Tidal Flooding

Coastal flooding

Graphis produced by the Natural Environment Research Council to illustrate the causes of tidal (or coastal) flooding. Copyright: NERC, Ben Gilliand.

The risk of tidal flooding comes from the overtopping of sea defences that separate the land from the estuary. These are designed to cope with normal tidal cycles, but also with unusual water levels. The standard of a defence is determined by the likelihood of an event occurring which could overtop it. For example, the Hull Tidal Barrier is built to withstand up to and including a 1 in 200 year storm – this means there is statistically a 0.5 % chance of it overtopping in a year.

The raised water levels which cause tidal flooding are most often caused by storms. These low pressure systems, helped by strong winds, raise up the levels of the sea – this is called a storm surge. When these surges coincide with a high tide there’s a possibility they might overtop the defences.

The Met Office has a very useful page with more information on storm surges, here.

Although we hope you enjoy using Humber in a Box, its real purpose is to raise awareness of the risk of tidal flooding, and to direct you to the useful information that will help you plan for any possible flooding.


Please visit the Flood Aware website, here. Or, call the floodline on 0345 988 1188

The Environment Agency is actively working to reduce the current flood risk around the Humber Estuary and to improve the defences going into the future. This includes planning for future sea level rises.

The current Humber Flood Risk Management Strategy can be viewed here.


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