Transcript Floods Hard and Soft Engineering

Managing Flooding
Hard and Soft Engineering
HARD ENGINEERING
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This uses technology, large amounts of
money to try and control the river.
It can prevent floods in the short term.
In the long term the river will try to get out of
this ‘straight jacket’ and the floods can be
made worse as a result.
Dams
Straightening (or channel realignment)
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Meanders are removed
from a river.
This means the water
has less distance to
travel and can therefore
be removed quicker.
However, it increases
erosion and flooding
downstream.
Straightening increases
the rivers efficiency.
Flood wall
Building up of levees
(embankments, flood walls, artificially
enhanced levees, revetments)
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The levees are widened and
heightened to increase the
amount of water a river can
carry before it floods.
They are often enforced with
concrete.
Flood magnitude may
increases due to the
increased amount of water
held.
Increased flooding upstream
and downstream, and
increased erosion
downstream.
SOFT ENGINEERING
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Often the cheaper option.
It tries to work with the river.
People seek to sustainably manage the river
– work with the river to stop large scale
damage from floods.
Afforestation
Planting trees.
 This soaks up water.
 Less surface runoff.
 Reduces flood risk.
Flood surrounding farmland
Flood farmland before waters get near the
city and homes and businesses.
Farmland is less costly to repair than houses
and industry.
Do nothing
It is an option.
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Allow an area to flood that is less valuable (in
other words not businesses).
What are the advantages of HARD
engineering?
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They will last a long time.
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There is good control of the river, especially
dams.
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People will feel safe.
What are the disadvantages of
HARD engineering?
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They can be very expensive.
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They are generally ugly/unnatural.
What are the advantages of SOFT
engineering?
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Allows the river to flow naturally.
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Makes good use of the land by the river.
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Environmentally good.
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Cheaper than hard engineering.
What are the disadvantages of
SOFT engineering?
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Farmland can be easily lost.
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Uses a lot of space.
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Could take a long time for maximum effect –
afforestation.
Today’s Task
1.
Thinking about the advantages and
disadvantages of hard and soft techniques
complete the worksheet.
2.
People have different opinions on flood
management.
Chose either the argument for or against
hard engineering schemes and explain
your reasons.