鶹Լ

Human management of rivers - EdexcelCase study - flooding in Cumbria, October 2021

Hard engineering management involves using artificial structures, such as dams and embankments. Soft engineering management is a more natural approach to manage flooding, such as floodplain zoning.

Part of GeographyChanging UK landscapes

Case study - flooding in Cumbria, October 2021

Cumbria is in North West England. It is the third largest English county by area and is largely rural. The River Derwent runs north and then west through part of the county.

Physical processes that impact flooding

Cumbria is one of the wettest places in the UK. The county is exposed to air masses from the Atlantic Ocean, which bring high levels of precipitation. In October 2021, a slow-moving weather system caused unusually heavy rainfall across many parts of the UK. Cumbria experienced widespread flooding. More than a month’s worth of rain (12in or 30cm) fell within a 24-hour period.

Much of Cumbria is hilly or mountainous. This can lead to flooding in two ways:

  • As air rises over high land, it cools and condenses into clouds and rain. The higher parts of the county are therefore the wettest. Some places receive more than 3200mm of rain each year.
  • Water runs off steep slopes more quickly.

Many of the rocks beneath Cumbria are impermeable. This means that they do not allow water to soak into them. Instead, rainfall is more likely to be stored in the soil and on the surface of the ground.

Human processes that impact flooding

There are increasing numbers of new homes being built in Cumbria. Some of these are on greenfield sites. Housing developments can increase problems of flooding as they have many impermeable surfaces which stops water from soaking into the ground.

Deforestation takes place in some parts of the county. Trees help to prevent flooding by intercepting and absorbing rainwater. Fewer trees means that more water enters rivers and streams.

Severe flooding took place in Cumbria in 2015. Around 50,000 homes were affected, causing damage estimated to cost £500 million. After 2015, the council spent £2.6 billion on flood defence schemes to protect the region from future flooding. In October 2021, only 43 properties were flooded. Over 1400 properties were thought to have been protected by the new flood defences.