Hard and soft engineering rivers

Question 1

Explain Dam & Reservoirs?

Answer 1

The flow of water can be ‘turned off’ during periods of heavy rainfall. The water is stored in a reservoir so that the river does not flood downstream.

Question 2

What are the advantages of Dam & Reservoirs?

Answer 2

• They are very effective at regulating river discharge (how much water is in the river)
• Most reservoirs can be used for irrigation, water supply, hydro-electric power, recreation

Question 3

What are the disadvantages of Dam & Reservoirs?

Answer 3

• Very expensive
• Many people must be relocated as the reservoir floods large areas of land.

Question 4

What are Embankments?

Answer 4

a raised riverbank (levee)

Question 5

What are the advantages of Embankments?

Answer 5

• Raising the level of a riverbank allows the river channel to hold more water.
• It is an effective way to reduce the risk of flooding.
• Can look natural if soil, mud, stones and vegetation are used.

Question 6

What are the disadvantages of Embankments?

Answer 6

• Expensive
• In urban areas concrete is often used to increase effectiveness. These are unattractive and unnatural.

Question 7

What is Channel Straightening?

Answer 7

rivers are straightened by cutting through meanders to create a straight river channel. This speeds up the flow of water along the river.

Question 8

What is the advantages of channel straightening?

Answer 8

The straight channel speeds up the flow of water. This prevents water building up and causing a flood. It is an effective strategy.

Question 9

What is the disadvantages of channel straightening?

Answer 9

• Expensive
• It can cause flooding further downstream as the water can quickly build up there where there is no channel straightening.
• Sometimes it is lined with concrete. This creates an unattractive and unnatural environment and can damage wildlife habitats.

Question 10

What are Flood Relief Channels?

Answer 10

A man-made river channel constructed to divert water in a river channel away from urban areas.

Question 11

What are the advantages of Flood Relief Channels?

Answer 11

• They are very effective at regulating river discharge (how much water is in the river)
• During times of high water flow, sluice gates can be opened to allow any excess water to flow away into the flood relief channel and reduce the risk of flooding.

Question 12

What are the disadvantages of Flood Relief Channels?

Answer 12

• Expensive

Question 13

What is Afforestation?

Answer 13

planting trees to establish a woodland or forest.

Question 14

What are the advantages of Afforestation?

Answer 14

• Trees slow down the movement of water into river channels (longer lag time).
• Water is soaked up by trees or evaporated during transpiration, reducing the amount of water being transferred to the river channel.
• It is relatively cheap and looks natural.

Question 15

What are the disadvantages of Afforestation?

Answer 15

Less effective than hard engineering strategies.

Question 16

What is Floodplain Zoning?

Answer 16

land is allocated for different uses according to its level of flood risk. Land closest to the river, at high risk, is used as parkland/playing fields. Land further from the river, at low risk, is used for housing and industry.

Question 17

What are the advantages of floodplain zoning?

Answer 17

• Reduces the overall cost of flood, as less expensive infrastructure is destroyed.

Question 18

What are the disadvantages of floodplain zoning?

Answer 18

• The flood still occurs and it can be difficult to implement on land already developed on.
• It can lead to a fall in land value next to rivers.

Question 19

What is Planning & Preparation?

Answer 19

rivers are monitored by satellites and instruments are used to measure rainfall and check river water levels. Computer models can then be used to predict discharge peaks and identify areas at risk of flooding.

Question 20

What are the advantages Planning & Preparation?

Answer 20

• The Environment Agency issue flood warnings.
• The EA make maps identifying areas at risk of flooding. People living in these areas can prepare for flooding (moving valuables upstairs, using flood gates and sandbags to keep floodwater away).

Question 21

What are the disadvantages Planning & Preparation?

Answer 21

House prices can drop if deemed ‘at risk’ of flooding.

Question 22

What are Wetlands?

Answer 22

land next to a river that is allowed to flood.

Question 23

What are the advantages of Wetlands?

Answer 23

• It stores water so that less water joins the river channel. This prevents flooding.
• Cheap management strategy.
• Creates wetlands which create habitats for animals

Question 24

What are the disadvantages of Wetlands?

Answer 24

Land is flooded.

Question 25

What is River Restoration?

Answer 25

where the river has been changed artificially (e.g. river straightening), river restoration can return it to its original course. It uses the natural processes and landforms of a river (e.g. meanders and wetlands) to reduce the likelihood of flooding.

Question 26

What are the advantages of River Restoration?

Answer 26

• It is environmentally friendly to wildlife and their habitats.
• It is relatively cheap and looks natural.

Question 27

What are the disadvantages of River Restoration?

Answer 27

It is less effective than hard engineering strategies (e.g. river straightening).

Question 28

What are the hard engineering river strategies?

Answer 28

• Dam & Reservoir
• Embankments
• Channel Straightening
• Flood Relief Channels

Question 29

What are the hard engineering river strategies?

Answer 29

• Afforestation
• Floodplain Zoning
• Planning & Preparation
• Wetlands
• River Restoration