2B.9 Coastal Flooding Flashcards

1
Q

give two example countries that are vulnerable to coastal flooding and why

A

Bangladesh and the Maldives
-due to their low lying land
-places are densely populated as beaches and the sea attract a large number of tourists
-low lying deltas are fertile and ideal for agriculture (Bangladesh)

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2
Q

how can height be a factor for coastal flooding?

A

-low lying coastlines are 1-2 m above high tide sea level
-temporary flood risks from storm surges and permanent flooding from global sea level rise

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3
Q

how can subsidence be a factor for coastal flooding?

A

-estuaries and deltas are subject to building and natural subsidence through the settling and com[action of deposited sediment
-human activity can cause local subsidence- via sediment drainage

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4
Q

how is Venice experiencing subsidence?

A

due to the weight of the city area and ground water abstraction for supplying cities, reducing sediment volume, leaving the ground to slowly sink
-sinking by around 1mm a year due to natural processes, humans are accelerating this though

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5
Q

how is the Fens of East Anglia experiencing local subsidence?

A

due to the drainage of saturated sediment and soil for agriculture
-currently protected by coastal defences, already much of it lies below highest tide levels

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6
Q

how is removing vegetation be a factor for coastal flooding?

A

it increases the vulnerability, as wave energy is dissipated less e.g. salt marshes and mangrove forest removal
-they stabilise existing sediment and trap it, raising height above sea level

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7
Q

Bangladesh sea level rise statistics

A

a 40cm rise would permanently submerge 11% of Bangladesh, creating 7-10 million environmental refugees

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8
Q

Maldives sea level rise statistics

A

a 50cm rise would permanently flood 77% of the Islands’ local area

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9
Q

Maldives main facts

A

has a population of 400,000 people, spread across 1200 islands
-highest point is 2.3m above sea level
-therefore very vulnerable to storm surges and erosion if levels rise
-removal of mangroves has increased flooding risks

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10
Q

Bangladesh main facts

A

one of world’s most densely populated countries
-46% of population live less than 10m above sea level
-people live in a delta of rivers, in the Bay of Bengal
-experiences heavy deforestation and monsoon on low-lying land
-subsidence has caused islands to sink by 1.5m in the last 50 years

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11
Q

The Thames Barrier in London

A

-one of the largest movable flood barriers in the world, spanning 520m across the river
-it protects 1.4 million people and 420,000 properties
-high rainfall has produced more prolonged flows

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12
Q

what can storm surges cause?

A

severe coastal flooding with dramatic short-term impacts

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13
Q

how are storm surges formed?

A

low pressure causes surface of the sea to rise temporarily
- surface winds spiral into the centre of the low pressure, causing depressions

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14
Q

storm surge

A

a temporary rise in local sea level produced when a depression, storm or tropical cyclone reaches the coast

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15
Q

named UK storm surge example date and location

A

5th December, 2013 in coastal East Anglia
-impacted Norfolk, Suffolk and Essex

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16
Q

December 2013 UK storm surge about

A

-the low pressure stream passed in the North Sea, near North Scotland
-29 severe flood warnings, 141 flood warnings and 63 flood alerts issued
-area of low pressure crossed the top of North Sea, pushing water southwards, causing sea levels to rise more over the shallow sea bed
-water was pushed into a narrow space, increasing wave height, with decreasing depth

17
Q

how does coastal morphology play a significant role in storm surges?

A

a shallow coastline slope produces a greater surge than a steeper slope, as the waves push the water inland faster than it can drain off via backwash

18
Q

name factors affecting the impact of a storm surge

A

-pressure (low pressure makes a higher surge)
-storm intensity/ wind power
-size of storm
-angle of approach (perpendicular is higher surge)
-shape of coastline (concave is higher surge)
-width and slope of ocean bottom
-local features e.g. barriers affecting flow of water

19
Q

how can winds and tides impact storm surge

A

-high winds ‘whip’ up waves causing them to be large and powerful
-high tides cause sea levels to be higher than normal- this is a natural factor

20
Q

impacts of Storm Xavier (Dec 2013) on the UK

A

-£1bn damage estimated across Norfolk, Suffolk and Essex
-80mph winds
-2 people died, 18,000 evacuated
-properties collapsed into the sea from erosion
-1400 homes flooded
-bridges shut and eastern railway services disrupted for a day
-£100 million total economic loss estimate

21
Q

cyclone in Bangladesh name and date

A

Cyclone Sidr in November 2007

22
Q

cause of cyclone sidr

A

low pressure (depression) sustems and high wind speeds

23
Q

about cyclone sidr

A

-category 4 cyclone
-240kmph winds
-6m storm surges

impact was worsened by intense rainfall, coastline from unconsolidated delta sediment is easily eroded, deforestation of mangrove swamps

24
Q

impacts of cyclone sidr

A

15,000 people killed
55,000 injured
1.6 million homes destroyed
-$1.7 billion total damage estimate
-roads, electricity lines, fresh water tube wells and crops destroyed

25
Q

adaptation

A

making changes to decrease the impact of flooding
e.g. sea walls, storm surge barriers, mangrove forest protection

26
Q

mitigation

A

efforts to reduce impacts of climate change
e.g. reducing greenhouse gas emissions

27
Q

what does IPCC stand for

A

The Intergovernmental Panel on Climate Change

28
Q

what is the IPCC

A

a global scientific authority that researches the link between climate change and coastal flood risk
-they believe that the impacts of climate change are hard to distinguish away form human related drivers

e.g. land use changes, coastal developments and pollution

29
Q

land use changes (impact of climate change)

A

energy production
-burning fossil fuels

industrial processes
-metal and steel works

agriculture
-machinery, cows, burning peats and wetlands which are carbon stores

30
Q

coastal development (impact of climate change)

A

subsidence from buildings, adding weight to land, sinks land
-especially vulnerable on rivers and deltas