Accounting for residual uncertainty: an update to the fluvial freeboard guide

This new research will help flood risk managers identify and manage uncertainty in their flood risk assessment and designs.

Documents

Accounting for residual uncertainty: an update to the fluvial freeboard guide - summary (354KB) PDF

Accounting for residual uncertainty: an update to the fluvial freeboard guide - technical report (3.2MB) PDF

External link: Accounting for residual uncertainty: an update to the fluvial freeboard guide - webinar

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Details

The Environment Agency (EA) has published a new research report that will help flood risk managers identify and manage the uncertainty in their flood risk assessments and flood defence designs. This new guide is written for all flood risk management authorities, developers, and engineering consultants who work on their behalf.

Current advice on the use of this guide is:

  • EA and National Resources Wales (NRW) capital projects that have already calculated a freeboard allowance using old guidance (W187), and which are due to deliver outcome measures by March 2021, do not need to revise their cases to account for this new guide.
  • All other capital projects should use the Residual Uncertainty Allowances approach.
  • Developers should submit flood risk assessments to EA/NRW in accordance with local advice until advised to do otherwise.
Published 24 February 2021