Causes of river flooding

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  • Created by: Annis
  • Created on: 27-02-14 18:48
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  • Causes of river flooding
    • Physical (Natural)
      • Prolonged rainfall
        • Lots of rain causes soil to become saturated, so further rainfall cannot infiltrate (be absorbed)
          • This increases surface run off into the river
            • This means there is a fast discharge increase in the river
      • Snowmelt
        • When snow melts lots of water is released quickly
          • This causes a fast increase in river discharge
      • Land relief (gradient)
        • In a steep sided valley the water will flow down to the river much quicker
          • This increases river discharge
      • The geology of the area
        • If the rocks in the surrounding area are impermeable water cannot infiltrate
          • This increases the surface run off
            • And causes a fast increase in discharge
    • Human
      • Deforestation
        • Trees are cut down
          • They cannot intercept rainfall
          • They cannot store/drink water with their roots
            • This means the volume of water reaching the river is increased
              • They cannot intercept rainfall
          • This also means there is nothing holding the soil together
            • The soil is eroded and washes into the river
              • This raises the riverbed and decreases the amount of water the river can hold.
      • Urbanisation
        • Buildings/roads made of impermeable materials
          • Water cannot infiltrate/percolate
            • High surface run off
        • Drainage systems
          • Water cannot infiltrate/percolate
            • High surface run off



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