Causes of flooding

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  • Created on: 02-06-13 15:02
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CAUSES OF FLOODING
River level increases when the discharge increases. Factors that increase
discharge can cause flooding
Prolonged rainfall: After a long period of rain the soil becomes
saturated. Any further rainfall can't infiltrate, which increases runoff
into rivers. This increases discharge quickly, which can cause a flood.
Heavy Rainfall: Heavy rainfall means there's a lot of runoff. This
increases discharge quickly, which can cause a flood.
Snowmelt: When a lot of snow or ice melts it means that a lot of water
goes into a river in a short space of time. This increases discharge
quickly, which can cause a flood.
Relief: If a river is in a steep-sided valley, water will reach the river
channel much faster because water flows more quickly on a steeper
slope. This increases discharge quickly, which can cause a flood.
Rivers can also flood because of 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 of water that reaches
the river channel, which increases discarge and makes flooding more
likely.
Building contstruction: Buildings are often made from impermeable
materials e.g concrete, and they're surrounded by roads made of
tarmac. Impermeable surfaces increase runoff and drains quickly take
runoff to rivers. This increases discharge quickly, which can cause a
flood.

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