Rivers, Floods and Management - Bangladesh Case Study Flashcards Preview

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Flashcards in Rivers, Floods and Management - Bangladesh Case Study Deck (55):
1

Location

South-Central Asia

2

Frequency of major floods

Every 8 years

3

3 major rivers

Meghna
Brahmaputra
Ganges

4

Capital of Bangladesh

Dhaka

5

Population of Bangladesh's capital

Dhaka 1 million

6

How much rainfall fell in Bangladesh and when? This was the worst rain for how many years?

350mm in 24 hours
13th September 2004.
Worst rain for 50 years.

7

How much of Bangladesh is how far above sea level? Why?

20% less than 1 metre above sea level.
Because it is built on a floodplain on delta land.

8

Summary: 5 physical causes of Bangladesh flood

- Heavy rainfall
- Monsoon climate
- Low lying
- Himalayas
- 3 major rivers

9

What system was put in place for farming? Which river? Effects?

Irrigation system to divert the Ganges.
Reduced speed of flow in channels = more deposition inland, less on low lying delta = didn't build up

10

Name 2 places where urban growth occurred

Nepal and Tibet

11

Summary: 4 human causes of flood

- Irrigation diverted Ganges
- Urbanisation
- Deforestation of Himalayas
- Global warming

12

Deaths

800

13

How much of the country was flooded?

38%

14

How much of Dhaka was under water and in which month?

40% under water in July

15

How many bridges destroyed?

900

16

How much road damaged?

15,000 km

17

How much farmland destroyed?

800,000 ha

18

How many people suffered from diarrhoea in Dhaka?

100,000

19

Cost of total damage?

$7 billion

20

2 other long term impacts

Rice crops devastated = food shortages

Jute and sugar cash crops rotted = money shortages

21

How much aid did the UK give?

£21 million

22

How much aid did the UN appeal for? How much did they actually get?

Appealed for $74 million.

Only got 20% by September

23

What charity gave Bangladesh short term aid?

Water aid - water purification tablets

24

2 other short term responses

- NGOs: rice, clothing, medicine, blankets
- Farmers given free seed

25

9 long term responses

- Flood action plan formed
- Early warning system
- sluice gates
- 2 ha of raised land for flood shelter
- Coastal homes on stilts
- homes raised by 2m on earth banks
- Embankments strengthened
- Self help schemes: rebuilt homes & communities
- Additional financial aid granted

26

By how much were homes raised on earth banks?

2m

27

How much raised land was created for flood shelter?

2 ha

28

Date

2004

July---> September

29

What economic factor limits Bangladesh's ability to manage floods?

GDP per capita = $700 and tax revenue limited = rely on foreign aid and NGOs

30

Why did heavy rainfall lead to flooding?

Groundwater stores filled = water table reached surface = surface runoff

31

When is the wet season?

May to September

32

What causes rain to coastal regions? How did this lead to floods?

Low pressure and winds fro southeast = heavy rain
Meghan reached peak level in July

33

What brings intense precipitation and storm surges?

Cyclones from Bay of Bengal

34

What area of Bangladesh is easily washed away by floodwater and why?

Densely populated island - Chars
Made up of mud deposits = unstable

35

How did Himalayas lead to flooding? 3 ways

1. Snow and glacial melt increase discharge of Ganges and Brahmaputra

2. Tectonic uplift = rivers have more GPE = more erosion = sediment deposited downstream which chokes channels

3. Relief rainfall - high slopes = faster and more runoff

36

Which glacier in himalayas contributed to flooding and how?

Gangotri Glacier in Indian Himalayas feeds ganges. Melts at 25m per year.

37

what type of causes have become more important in recent decades?

Human causes of flooding

38

Where did deforestation occur and why?

In Himalayas due to pop pressure in Nepal and Tibet - need more grazing land and wood for fuel

39

How did deforestation contribute to flooding?

Less interception and evapotranspiration = more runoff
Soil erosion = river bed aggradation = reduced capacity

40

How did urbanisation contribute to flooding?

Impermeable surfaces = more runoff and less infiltration = discharge increased, lag time decreased.
Increased magnitude and frequency of flooding.

41

How did global warming contribute to flooding?

- More extreme weather = increased quantity and intensity of monsoon rain
- Higher temp = more snow melt

42

By how much is rainfall estimated to increase due to global warming and by when?

10-15% increase by 2030

43

How much rice was destroyed?

2 million tonnes

44

Who lost their livelihoods?

Subsistence farmers

45

What infrastructure was damaged?

Railways, roads, embankments, irrigation system

46

What groups of people were most affected?

Poor farmers, landless labourers and slum dwellers

47

How many people homeless?

36 million (25% population)

48

How much untreated sewage escaped into water each day?

500,000 cubic meters

49

5 environmental impacts of flooding

1. Land flooded
2. River bank erosion on embankments near main channels
3. Soil erosion
4. Waterlogged urban areas
5. Water Contamination

50

Describe early warning system put in place

- Satellite monitoring linked to local radio stations to send warnings
- warnings from loudspeakers in Mosques

51

Who and for how long was financial aid granted?

5 year period
- World bank loan to paid for infrastructure repairs, water resources management and education

52

What dates did Bangladesh have catastrophic flooding again?

2007 and 2010

53

Why is Bangladesh under greater threat?

Sea level rise and more storm surges
Climate change made cyclones more powerful = higher storm surges

54

How much is temp supposed to rise Bay of Bengal?

2- 4 degrees next 40 years

55

What rise in sea level would be catastrophic and why?

50-100 cm rise = 20% country flooded = 15 M refugees