River Bank Protection Flashcards
Why is bank protection needed
Increasing the rivers velocity via channelisation may also increase its ability to erode which is not ideal. This means some bank protection is needed.
What are the 5 methods of bank protection
Levees
Revetments
River training
Wing dykes (training walls)
Diversion channels
What are levees
Earth mounds raised or created along river banks. Concrete levees are often used in areas of higher land value
Two pros of levees
Increased channel capacity
Reduced flood risk to area and protects surrounding infrastructure
Two cons of levees
Need maintenance
Lead to extreme flooding if levees are breached
What are revetments
Revetments consist of concrete walls, sheet piling, rip rap or gabions
Two pros of revetments
Controls meander migration
Not entire,y artificial
Three cons of revetments
Separates river from floodplain
Loss of Bankside’s habitats
Loss of natural bank profiles
What is river training
Channelisation method to improve navigation or develop and maintain a new channel form. Construction of different structures along a river to guide and confining the river flow in the channel
Two pros of river training
Prevent changing of the river course
Help protects river banks
Two cons of river training
Structures are easily destroyed by river flow
May lead to a high flood level rise
What are wing dykes
Structures built out from the banks towards a centre line of the river to direct the fastest current away from the banks. Used to provide a low water navigable channel
Two pros of wing dykes
Redirects Thales to keep channel clear
Mimics natural processes and landforms
Two cons of wing dykes
Slower velocity and visual pollution
May not actually help navigation
What are diversion channels/spillways
A second overflow channel constructed to take the additional floodwater. Diversion channels run parallel to the existing river, rejoining it downstream of the section being protected
