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River Management - Hard and Soft Engineering - Coggle Diagram
River Management - Hard and Soft Engineering
Hard Engineering (HE) - The construction of physical infrastructure to reduce the risk of flooding - 'building something'.
Soft Engineering (SE) - Working with natural processes to reduce the risk of flooding.
HE - Embankments
Embankments are constructed at the side of the river channel. They increase the bank full capacity and mean that the river can carry more water.
Adv - Effective method, easy to implemenet (no movement of homes out of the way), can be done in almost any location.
Dis - Very expensive method, takes time to build, often uses concrete (very bad for the environment), restrict access to the river, if the river over tops the embankment then they stop the water going back to the river.
HE - Channelisation
This is where a new channel is cut for the river and this is in a straight line. It will speed up the river and allow it to carry more water in the same time
Ad - This means that where the project is undertaken will be safer from flooding
Dis Ad - Causes flooding downstream if no defences (can't cope with faster speed), uses concrete, can't be done everywehre due to land use in the way.
HE - Flood Relief Channels
A new channel is constructed next to the river - if the discharge is high enough - water may be allowed down the relief channel.
Ad - Works well, quite easy to do, means that limited other methods are needed.
Disadvantages - Expensive to build, can't done everywhere as space needed next to the river, need to ensure that the water in the relief channel does not get too high and lead to flooding itself.
HE - Dams and Reservoirs
Dam is constructed which floods an area behind. This means that the water can be controlled down the river.
Adv - very effective (most effecive method), generates hydro-electric power, reservoir can become a tourist attraction and used for recreation.
Dis A - Very expensive (most expensive method), floods an area behind - loss of land, homes, people may need to move, high cost of maintenance, possible risk of collapse with devestating consequeunces.
SE - Washlands
This is where land next to the river is allowed to flood - only done in rural areas.
Adv - Very cheap and works well to alleviate pressure on urban areas.
Dis A - Loss of land, land can't be used for anything else, need to pay farmers to not use the land and for the loss of income.
SE - River Restoration
This is the removal of channelisation - allows the river to meander again.
Adva - Cheap and easy to do. Does not need maintenence.
Disadvantges - Loss of land for farming, river will flood so land use next to the river needs to be considered.
SE - Flood Plain Zoning
Create zones on the flood plain which means that land use can be controlled. Most high risk land has no land use, least risk has houses/businesses.
Advan - Cheap to do and does not need management.
Disadvantages - Can involve moving some buildings out of the way, restricts what can be done with the land.