Rivers, Floods and Management - Bangladesh Case Study Flashcards Preview

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Flashcards in Rivers, Floods and Management - Bangladesh Case Study Deck (55)
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When is the wet season?

May to September


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


What brings intense precipitation and storm surges?

Cyclones from Bay of Bengal


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

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


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


Which glacier in himalayas contributed to flooding and how?

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


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

Human causes of flooding


Where did deforestation occur and why?

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


How did deforestation contribute to flooding?

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


How did urbanisation contribute to flooding?

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


How did global warming contribute to flooding?

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


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

10-15% increase by 2030


How much rice was destroyed?

2 million tonnes


Who lost their livelihoods?

Subsistence farmers


What infrastructure was damaged?

Railways, roads, embankments, irrigation system


What groups of people were most affected?

Poor farmers, landless labourers and slum dwellers


How many people homeless?

36 million (25% population)


How much untreated sewage escaped into water each day?

500,000 cubic meters


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


Describe early warning system put in place

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


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


What dates did Bangladesh have catastrophic flooding again?

2007 and 2010


Why is Bangladesh under greater threat?

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


How much is temp supposed to rise Bay of Bengal?

2- 4 degrees next 40 years


What rise in sea level would be catastrophic and why?

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