Physical and Human Causes of River Floods

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  • Causes of River Flooding
    • Physical
      • Drainage Density
        • high drainage density means water reaches channel quickly
          • speeds up transfer of water making flooding more likely
      • Long Profile
        • steep upper course + flat lower course
          • rapid transfer to low ground where water transfer slows
            • build up of water might cause flooding
      • Snow Melt
        • form a store of water
          • when melts store is rapidly released
            • if ground is still frozen overland flow will occur and go into rivers quickly
      • Steep Slopes
        • mountainous area rapid overland and through flow
      • Rock Type
        • Impermeable rock encourages overland flow
          • rapid water transfer to river channel
      • Intense/Prolonged Rainfall
        • intense rain fall (e.g. tropical storms + monsoons) cause significant floods
        • prolonged rainfall lead to river flood in early spring
    • Human
      • Agriculture
        • arable farming
          • areas left exposed
            • lead to extra surface runoff
      • Deforestation
        • trees shelter the ground
          • therefore removing trees means water can be transferred to channels quickly increasing risk of flood
        • water that normally falls on leaves is then evaporated  /stored temporarily
          • therefore removing trees means water can be transferred to channels quickly increasing risk of flood
        • trees also use water up fro the ground when they grow
        • Flood Management + Warning System
          • lack of appropriate flood defences and schemes or poor warning systems increase risk to people
          • if flood defences are not repaired or upgraded floods are more likely
          • badly maintained underground channels or bridges lead to blockages and flooding
        • Building and construction
          • building on floodplain creates an impermeable surface
            • transfers water quickly to channel causing them to fill quickly and over flow

    Comments

    Mr A Gibson

    A nice breakdown into human and physical causes of flooding - get this up on your wall!

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