River Hard Engineering Strategies Flashcards
What is hard engineering?
Hard engineering involves using artificial structures to defend against natural processes.
What is the aim of hard engineering?
- To control the flow of rivers.
2. To reduce flooding
The costs for hard engineering can be (social….
Social
Economic
Environmental
What is the hard engineering strategy that involves building a concrete barrier over a river channel, and flooding the land behind it?
What does flooding the land behind it create?
The hard engineering strategy that involves building a concrete barrier over a river channel is building a dam.
Flooding the land behind it creates a reservoir.
What is a dam?
A dam is a concrete barrier, built across a river channel.
What is a reservoir?
A reservoir is an artifical lake behind a dam.
How is a reservoir created?
A reservoir is created by flooding the land behind the dam.
What does the reservoir do?
water is stored inside this reservoir
With the reservoir…
River discharge is released from the reservoir….
It is released in a controlled way.
With a reservoir, river discharge is released in a __________ way, reducing the _____ ____.
- controlled
- flood risk
With a reservoir, river discharge is released in a controlled way, reducing the flood risk.
Is water stored inside the reservoir?
Yes. Water is stored inside this reservoir and can be released in a controlled way.
With a reservoir, what happens if river discharge is too high?
If river discharge is too high, less water is released.
This reduces the flood risk, because the river is less likely to reach its bankfull capacity and flood.
Name one case study showing the effects (Costs and benefits) of a Dam and Reservoir.
An example of a case study is the Kielder Dam and Reservoir.
Name three costs of using a dam as a hard engineering strategy, using the Kielder Dam and Reservoir as an example.
Try to include facts and figures.
Three of the costs include:
Expensive to build: It can be expensive.
This one had a cost of £167 million to build.
Flooding: Land and settlements need to be flooded (to make the reservoir).
This displaced 58 families.
Farmland fertility: Farmland is less fertile downstream. Downstream, the river is less likely to flood, so rivers are less likely to deposit their fertile silt onto farmer’s fields.
Name three benefits of a dam, using a case study - the Kielder Dam and Reservoir as an example.
Try to include the facts and figures.
HEP: Hydroelectric power can be generated as water is released, through the reservoir.
This powers 11,000 homes.
Tourism: Tourism to reservoirs is popular.
This provides £6 million annually.
Forestry provides jobs and new habitats.
It provided 200 new jobs.
What is channel straightening?
Meanders are removed from the channel, and the channel is made wider, deeper and straighter.
What does channel straightening allow, that reduces the risk of flooding?
Channel straightening allows river discharge to flow away from the area more quickly.
This helps reduce the risk of a flood.
To make the channel wider, straighter and deeper…
To make the channel wider, straighter and deeper…
Concrete needs to be added to the channel.
This is to hold it in place.
If you think of a channel straightening image…
by removing meanders…
- The channel becomes straighter.
- River discharge can flow faster.
- This is because there’s less chance that it will back up and flood within the meanders.
- This, means the river can hold more discharge.
- .. which means it is less likely to reach its bankfull capacity and flood.
How does channel straightening help to prevent flooding? (1)
By removing meanders in the river, it makes the channel wider, deeper and straighter.
This allows river discharge to flow away from the area more quickly.
This reduces the risk of a flood.
How does channel straightening help to prevent flooding? (2)
By removing meanders, the channel becomes straighter.
River discharge is able to flow faster.
This is because there is less chance that it will back up and flood within the meanders.
This, means the river can hold more discharge.
… which means it is less likely to reach its bankfull capacity, and flood.
Channel straightening allows _______ _________ to ____ _______ from the area more ______.
river discharge
flow away
quickly
Channel straightening allows _____ _________ to flow ______ because there’s less chance that it will back up and flood ______ the meanders….
This means the river can hold ____ _________, which means that it is less likely to reach its ________ ________ and flood.
river discharge
faster
within
river discharge
bankfull capacity
flood
Name an example of a Channel straightening case study.
The River Valency in Boscastle, Cornwall
Explain the channel straightening of the river there. (What was the cost of the plan? What happened to the river?)
In Boscastle, the river was made wider, deeper and straighter as part of a £10 million management plan.
Try and explain three benefits of channel straightening, using the River Valency scheme as an example.
(HIN)
Habitat: New habitats can be created to try and make it look natural (River Valency is an example).
Insurance: Reduced insurance costs for nearby houses and businesses. (There is able to be this reduction in insurance costs because this strategy reduces the chance of flood damage).
Navigation: Improved navigation. Navigation can improve in rivers that have been straightened, because the boats can navigate the river more easily.