Flash Flood Risk
What is Flash Flooding?
Flash floods occur extremely quickly and with massive force. They can move rocks, tear out trees, sweep away vehicles and destroy buildings and bridges.
Flash flooding is often associated with surface water rising when drains are unable to cope with heavy rainfall. Flash flooding may also occur from watercourses which are very responsive to heavy rainfall, meaning river levels rise quickly.
These watercourses are within drainage areas called ‘Rapid Response Catchments’. The extremely quick response to heavy rainfall is often due to steep valley slopes and urban areas in these catchments, where water runs off the land straight into the river.
Across England, the Environment Agency have identified 384 ‘Rapid Response Catchments’, with over 75,000 properties being identified as being vulnerable to this risk. There are 16 Environment Agency classified Rapid Response Catchments in Cornwall, that are shown on the map below as blue markers. Click on a marker to view communities at risk from flash flooding.