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River Management 2011

methods of management
by

leong leong

on 23 July 2011

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Transcript of River Management 2011

RIVER MANAGEMENT process of planned human intervention in the course, characteristics or flow of a river with the intention of producing some defined benefit. Why river management? flood shifting course aid navigation damage natural
habitats damage human lives infrastructure properties land & crops Prevent Control utilise river resource water storage dams irrigation HEP Methods to achieve the 3 benefits: Prevent, Control, Utilise Benefits? Soft Engineering Hard Engineering Planting Vegetation re-sectioning re-alignment bank protection Habitat Enhancement Program
allowing continued private recreational access
providing meaningful habitat creation, enhancement
protection activities for fish and wildlife re re-sectioning is the widening and deepening of the river channel Advantage of this method
widens and deepening the river channel
increases the ability to hold water
increases the amount of surface runoff from the surrounding areas to the river
more surface runoff can now enter the river without causing flood
can be smoothened by replacing soil to cement and granite
less friction and therefore speed of the water in the river increases Disadvantage of this method
still cause flooding downstream
rivers can bend back into a meander and affect the habitats of animals and plants Re-alignment is the straightening of the river channel Advantage of this method
Straightening of river channel
Deepens the channel, allowing it to hold more water
Removes meanders and reduce the length of the river
Increase the flow of the speed
Water flows very quickly and washes away sediments Bank Protection is to prevent flood & reduce soil erosion Artificial levees or dyes (Advantage):
• Increases the capacity of the river to hold water
Negative:
• Continual build up of sediments on the river bed which make the channel narrower
• Cause water levels to rise higher than the dyke walls
Gabions and revetments:
• Divert flow of water from river banks to centre of the river
• Protects the river banks from erosion
• Reducing the amount of sediments in the river
• Less sediments = more capacity to hold water Disadvantage of this method ? Still cause flooding downstream if sediments collected are significant
River banks can still overflow Planting vegetation along the river to prevent it against erosion Advantage of this method:
protect river banks against erosion
slows down the rate of surface run off
prevents large amount of water from entering the river
reduce the amount of eroded sendiments Disadvantage of this method:
Still cause flooding downstream
Too much shade will affect aquatic plants and may kill them. This will affect the biological food cycle if they are part of the food chain Can you state the common advantages/disadvantages among these 4 methods ?
Which method do you think is the most effective in river management ? You may use up to more than one method as long as it is being justified.
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