Flood events are referred to in terms of their Annual Exceedance Probability (AEP). The AEP is a measure of the likelihood that a flood of a given magnitude will occur once or more within any given year. The AEP is expressed as either a “one in X” value (e.g. 1:200) or as a percentage (e.g. 1:200 equates to 0.5%).
The table below summarises the return periods discussed in this report, and the equivalent AEP of these events.