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Give four reasons why levees and raised river beds increase flooding

      

Give four reasons why levees and raised river beds increase flooding

  

Answers

Masinde
Levees and raised river beds often prevent costly flood damages and even loss of life. However, when those levees overtop or fail, and water spills onto the floodplain, the long-term damage can be far worse than if those levees were not there.

When rivers are denied the space to meander due to levee and raised river beds, many beneficial river services are diminished. Setback levees increase channel capacity for carrying floodwaters.And Once a levee is setback, the river may begin to meander and this poses a challenge to implementing riparian restoration on the floodplain.

Levees and raised river beds greatly narrow the area available to transport floods, they do work to rapidly flush floodwaters and sediments through the system – but this means that the levees are exposed to high-velocity water along their “wet” side. This can result in erosion.

Levees and raised river beds close to a river also dramatically restrict the area of floodplain that benefits from periodic connections with the river and constricts the ability of the river to meander and create new river- floodplain habitats. Because of the vulnerability to erosion mentioned above, these levees often require armouring to prevent erosion and meandering, further diminishing the natural habitat values of the river’s edge, which is generally the most biologically valuable habitat.And Moving levees back away from the channel often called “setback levees” - can alleviate the flooding problems.
Mr Masinde answered the question on May 1, 2018 at 08:50

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