2B.9b Flashcards

Question 1

Q

What do storm surge events lead to?

Answer

A

Storm surge events can lead to severe coastal flooding with
dramatic short-term impacts (depressions, tropical cyclones).

Question 2

Q

WHy is bangladesh so low-lying and how fast is it subsiding

Answer

A

Bangladesh is on a very low lying river delta (largely <3 m) – it’s and still subsiding (8-18 mm/yr) due to sediment compaction.

Question 3

Q

Describe the water bodies near bangladesh

Answer

A

The Ganges and Brahmaputra river system has the third largest discharge in the world (30,770 m3 per second).
It also has the world’s largest suspended sediment load (1.84 billion tons per year).

Question 4

Q

Describe bangladesh’s two main cities

Answer

A

Bangladesh’s 2 largest cities (Dhaka and Chittagong) are located on the coast. >20 million people live there.
Chittagong is also the country’s main port (and source of GDP

Question 5

Q

What is special about the bay of bengal?

Answer

A

The triangular shape of the Bay of Bengal acts as a funnel for incoming water.

Question 6

Q

Why do tropical cryclones cause storm surges?

Answer

A

Tropical cyclones are areas of low atmospheric pressure. - - As air rises, the weight is lowered - sea levels rise to create a ‘Storm Surge’ (1 mb fall in pressure = 1 cm SL rise).

Question 7

Q

How do tropical cyclones create massive waves

Answer

A

Tropical cyclones bring intense rainfall and strong winds – they’ve been known to reach up to 260kmph (Cyclone Sidh in 2007).
-This also increases the wave height.

Question 8

Q

How does SLR affect bangladesh

Answer

A

Sea levels are projected to rise ~55 cm within a century. – - This means 40% of Bangladesh’s farmland would be lost. Vital coastal mangroves would also be destroyed

Question 9

Q

What defences do bangladesh have?

Answer

A

Engineered coastal embankments have helped to protect against storm surge and flooding since the 1960s.
Emergency shelters also provide safe evacuation points and can serve as schools

Question 10

Q

What defence has bangladesh lost?

Answer

A

-unconsolidated delta sediment can be easily eroded.
- Because mangrove forests have been deforested, there is little protection against waves, particularly during tropical cyclones

Question 11

Q

What is the early warning system

Answer

A

An early warning system (Bangladesh cyclone preparedness program) uses over 5000
volunteers to make people aware of oncoming cyclones

Question 12

Q

Describe the 1970 Bhola Cyclone

Answer

A

Storm surge height: 10m
Max 1 min sustained win speed: 205kmph
Lowest air pressure: 966mb
Deaths: 300,000-500,000
Economic losses: US$190 ML

Question 13

Q

Describe the 1991Cyclone

Answer

A

Storm surge height: 6m
Max 1 min sustained win speed: 250 kmph
Lowest air pressure: 918mb
Deaths: 139000
Economic losses: US$1.7bn

Question 14

Q

Describe the 2007cyclone sidr

Answer

A

Storm surge height: 3m
Max 1 min sustained win speed: 260 kmph
Lowest air pressure: 944mb
Deaths: 15000
Economic losses: US$1.7bn

Question 15

Q

Short term impacts of a low air pressure tropical cyclone

Answer

A

Deaths and injuries to people immediately through drowning or collapsing buildings
Subsequent deaths from hypothermia (homes destroyed), water borne diseases (sewer systems and freshwater pipe destroyed), natural causes (transport routes to medical care cut)
Destruction of infrastructure - roads, railways, ports, and airports flooded or destroyed
Damaged water pipes, electricity transmission lines and sewage systems - no power or water.
Homes destoyed - older houses worse standards, cheap in poor areas - homes on marginal low lying land (slums and shanty towns) most vulnerable - reconstruction may take several years, richer (insurance) likely to be rehoused first
Businesses destroyed - factories, offices - loss of power, interruption of raw material delivery, workers killed/injured/can’t get there - agricultural land contaminated - crop harvest lost