River flooding defences Flashcards
Hard engineering river defences
dams and reservoirs, channel straightening, embankments, flood relief channels
Soft engineering river defences
flood warnings, preparation, flood plain zoning, planting trees, river restoration
Dams and reservoirs definition, benefits, losses
huge walls built across river in the upper course a reservoir is formed behind the dam. Reservoir store water especially in heavy rain, can be used as drinking water or HEP. Very expensive, eroded material is deposited in the reservoir causing the river to be less fertile
Channel straightening definition, benefits, losses
rivers meanders are cut out by having straight channels. Water moves out of the area faster as it doesn’t travel as far. Flooding may happen downstream, more erosion downstream as water is flowing faster
Embankments definition, benefits, losses
raised walls are built along the river banks. Can hold more water so it will flood less frequent. Expensive, risk of serve flood if the water rises above the embankments ro if they break
Flood relief channels definition, benefits, losses
channels are built to divert the water around important areas or take it elsewhere if water level is too high. River discharge is reduced. Gates on the flood relief channel mean the release of water can be controlled
Flood warnings definition, benefits, losses
warning about possible flooding. Impact of flooding is reduced, possessions can be moved and action can be made. Don’t stop the flood, people could miss the warnings
Preperation definition, benefits, losses
buildings are modified to reduce the amount of damage, people make plans of what to do. Impact of flooding is reduced, less damage and people know what to do. Doesn’t guarantee safety, false sense of security, expensive to modify homes
Flood plain zoning definition, benefits, losses
restrictions prevent building on parts of a flood plain that are likely to be affected by a flood. Risk of flooding is reduced as impermeable surfaces aren’t created, impact of flooding is reduced. Expansion of urban area is limited, no help to already built areas
Planting trees definition, benefits, losses for flooding
increases interception and lag time. Flood risk is reduced, vegetation decreases soil erosion and provides habitats. Less land for farming
River restoration definition, benefits, losses
making the river more natural, removing man made things. Less risk of flooding, less maintenance, habitats. Local flood risk can increases if nothing is done to prevent major flooding
