After a long period of rain, the soil becomes saturated. Any further rainfall can't infiltrate, which increases run off into rivers. This increases discharge quickly, which can cause a flood.
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Physical factors heavy rainfall
Heavy rainfall means there's a lot of runoff. This increases discharge quickly which can cause a flood.
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Physical factors snowmelt
When a lot of snow or ice melts it means that a lot of water goes into the river in a short space of time. This increases discharge quickly, which can cause a flood.
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Physical factors geology
When a river is in an area of impermeable rock water doesn't percolate onto the rock, but flows on the surface. Thiis means there's more runoff, so the risk of flooding is higher.
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Human factors deforestation
Trees intercept rainwater on their leaves, which then evaporates. Trees also take up water from the ground and store it. This means cutting down trees increases the volume that reaches the river channel, which increases discharge flooding is likely.
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Human factors building construction
Buildings are made of impermeable materials. Impermeable surfaces increase runoff and drains quickly take run off to rivers. This increases discharge quickly, which can cause a flood.
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Other cards in this set
Card 2
Front
Physical factors heavy rainfall
Back
Heavy rainfall means there's a lot of runoff. This increases discharge quickly which can cause a flood.
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