Flood risk explained

A "one-in-100" year flood is often misinterpreted as a flood that strikes once per century. The measurement actually refers to how likely it is that a flood of certain scale will occur in any given year. In the example below, the 1 in 100 year flood level at Windsor is 17.3 metres. That means there's a 1 per cent chance a flood of that magnitude will occur each year.