EQ5 -4.8

Question 1

Compare how soft and hard engineering schemes work

Answer 1

Hard engineering

Man-made structured built to control the flow of rivers and reduce flooding

Soft engineering

Schemes set up using knowledge of a river and its processes to reduce the effects of floodong

Question 2

Flood walls

Answer 2

A high wall alongside a river to increase its capacity to prevents flooding. Fairly cheep, once built, its done.

Pros
Useful for city centres where space is limited

Cons
Dispense water quickly snd can increase flood risk downstream

Depends on type of wall and material used

Question 3

Levees (embankments)

Answer 3

Increases capacity of river. Usually built at a distance from the river increasing capacity even more

Pros
Expensive but allows people to live beside river or farm with reduced fear of flooding

Cons
Can increase flood risk downstream

Levees can fail by overtopping (water rises over), slumping or erosion

Question 4

Dredging & flood relief channel

Answer 4

Dredging increases river capacity, or line river with concrete to speed river flow to get water away quickly

Pros
Expensive but cheap to maintain concrete lining

Cons
£50,000

Dredging needs to be done every year as sediment fills up when it rains heavily

Speeding up flow increases flood risk downstream

Question 5

Flood plain retention

Answer 5

Level of flood plains is lowered. Surfaces restored to vegetation so they can retain water over a period and slowly release into the river

Pros
Increased ability to store flood water

Cons
£1.2m for 2km stretch

Question 6

River channel restoration

Answer 6

Some meanders were rebuilt lengthening the river and slowing water down. Concrete and hard engineering materials were replaced with sediment and planted with trees

Pros
Improved ecology with 30% in birds and insects within one year

People like the more natural look in a survey of 82% people liked it ‘mostly or strongly

Question 7

Afforestation

Answer 7

Planting trees in the upper course of the river intercepts large volumes of water and allows for more evapotranspiration. Surface runoff is reduced as a result and the flood risk is reduced

Pros
Natural way of reducing flood risk which improves the view in an area. It increases natural habitats for wildlife. There is low maintenance required

Cons
Trees (if bought largely grown) are expensive and if they are saplings (young) they take a long time before they are effective