Hard vs Soft engineering Flashcards
(26 cards)
name the four types of hard engineering?
Dams and reservoirs
channel straightening
embankments
flood relief channels
What are the benefits of dams and reservoirs?
store water, control water flow and prevent floods downstream
they can also be used to generate hydroelectric power
what are dams and reservoirs?
dams - barriers built across the river, usually in the upper coarse
reservoirs - (artificial lake) built behind dams
what are the disadvantages of damns and reservoirs?
very expensive to built
creating reservoirs can flood existing settlements
material is deposited in the reservoirs, not along the course, so farmland downstream can become less fertile.
what is channel straightening?
meanders are removed by building straighter artificial channels
what are the benefits of channel straightening?
water leaves the area more quickly rather than building up, so flood risk is lower.
what are the disadvantages of channel straightening?
flooding may happen downstream instead
Faster-moving water may cause more erosion downstream
What is Embankments?
raised walls are built along river banks
what are the benefits of embankments?
the river can hold more water so floods are less frequent.
what are the disadvantages of Embankments?
They’re quite expensive and there is a risk of severe flooding if the water rises above the levels of the embankments or if they break.
what are flood relief channels?
channels are built to divert water around built-up areas or to divert excess water if the river level gets too high.
what are the benefits of flood relief channels?
gates on the channels mean the release of water can be controlled reducing flood risk.
what are the disadvantages of flood relief channels?
there will be increased discharge where the relief channel rejoins the river ( or joins another river) which could cause flooding.
what are the 4 types of soft Engineering?
flood warnings and preparation
flood plain zonning
planting trees
river restoration
what are flood warnings and preparation?
The environment agency issues flood warnings through various media
buildings are modified to minimise flood damage
residents can prepare sandbags and flood boards prior to floods
what are the benefits of flood warnings and preparation?
warnings give people time to move possessions upstairs, put sandbags in place or evacuate. this reduces the impact of flooding
what are the disadvantages of flood warnings and preparation?
warnings don’t prevent floods. people may not have access to warnings.
modifying buildings is expensive
preparation doesn’t guarantee safety from a flood and it could give people a false sense of security.
what is flood plain zoning?
restrictions prevent buildings on parts of a flood plain that are likely to be affected by a flood.
what are the benefits of flood plain zoning?
flood risk is reduced - fewer impermeable surfaces are created like roads,
the impact of flooding is also reduced- there are no buildings to damage
what are the disadvantages of flood plain zoning?
the expansion of Urban area is limited if there aren’t any other suitable building sites,
it cant help in areas with existing builds.
what is planting trees?
planting trees in the river valley increases the interception of rainwater
what are the benefits of planting trees?
discharge and flood risk decrease.
vegetation reduces soil erosion in the valley and provides habitats for wildlife.
what are the disadvantages of planting trees?
less land is available for farming.
what is river restoration?
making the river more natural e.g. by removing man-made levees so that the plain can flood naturally.
