flood engineering

Question 1

what are dams and reservoirs?

Answer 1

• dam: concrete barrier built across a river channel
• reservoir: artificial lake behind the dam
• river discharge is released from the reservoir in a controlled way, reducing the flood risk

Question 2

what are the advantages and disadvantages of dams and reservoirs?

Answer 2

a:
- hydroelectric power can be generated as water is released
- tourism to reservoirs is popular

d:
- expensive to build
- floods settlements and land

Question 3

describe the process of channel straightening:

Answer 3

• meanders removed, makes the channel wider, deeper and straighter
• allows river discharge to flow away from the area more quickly, reducing the risk of a flood

Question 4

what are the advantages and disadvantages of channel straightening?

Answer 4

a:
- new habitats can be created to make the channel look more natural
- reduction in insurance costs for nearby houses and businesses
- improved navigation (e.g. boats)

d:
- flooding and erosion may still occur downstream
- can be expensive (the river valency in cornwall was part of a £10 million management plan)
- damage to habitats in order to create the channel

Question 5

what are embankments?

Answer 5

• artificially raised river banks
• deepen the channel, so that the capacity of the river increases, reducing flood risk

Question 6

what are the advantages and disadvantages of embankments?

Answer 6

a:
- foot and cycle paths can be created
- cheaper to put in place, compared to other options
- some embankments have added vegetation, increasing number of local habitats

d:
- high maintenance costs
- can be seen as unattractive (may affect tourism?)
- risk of more of a severe flooding if the embankments are breached

Question 7

what are flood relief channels?

Answer 7

• artificial channels which divert river discharge away from high risk areas
• prevents excess river discharge during periods of high rainfall, to prevent the river from reaching its bank full capacity and flooding

Question 8

what are the advantages and disadvantages of flood relief channels?

Answer 8

a:
- gates on the channels allow controlled release of discharge
- lowers insurance costs and property protection

d:
- when discharge is released, it could cause a flood
- incredibly expensive to build and maintain
- takes up land to build, and can look unattractive at low level

Question 9

how does soft engineering differ from hard engineering?

Answer 9

soft engineering is cheaper, better for the environment and easier to maintain, but it isn’t as effective.

Question 10

describe flood warning and preparation:

Answer 10

• the environment agency issues flood warnings, based on weather data
• these will be issued on the media e.g. the news
• this’ll give people time to prepare and make prior modifications to buildings
• action plans can also be drawn up prior to a flood

(TO PREPARE: move possessions upstairs, add sandbags or floorboards to properties, evacuate elsewhere)

Question 11

what are the advantages and disadvantages of flood warning preparation?

Answer 11

a:
- gives people time to prepare, reducing overall effects of the flood
- low cost
- makes people feel secure and in control

d:
- doesn’t actually prevent the flood, leaving homes and businesses at risk
- people don’t always act on warnings
- not everyone has access to the internet to receive these warnings

Question 12

describe floodplain zoning:

Answer 12

• where the land use in a river valley is planned carefully to reduce the effects of flooding
• high value properties and land use are placed further away from the channel

Question 13

what are the advantages and disadvantages of floodplain zoning?

Answer 13

a:
- risk of a flood is reduced because there are less impermeable surfaces in the immediate vicinity of the river, meaning rainwater will enter the river more slowly
- an increase in green space
- less damage/loss of life when a flood occurs

d:
- many urban areas have already built on ‘at risk’ zones. it would be difficult to change this
- there is a housing shortage in the uk - not being able to build on certain areas will add to it

Question 14

describe the strategy of planting trees:

Answer 14

• trees intercept rainfall
• they also undertake transpiration, and they store water
• if we plant more trees, less rainwater will reach the channel
• this reduces the chance of the river reaching bank full capacity and flooding

Question 15

what are the advantages and disadvantages of planting trees?

Answer 15

a:
- increase in natural habitats
- trees absorb carbon dioxide, mitigating climate change

d:
- less farmland will be available as trees will be planted on valuable land
- trees take time to grow so the impact of the strategy might be delayed
- less land is available for building homes and businesses

Question 16

describe river restoration:

Answer 16

• restoring a river channel back to its original state, having been managed by hard engineering in the past
• allows the floodplain to flood more naturally
• reduces flooding downstream, which may have been created due to channel straightening

Question 17

what are the advantages and disadvantages of river restoration?

Answer 17

a:
- requires less maintenance, reducing costs
- new habitats are created, with increased biodiversity
- tourism to the area may increase, creating jobs and increasing income

d:
- restoring a river can be very expensive
- may be an increase in localised flooding, putting some properties at risk
- may be a loss of agricultural land as the river naturally meanders