Building artificial levees has been said to be self-perpetuating. ...

[hubes95]

Building artificial levees has been said to be self-perpetuating. Why does building a levee in one place
  along a river system prompt the construction of another downstream? What will be an ideal response?

Question 2

What are two benefits and two negative aspects of large dams on rivers? What will be an ideal response?

[polinasid]

Answer to Question 1

Where new levees are built, usually on top of natural ones, floodwater is prevented from entering the
adjacent floodplain. This water is then forced to flow downstream to other areas. Natural levees in
those areas will then experience higher than normal water levels and may be overtopped. The typical
solution to this flooding problem is construction of an artificial levee. During the next high water
period, the story is repeated, thus perpetuating levee construction in the downstream direction.

Answer to Question 2

The benefits could include cheap electricity, clean electricity, flood control, irrigation, recreation, and
drought prevention. The negative aspects could include loss of habitats, endangerment of species, loss
of natural flooding, sediment deposition, increased erosion below the dam, negative effects to delta
areas downstream, and in some cases, loss of life from failure of dams.

[hubes95]

TY

[polinasid]

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