Hard engineering Flashcards

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1
Q
Dams
What are they?
How does it work?
Positives?
Negatives?
Examples?
A

They are huge walls built across rivers with a reservoir formed behind (artificial lake)

Flood water is caught by the dam, preventing flooding downstream. the water is then released at a steady flow throughout the year

Flood prevention
Production of electricity using HEP
Reservoir prodiges water for irrigation and used for recreational activities e.g. sailing

Reservoir created behind the dam floods the area, displacing, destroying farmland, disturbing wildlife
Traps sediment behind the dam, increased erosion
Dam failure

Hoover Dam, Lake mead formed behind, vital source of water in Las Vagas
3 Gorges dam China

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2
Q
Channel Modification
What are they?
How does it work?
Positives?
Negatives?
Examples?
A

Channels are modified to make them more efficient and able to transport water quickly

Meanders can be removed by building artificial cut throughs, or channels can be dredged to make it deeper and improve discharge capacity, shape + roundness building artificial smooth banks (concrete) or removing large boulders

Reduces flooding as the water will flow downstream quicker
Improves river navigation

Increased risk of flooding and erosional rates downstream
Disturbing wildlife habitats
Costly

River Derwent between Sherburn and Brompton in the vale of Pickering straightened throughout the 1800’s

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3
Q
Diversion channels
What are they?
How does it work?
Positives?
Negatives?
Examples?
A

Artificial river channels that take the water elsewhere if the water level is too high

Water is normally diverted around an important area or to another river

Prevents flooding as river discharge is reduced
Spillways have gates which open and close to control the release of water

Where a diverted river joins another river, discharge increases, flooding could occur below that point
If spillways are overwhelmed, water will flood areas not used to flooding

Town of high river, southern Alberts, Canada

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4
Q
Levee and flood plain modification
What are they?
How does it work?
Positives?
Negatives?
Examples?
A

Artificial levees or embankments built along the sides of a river to stop it being overwhelmed so easily

They allow the river to hold a greater discharge and floodplain to be built on
The height of the floodplain can be raised by dumping material on it

Stops overflowing so easily
Allows the river to hold a greater discharge and flood plains to be built on

Expensive- levees
If breached, can cause worse floods
Prevent water from draining back into a river

New Orleans, surrounded by artificial levees to protect the Mississippi River from flooding
Collapsed during the hurricane katrina causing devastating floods

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5
Q

What is a case study for hard engineering?

A

The 3 gorges dam

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6
Q

What are the characteristics of the 3 gorges dam?

A
2.3km long
Completed in 2006
Built across the Yangtze river
Generates electricity from HEP for central and Eastern China e.g. Shanghai
Huge Reservoir- 660km long, 1km wide
25 billion pounds to build
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7
Q

What are the positives of the 3 Gorges dam?

A

Social- Important symbol for China’s modernisation

Environmental- Burning 40 million tonnes of coal per year will be replaced by clean, environmentally friendly HEP

Environmental- Reduces CO2 emissions to the atmosphere by 120 million tonnes a year

Social- 15 million protected from flooding

Economic- Creates employment in the area

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8
Q

What are the negatives of the 3 Gorges dam?

A

Social- Reservoir flooded the homes of more than 1 million people

Environmental- silt trapped behind the dam, making farmland less fertile

Environmental- Habitats of rare and endangered animals such as Baji are disturbed

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9
Q

What is hard engineering?

A

Hard engineering defenses are man-made structures made to act against nature

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