flood engineering Flashcards
what are dams and reservoirs?
- 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
what are the advantages and disadvantages of dams and reservoirs?
a:
- hydroelectric power can be generated as water is released
- tourism to reservoirs is popular
d:
- expensive to build
- floods settlements and land
describe the process of channel straightening:
- 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
what are the advantages and disadvantages of channel straightening?
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
what are embankments?
- artificially raised river banks
- deepen the channel, so that the capacity of the river increases, reducing flood risk
what are the advantages and disadvantages of embankments?
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
what are flood relief channels?
- 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
what are the advantages and disadvantages of flood relief channels?
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
how does soft engineering differ from hard engineering?
soft engineering is cheaper, better for the environment and easier to maintain, but it isn’t as effective.
describe flood warning and preparation:
- 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)
what are the advantages and disadvantages of flood warning preparation?
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
describe floodplain zoning:
- 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
what are the advantages and disadvantages of floodplain zoning?
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
describe the strategy of planting trees:
- 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
what are the advantages and disadvantages of planting trees?
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
