Delivering benefits through evidence: accounting for residual uncertainty - an update to the fluvial freeboard guide

The Environment Agency has developed a new guide that will help flood risk managers identify and manage the uncertainty in their flood risk assessments and flood defence designs.

This new guide replaces the Environment Agency’s Fluvial Freeboard Guidance Note (report W187) published in 2000. It is written for all flood risk management authorities, developers, and engineering consultants who work on their behalf.

The guide supports flood risk management as it:

• Provides a structured method for identifying uncertainties across the flooding system;
• Ensures that any factors of safety used in the design process are not duplicated;
• Helps users consider all appropriate actions for managing uncertainty across the source pathway and the receptor;
• Ensures uncertainties are identified, managed and tracked as a project moves from the strategic case through the appraisal process to design and delivery;
• Provides a hierarchy of methods to ensure the management of uncertainty is proportional to the decision.