How well do flood defence models match reality?

Sometimes flood defence embankments can fail, or breach, when river or sea levels rise during a flood. These are rare but potentially damaging events. They are included in the Environment Agency’s national flood risk assessment models, and so we are interested to know how the models compare with what has happened in real floods.

In the summer of 2013 we worked with Janie Haven who was studying for her MSc in Water and Environmental Management at the University of Bristol.

The research described here is based on Janie’s work for her dissertation “A Comparison of Actual Fluvial Embankment Flood Defence Performance to RASP Estimated Performance”, completed with the support of the JBA Trust, Horritt Consulting and the Environment Agency.

Click here for a summary of the research results

The research found that

  • The flood risk models suggested that we should have been seeing more flood defence failures then actually seem to have been observed
  • Sensitivity analysis showed that substantially more flood defence failures would be expected if these assets were in a worse condition

The findings of our study support on-going initiatives to collect better, more consistent records on flood defences, including breaches, and to update flood risk models.