Tuesday, October 29, 2013

Natural resources-Floods

A flood is an overflow of water, whenever the magnitude of flow of waterexceeds the carrying capacity of the channel within its banks.

  1. Heavy rainfall, melting of snow (ice), sudden release of water from dams often causes floods in the low lying coastal area.
  2. Prolonged heavy rainfall can also cause the overflowing of lakes and rivers resulting in floods
  3. Reduction in carrying capacity of river channels due to accumulation of sediments or obstructions built on flood ways.
  4. Deforestation, overgrazing, mining increases the run-off from rains causing floods.
  5. Removal of dense and uniform forest cover over the hilly zones leaqds to occourrence of floods.
Due to floods:
  1. Water spreads in the surrounding areas and submerges them
  2. Plain surfaces get eroded and silted with mud and sand thereby affecting cultivable land areas.
  3. Extinction of civilization in some coastal areas also occurs.
  1. Floods can be controlled by constructing dams or reservoirs
  2. Channel management and embankments also control floods
  3. Encroachment of flood ways should be banned
  4. Flood hazard may be reduced by forecasting or flood warning
  5. Flood hazard may be reduced by reduction of runoff and this can be achieved by increasing infiltration through appropriate afforestation in the catchment area.

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