Flooding:

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?
Flooding Bangladesh
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• When water in a river channel overflows the banks.

What is a flood?
Impermeable soil or bedrock
Long periods of rainfall
Snowmelt
Sudden heavy rainfall
Intensive drainage systems
Insufficient vegetation cover
Why do floods occur?
Industry
Dams
Impermeable road surfaces
Deforestation
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Physical

• ?Sudden heavy rainfall More likely to occur in
  summer months when water is evaporated from soils
  leaving them hard and impermeable. Water is
  unable to infiltrate into the ground, river
  levels rise causing a flood.
• ?Long periods of rainfall Soils become
  saturated over time, excess water flows as
  overland flow into rivers, river levels rise
  causing a flood.
• ?Snowmelt Snow falls in winter and ground is
  frozen. In the spring snow begins to melt but the
  water is unable to infiltrate the soil as it is
  still frozen and impermeable. Therefore water
  flows overland and into rivers.
• ?Impermeable soil and bedrock These leave water
  unable to infiltrate into the ground causing
  excess overland flow into the rivers which causes
  the river level to rise.
• ?Insufficient vegetation cover when there is
  less vegetation less water is absorbed by plants
  so more water is infiltrated into the soil. Soils
  become saturated quicker causing more overland
  flow and as a result higher river levels.

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Human
?Road surfaces Rapid urbanization causes more
impermeable surfaces and decreases the amount of
permeable ground, therefore when heavy rains come
water is unable to infiltrate causing more
overland flow and higher river levels. ?Drains
These carry more water to rivers in a very short
time making river levels rise rapidly. ?Deforestat
ion Less vegetation means that less water is
taken in by leaves and roots causing the ground
to become saturated sooner leading to more
overland flow and rivers fill up quickly. ?Dams
Their main purpose is to control river levels,
but sometimes when it rains heavily they are
unable to cope and this may have devastating
effects. ?Industry Some industries add huge
amounts of water to rivers which causes very high
levels and lead to flooding.
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What caused the Bangladesh flood?
?Bangladesh is a country in Asia. ? It is located
at the mouth of two of the worlds longest
rivers, the Ganges and the Brahmaputra. ?
Bangladesh has floods every year but they seem
to be getting worse. ? The country relies on the
heavy monsoon rains to flood the rice fields, but
to much rain can destroy the crop as well as the
homes of the farmers. ? In four monsoon months,
Bangladesh can get as much rain as London gets in
two years.
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Tibet
H I M A L A Y A S
The Himalayas and Bangladesh get heavy monsoon
rain. The last few years have been wetter then
usual.
The number of people living in India and Nepal is
increasing. Trees
Nepal
?The loss of trees has increase the amount of
rainwater reaching the rivers.
? Bangladesh is a low flat country. 80 of it is
less than 6m above sea level.
? The Himalayas and Bangladesh get heavy monsoon
rain. The last few years have been wetter than
usual .
Brahmaputra
? The huge rivers brings the water quickly
towards Bangladesh.
Ganges
Confluence Point
? On reaching Bangladesh the rivers easily
overflow their banks. Large areas of land are
quickly flooded.
Bangladesh
Dhaka
? The population of Bangladesh is increasing
rapidly. More and more land is being covered in
buildings.
? The number of people living in India and Nepal
is increasing. Trees have been cleared to make
way for farmland and housing.
India
Bay of Bengal
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How does Bangladesh cope with flooding?

• ?Bangladesh suffers more from flooding than any
  other country in the world.
• The problem is made worse because of the extreme
  poverty of people who live there.
• In 1989, after a particularly bad flood, several
  wealthy countries joined with Bangladesh to set
  up the Flood Action Plan.
• Under the Plan, billions of dollars are being
  spent on schemes which it is hoped will reduce
  the risk and danger of flooding.

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The Flood Action Plan for Bangladesh
? Build dams to control river flow and hold back
the monsoon rain water in reservoirs. Stored
water can be used for irrigation and to generate
cheap electricity.
? Build embankments and deepen river channels to
stop the river overflowing . The embankments
would be up to 7m high in urban areas.
? Build 5000 flood shelters in areas most at
risk. These would be cheap to construct and
provide a place of safety for almost everyone.
They would be well stocked with food.
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Also. . .
? Improve flood warning systems. These would give
early warnings of floods. They would also give
instructions to people as to what they should do.
? Provide emergency help when the floods arrive.
Embankments would be repaired, people taken to
safety and food and medical care provided to
those in need.
? Give after-care once the flood ends. Food,
drinking water, tents, medicines and money would
be available. Help would be given to plant seeds
for ext years crops.
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? There is no easy solution to Bangladeshs
flooding problem. ? The enormous size of the
flooding problem and the shortage of money make
the task almost impossible. ? Even the Flood
Action Plan has not been welcomed by everyone. ?
Many people are worried that such a large scheme
could actually make the problem worse.
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Surma News Weekly
Dhaka 15 September 1998
Worst ever floods hit Bangladesh
The heaviest rains in living memory have left a
trail of destruction across Bangladesh. Estimates
suggest that over 7 million homes have been
destroyed and at least 25million people made
homeless. The official death toll is 2,779
although many more are still missing. More than
80 of the country is covered in water. In some
places only the tops of trees and buildings can
be seen. Railways and roads have been swept away
and Dhaka airport is still under water.
Delivering emergency food and medical care to
those in need has been almost impossible. Few
places have any electricity and there is no safe
drinking water. The threat of disease is
increasing and hospitals are already full of
people suffering from dysentery and diarrhoea.
Many of these people will not survive.
The countryside areas have been worst hit. One
family, sheltering on the corrugated iron roof of
their flooded home, had lost their two oldest
children to the flood. Their mother was in
tears. They were just washed away in the night
and never seen again. We have lost our homes,
lost our land and lost our cattle. Our crops have
been ruined and we have no food or money. Without
help we will starve. Please help us
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How can the risk of flooding be reduced?
? There are many different ways of controlling
rivers and reducing the risk of flooding. ? These
are called flood prevention screens because they
try to stop floods happening. ? Many people now
believe that complete river and flood control is
impossible. ? They say that flooding should be
allowed to happen as a natural event. ? Flood
prevention schemes can, in the long term, save
money. ? They also improve water quality and help
to support wildlife.
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Global Warming...
What will happen to Bangladesh if sea level
rises
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With a sea level rise of 7m this is what
Bangladesh will look like
Bay of Bengal
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With a further sea level rise to 14m Bangladesh
will probably no longer exist
Bay of Bengal
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References ?Waugh. D and Bushell. T. 2001. Key
Geography New Foundations. Nelson Thornes Ltd.
p.34-51 ?Flood Maps Website - http//flood.firetr
ee.net/