system

Answer 35

- large scale + top down, 1bn a year - Intentionally flood farmland to reduce sea level and relocate farmers to fertile land - Reclaim land using polders – 'low walled dykes’ - 2.8bn euros cost - Metal door system – open/closed depending on weather - For doors of dam to close – 3m above SL - 17 mil euros yearly cost

Question 36

How would this project work for Bangladesh

Answer 36

too economically intensive and exhausting for the relatively poor country Bangladesh. Not only would they struggle to source 17 million euros per year sustainably, high levels of corruption and political division existing in the country would make it difficult to implement this project efficiently. The limiting factor is its low HDI compared to Netherlands

Question 37

SLR affects disproportionate number of people as

Answer 37

many low lying coastlines like beaches are densely populated, low lying deltas tend to be extremely fertile and ideal for agriculture, also many river deltas support megacities, like the Ganges-Brahmaputra delta in Dhaka.

Question 38

Local factors which could influence flood risk of some coastlines:

Answer 38

height, subsidence, vegetation removal

Question 39

Height:

Answer 39

low lying coastlines only 1-2m above high tide, so at risk. New York = 20% properties have greater than 26& chance of being severely flooded within 30 years. Relative SLR has risen 12 inches for New York.

Question 40

Subsidence:

Answer 40

low lying coastlines in estuaries or deltas subject to natural subsidence through settling and compaction of recently deposited sediment. - Also can be caused by human factors - drainage of saturated sediment or groundwater abstraction like in Venice, weight of cities like in Venice. - In bangla, 50 large islands have subsided by 1.5m since 1960, due to isostatic crustal depression and due to water extraction by occupying populations.

Question 41

Vegetation removal:

Answer 41

salt marshes and mangrove forest reduce flood risk and trap sediment, raising height og land,. They also absorb wave energy. A 100m belt of mangrove forest estimate to reduce wave height by 40%, estimated 50% of worlds mangrove forest removed since 1950

Question 42

Bangladesh contains

Answer 42

190km sundarbans, largest mangrove forest ITW, but 71% is experiencing veg removal - some eroding at 200m/yr.

Question 43

Climate change coastal flooding

Answer 43

- Sea level will rise by 18cm - 59cm by 2100, combined changes in weather effects and sea level mean coastal erosion will increase. - Link of climate change to storm frequency and magnitude

Question 44

Hard engineering in general

Answer 44

- advantages = reassuring, one off solution can protect coastline for decades, stronger. - Disadvantages in general = high costs + maintenance, require very clever designed engineering solutions prone to got failure, coastlines made visually unattractive and needs of coastal ecosystems usually overlooked.

Question 45

Definition of soft engineering

Answer 45

attempts to work with natural physical systems and processes to reduce coastal erosion and flood threat In general - usually less on us and intrusive at coast

Question 46

Isostatic factors of change SL

Answer 46

- post glacial adjustment = post glacial rebound - subsidence - tectonics

Question 47

Subsidence and isostatic fall

Answer 47

deposition of sediment such as fluvial in large river delta = more weight, could lead to very slow crustal sag and delta subsidence lowering of water table from evaporation from CC = lower lying as pore water pressure removed.

Question 48

Tropical cyclones create

Answer 48

Areas of low pressure = storm surge = areas of low pressure generating surface winds that spiral into the centre of low pressure in an anti CW direction Low pressure = water particles expand = flood

Question 49

Link between CC and coastal flood risk - high confidence events

Answer 49

- SLR - 18-59cm by 2100 - pace and extent of SLR unknown due to human and physical factors like the carbon models, as well as adaptations and mitigations - delta flooding: increase in worlds major deltas cities coastal flooding by 50%

Question 50

Link between CC and coastal flood risk medium confidence

Answer 50

- increased wind speeds and larger waves - erosion will generally increase because of the combined effects of changes to weather systems and SLR

Question 51

Link between CC and coastal flood risks low confidence events (4)

Answer 51

- tropical cyclones might be larger by 2-11% by 2100, and associated rainfall will increase by 20% - cyclone intensity increase due to warmer ocean surface temperatures and warmed atmosphere holding more moisture - more intense tropical cyclones = even lower surface air pressure = even larger waves - polar front jet streams will accelerate = may increase number and intensity of depressions and SS in mid latitudes.