Coastal flood risk

Question 1

Why is low lying coastal land densely populated?

Answer 1

• Coastlines are popular with tourists, especially where access to beaches and sea is easy
• Deltas and estuaries are ideal for trade
• Deltas and coastal plains are fertile for farming

Question 2

Examples of highly populated low-lying deltas

Answer 2

• Yangtze delta, Shanghai, 24 million people

- Indus, Karachi, 24 million people

Question 3

causes of coastal flood risks

Answer 3

• Sea levels rise increases flood and erosion risk
• Destruction of mangrove forests for wood and charcoal exposes coast to erosion
• River straightening means a faster river flow and sediment is moved too far offshore
• Storm surges from tropical cyclones flood the delta

Question 4

Storm surges

Answer 4

A localised, short term rise in sea level caused by air pressure change, 1mb fall in air pressure leads to 1cm sea level rise

Question 5

Islands at risk from coastal flooding

Answer 5

Maldives, population of 34000 people, highest point is 2.3m

- sea level rise would lead to 77% of Maldives disappearing into the sea.

Question 6

How have the people of the maldives attempted to protect themselves against coastal flooding?

Answer 6

• Built a 3m high sea wall around the capital city island

- Built an artificial island 1m higher than male

Question 7

What is the most common cause of coastal flooding?

Answer 7

• Storm surge

Question 8

What causes storm surges?

Answer 8

• a depression (low pressure weather system)

- Tropical cyclone (hurricane, typhoon)

Question 9

How do tropical cyclones and depressions cause flooding?

Answer 9

Strong winds push waves onshore, increasing height of the sea. High tides occurring at same, sea level will increase even more

Question 10

How can coastal topography increase the effects of storm surges?

Answer 10

Eg north sea, coastline narrows into a funnel shape, so storm surge is funnelled into a narrow space, so coastal flooding is severe

Question 11

Case studies of storm surges

Answer 11

• North sea 2013

- Bangladesh

Question 12

How will global warming affect sea level?

Answer 12

High confidence that sea level will rise between 28 and 98 cm by 2100, most likely rise is 55cm

Question 13

How will global warming affect delta flooding?

Answer 13

High confidence that the worlds major deltas at risk from coastal flooding is likely to increase by 50%.

Question 14

Global warming’s effect on storm surges

Answer 14

Medium confidence that storm surges linked to depressions are likely to be more common

Question 15

Global warming and coastal erosion

Answer 15

Medium confidence that erosion will generally increase because of the combined effects of changed to weather systems and sea level.

Question 16

The effect of global warming on tropical cyclones

Answer 16

Low confidence that the frequency of tropical cyclones will remain the same, but there could be more larger storms

Question 17

Global warming and Wind and waves

Answer 17

Some evidences of increased wind speeds and large waves