Flooding in Bangladesh Case study notes
Bangladesh is one of the world’s poorest and most densely populated counties. 140 million people
live on the flood plains of the Rivers Ganges, Brahmaputra and Meghna.
Suffers from 2 types of floods:
1. River floods
 Occur every year due to snow melt and monsoons. Can be worse some years.
2. Coastal floods
 Created by Cyclones in Bay of Bengal which create a storm surge.
River Floods
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Yearly flooding due to the monsoons delivers tonnes of silt that add to the soils
fertility and makes it suitable for farming. This attracts people to the area. Flood
water is also used to irrigate the farmland and is important for agriculture.
2004 flood
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Monsoon arrived early and heavy rain fell from late June.
By early July the Brahmaputra and Meghna rivers have risen above their dangerous
levels.
A week later in July, the capital city of Dhaka had began to flood.
Food waters over toped many flood protection embankments.
Mid- August- flood areas have gone down leaving contaminated mud, and
destruction.
Effects:
 36 million people affected.
 1.5 million Women and children at risk from malnutrition.
 Killed 766 people
 Babies born to malnutrition women likely to suffer health problems.
Responses:
Preparedness programme: (bottom up approach working with local people.Soft engineering)
 Cluster villages were created- each village raised by 2m above water level. Each village
houses 25-30 people.
 Raised homestead- earth banks used to raise individual homes and planted with grass to
reduce erosion.
 Flood shelter – shelter 200 m above sea level and each shelter can accommodate 100
families.
 Rescue boats – located around areas of risk.
 Radios- given to ‘preparedness committee’ to give flood warnings.
Dhaka Integrated Flood Protection Project: (hard engineering)
 Slope protection to reduce the erosion of embankments that are built alongside the river.
 Storm drains built to link water back to rivers
 Sluice gates which are able to close when the channel water rises to hold back water from
key areas.
 Built a series of pump stations to remove flood water.
Case study questions you could get asked for this information:
1. For a named example you have studied, describe and explain the effects of a flood.
2. For a named example you have studied, explain how sustainable responses were to the
event.
Case Study – Boscastle Flood 2004
Boscastle had been affected by minor flooding events before 2004, but it was unprepared for a flood
of the scale that it experienced in August 2004. It is an example of a Flash Flood
Location:
Located within Cornwall which is South West England.
Causes:
Natural Causes:
 The catchment for the river is small and included impermeable land.
 Steep sided valleys converge as they run towards to sea, funnelling water into the river =
these factors lead to rapid runoff.
During the summer a number of unusual factors (these are known as antecedent conditions)
 Extremely wet summer and the ground was saturated.
 Heavy rain fell over 2 hours (1,400 million litres)
Human Causes
 Buildings have been built across the river
 Small bridges have been built over the river – these trap material reducing the flow of water.
 Artificially narrowing the river as it passes through the town to reduce carrying capacity.
 Removing vegetation from the sides of the valley (increase surface run off)
Effects
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25 business properties destroyed
50 buildings flood damaged
Cars within the car park were washed away down the town
4 footbridges washed away
Visitor centre destroyed (area relies in tourism so long term effect)
Stress and anxiety of local people
Insurance companies paid out an estimated £20 million to repair damaged property.
Responses
Boscastle Flood defence scheme was set up in 2006 as a response to this flood.
 Removed small stone wall over the river, built a wider, stronger bridge.
 River widened and deepened so it can carry higher flows of water. (upstream and near car
park)
 New flood defence wall was built.
 Raise car par areas so that cars are above a design flood level.
 Form wider river channel upstream of the car park to create an area of slower flow, where
larger sediment will deposit and the river can spread out. (working with natural processes)
Exam questions:
Using a named example for an MEDC flood you have studied, describe the flood defence scheme and
explain how it aims to reduce the impact of future floods.
Water Transfer Schemes
Context to why a transfer water scheme is needed:
The UK is highly variable in terms of water supply and demand. A lot of the rainfall received in the
UK falls in the North and West, whereas most people live in the South East. This means that the
north and west of the British Isles are water surplus areas, whilst the south east is a water shortage
area.
The north and the West receive more rainfall because the bulk of our weather comes from the South
West without prevailing wind. This brings moist air because the air is warm and has travelled a long
way over the Atlantic Ocean. The wet areas also coincide with our highland areas, as the wet
incoming air is forced to rise over these hills, and as it does so it cools, condenses and forms clouds
and then rain.
About the scheme:
 The main cities of Newcastle and Sunderland are on the east coast which is one of the driest
places in the British Isles.
 To combat this Northumbria water have constructed Kielder water.
 Kielder water is a management scheme designed to store water for the North East of Englad.
 The reservoir is in the north west of the region, so is in a high precipitation zone, and then
water is piped and run through rivers to the cities that have a shortage of water in the east.
 The area of Kielder receives 1700mm of water whereas Newcastle receives 644mm a year.
 Supply a population of 2.5 million
 It tops up the flow of water into the River Derwent when needed.
Advantages of the water transfer scheme
A hydroelectric power station, using the water
released by Kielder reservoir can generate
6MW of power.
The scheme includes 8 sites of SSSI, which
means unique plants and animals are
protected (e.g. red squirrel).
The lake is 11km long and stores nearly
200,000 million litres of water.
Huge volumes of timber are produced at
Kielder which employs 260 employees.
It can act as a flood prevention method as can
hold back water, reducing the flow in the River
Derwent.
£6 million is raised through tourism a year.
Disadvantages of the water transfer scheme
Reducing the flow of water from a river
changes the landscape of that river which can
affect plants and animals. A da holds back
sediment which means less riverbed in the
river affecting fish breeding grounds.
Clean water released from the dam has
increased the potential of erosion
downstream. (more acid= more solution)
58 families were displaced from their homes
by the dam, their houses disappearing beneath
the lake that was formed.
When the dam was completed if flooded an
area of scenic natural beauty.
2,700 acres of farmland was lost when the lake
was built.
The forest at Kielder has been criticized for
only having one species of tree (a coniferous)
as it grows quickly for timber.