Flooding, flood sources and flood defences

The EU Flood Directive defines “flood” as the temporary covering by water of land not normally covered by water. This shall include floods from rivers, mountain torrents, Mediterranean ephemeral water courses, and floods from the sea in coastal areas, and may exclude floods from sewerage systems. The exclusion of floods from sewerage systems is concerned with operational or managerial failures, often in dry weather, but sewer flooding caused by rainfall is not excluded. “Flood risk” is defined in the directive as the combination of the probability of a flood event and of the potential adverse consequences for human health, the environment, cultural heritage and economic activity associated with a flood event. The definition of “flood” within the Directive does not distinguish between the physical processes that have shaped the natural world around us and those which occur as a result of human kind’s interaction with water. The reality is that “flood risk” is seldom a natural problem and it is almost entirely caused by the decisions of people in their relationship with water.