Managing FloodingHard and Soft Engineering

HARD ENGINEERING

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)

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)

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

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.

Allow an area to flood that is less valuable (in other words not businesses).

What are the advantages of HARD engineering?

They will last a long time.

There is good control of the river, especially dams.

People will feel safe.

What are the disadvantages of HARD engineering?

They can be very expensive.

They are generally ugly/unnatural.

What are the advantages of SOFT engineering?

Allows the river to flow naturally.

Makes good use of the land by the river.

Environmentally good.

Cheaper than hard engineering.

What are the disadvantages of SOFT engineering?

Farmland can be easily lost.

Uses a lot of space.

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.