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