IGCSE flooding

What causes river flooding?

When the amount of water moving down a river exceeds the capacity of the river’s channel

How does geology cause flooding?

Flooding is much more likely in places where the rock or soil are less permeable because water can’t get into the ground but has to flow over it and into rivers making them rise

How does relief cause flooding?

The height and slope of the land can mean rain runs off more easily

How do weather events cause flooding?

Heavy rain may be too fast for infiltration to happen and so it leads to surface runoff

How does forestry cause flooding?

Felling trees stops them from absorbing water through roots and stops interception. If there are no roots less water can enter the ground as roots are good at breaking up the soil

How does monsoon rain cause flooding?

In Asia heavy rains fall in the monsoon causing large scale flooding as there is so much water in a short time that it can’t infiltrate

How does snow melt cause flooding?

Sudden snow melt causes a release of stored water and a rise in river level

How does urbanisation cause flooding?

New housing, pavements and car parks are being built with impermeable surfaces and so rain cannot infiltrate into the ground but runs off into rivers making them rise and flood

What does hard engineering flood management mean?

Uses heavy machinery to build artificial structures which work against nature to reduce the risk of flooding

What does soft engineering flood management mean?

Adapts to a river and learns to live with it. These strategies are cheaper but can be less effective