Design flood

A flood of known magnitude or average recurrence interval, or a historic event which is selected for land use planning, emergency planning and engineering design purposes. The selection should be based on the understanding of flood behaviour and associated flood risk. It should also take into account the social, economic and ecological consequences associated with floods of different severities. Note that the design flood does not define the maximum extent of land liable to flooding, which is defined by the Probable Maximum Flood (PMF).