Rivers 3- Flooding Flashcards
Flood frequency-magnitude analysis
The study of how often dangerous high discharge floods usually occur, so we can attempt to predict the likelihood of similar floods in the future
The Environment Agency
A branch of the government that works on protecting settlements from a flood likely to recur once every hundred years
Physical causes of flooding
Excessive & prolonged rainfall, intense rainfall, snow melt, coastal storm surges
Human causes of flooding
Urbanisation, deforestation, climate change, farming, hard engineering
Hard engineering
Modification to the channel or floodplain to protect settlements
Expensive, effective but unsustainable
Soft engineering
Ways of slowing down the rate of water entering the river or reducing the amount of water that actually reaches the channel
Artificial embankments
Artificially raised and strengthened banks to increase the river channel volume
Channelisation
Channels artificially straightened and lined with concrete
Increases velocity but puts areas downstream at greater risk
Channel enlargement
Involves dredging (deepening) and removal of boulders from the channel Similar effects to channelisation
Flood relief channels
Redirects water (excess water) around a settlement
Flood storage reservoirs/balancing lakes
Storing excess water in a lake
Dams
Blocks the flow of water and stores it in a reservoir
Causes siltation and affects wildlife
Afforestation
Planting trees to increase interception
A long term strategy
Agricultural land use management
Contour ploughing, strip farming and crop stubble to prevent soil erosion and increase interception/infiltration
Land-use zoning
Using the floodplain area for recreational or grazing activity so it is allowed to flood
