Causes of Flooding

Human and physical causes of flooding.

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  • Causes of Flooding
    • Physical Factors.
      • Prolonged rainfall.
        • The soil becomes saturated after a long period of rain. Then any more rain can't infiltrate through the soil which increases surface runoff into rivers. This increases the discharge quickly which can cause a flood.
      • Heavy rainfall.
        • Heavy rainfall means there will be a lot of run off. This increases discharge quickly which can cause a flood.
      • Snowmelt.
        • When lots of snow or ice melts lots of water goes into a river in a short space of time. This increases discharge quickly, which can cause a flood.
      • Relief (how height of land changes).
        • If the river is in a steep valley, then the water will reach the river faster because water flows quicker on steeper slopes. This increases discharge quickly which can cause a flood.
    • Discharge = the volume of water that flows in a river per second.
    • Human Factors.
      • Deforestation.
        • Trees get rainfall on their leaves, which then evaporates. Trees also take water from the ground and store it. Therefore cutting down trees increases amount of water that reaches the channel, which increases the discharge and makes flooding more likely.
      • Building construction.
        • Builds are often made from impermeable materials (concrete), and they are surrounded by roads (tarmac) which are impermeable. Impermeable surfaces increase runoff and drains take runoff to rivers quickly. This increases discharge quickly, which can cause a flood.

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