Causes of Flooding Flashcards
Three ways humans can increase the risk of flooding in rural areas are:
- Deforestation
- Intensive farming, leaving fields bare in the winter
- Overgrazing
- Increased use of polytunnels
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Building a new housing estate on the floodplain increases the risk of flooding because the surface becomes impermeable due to the construction of houses, tarmac roads and concrete pavements. Surface run-off increases leading to a rapid increase in a river’s discharge.
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Three ways humans can increase the risk of flooding in urban areas are:
- Building new infrastructure e.g. roads and paths
- Building new houses
- Disappearing gardens
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A change from pastoral to arable farming increases the risk of flooding because once crops have been harvested the soil is sometimes left bare in the winter. This reduces interception because there is no vegetation.
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Relief can increase flood risk because:
- Steep sided slopes mean that it is hard for infiltration to occur which leads to greater surface run-off
- Low lying flood plains are at risk of flooding because they do not have enough gradient to move the water on quick enough. This risk increases when the soils have a high clay content.
- Upland areas are more likely to experience rain due to relief rainfall. This increases the likelihood of high levels of precipitation and therefore surface run-off.
Find out more about human and physical causes of flooding.