Question

Ironically, the dams that were constructed to control floods have triggered floods due to _____.

• A. Poor construction
• B. Sedimentation in the reservoirs
• C. Submergence of land
• D. Mechanical failures

Answer 1

The correct option is B Sedimentation in the reservoirs

• A dam is a man-made structure built across a river.
• Most dams are built to control river flow, improve navigation, and regulate flooding.
  
• Dams are made from earth, rocks or concrete and are usually constructed on rivers to store the water in a reservoir.
  
• All rivers contain sediments: a river, in fact,can be considered a body of flowing sediments .
• When a river is stilled behind a dam, the sediments it contains sink to the bottom of the reservoir.
  
• The amount of sediment carried into a reservoir is at its highest during floods .
  
• The construction of a dam blocks the flow of sediment downstream, and increased sediment build-up in the reservoir.
  
• This triggers floods,