Rivers Of Bangladesh (2) Flashcards

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0
Q

Drainage basin and water shed

A

Covers most of Bangladesh, parts of India, Nepal and China too
Watershed is made up of Himalayas and Tibetan plateau

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1
Q

The three rivers of Bangladesh

A

Meghna
Ganges
Brahmaputra

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2
Q

Brahmaputra

A

Covers 1000 kilometres (can’t cut through resistant rock of Himalayas)
Flood plain covers 50% of Bangladesh
Deposits sediment in its upper course and it erodes there too

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3
Q

Reasons why the river floods

A

Monsoon and snow melt
Deforestation
Overflow
Channel straightening and canalisation

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4
Q

Monsoon and snowmelt

A

Huge tidal waves and storm conditions
Waves reach 7m high and have very destructive effects
People are forced to live in flood plains, particularly the poor in islands in the delta

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5
Q

Deforestation

A

Lack of trees exposes soil to rain splash

Loosens particles in soil and produces surface runoff

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6
Q

Overflow

A

Increase in soil erosion increases amount of sediment deposited
Rivers in Bangladesh carry 1600 tonnes of slit per kilometres per second

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7
Q

Channel straightening / canalisation

A

Increases rivers speed and more water is carried faster downstream
However can be stopped by building levees that can prevent the water draining away quickly

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8
Q

Benefits to flooding

A

Farmers don’t mind them as although it brings disaster, it also provides a free fertiliser
Washes out salt from crops
Flushes out disease

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9
Q

Disastrous effects on flooding

A

Death of both people and animals
Destruction of homes and possibly whole islands of the delta
Death of fish populations ~ means poor diets as most people have 80% of their protein from fish

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10
Q

Are flood control schemes the answer

A

Sometimes the river floods despite having millions of dollars being spent on preventing this disaster

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11
Q

What are the schemes used

A

River straightening and levees
Dams
Tidal barrage across Bay of Bengal
Urban flood protection levees

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12
Q

River straightening and levees

A

Rise banks
Makes water difficult to drain away onto flood plain
Straightening can increase rivers power and carries floods away faster

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13
Q

Dams

A

Holds water back
May alter rivers flow
Slit gets tapped behind dam rather than in the flood plain

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14
Q

Tidal barrage across Bay of Bengal

A

Expensive
Protects land of the poorest people
Prevents water draining away freely
Reduces salt in the delta, making crops more reliable
But building up of chemicals and pesticides may occur

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15
Q

Urban flood protection levees

A

Protects the richer people
Reduces problems related to breakages in sewage
Reduces spread of disease

16
Q

Other methods of protecting people other than using flood control

A

Killas
Embankments
Satellite technology or warning systems
Urban flood protection

17
Q

Killas

A

House up to 1000 people
Concrete shelters for people and animals on stilts
Can shelter there for days
Cheap, easy to build, can help both poor and rich areas

18
Q

Embankments

A

Strengthen river banks
Structures up to 7m high
Expensive, restricted access to river for fishermen

19
Q

Satellite technology for warning systems

A

Increasing accuracy to predict when storms and floods are most likely to occur
Improves IT skills

20
Q

Urban flood protection

A

Targets most populated areas
Benefits richer people
Not necessarily protects from risks of pollution