Contents of the Strategic Flood Map

The Strategic Flood Map illustrates areas throughout Northern Ireland that are estimated to be prone to flooding from rivers and the sea. It also provides additional information on the location of raised flood defences (such as embankments and walls) and shows the areas which benefit from a reduction in the likelihood of flooding as a consequence of their presence.  

At present the Strategic Flood Map does not show areas that are prone to flooding from other significant sources such as overflowing sewerage or drainage systems or Pluvial flow.  Pluvial flow is rainfall-generated overland flow that can fill low lying areas and hollows before reaching a watercourse or sewer.  When appropriate, the existing map layers shall be reviewed and updated as new information becomes available.

Users should note that flood information is not available for every river in Northern Ireland as there are many small rivers and sections of small rivers for which sufficient data was not readily available to enable hydraulic modelling to be undertaken.  These ‘un-modelled’ rivers, which typically have a catchment area of less than three square kilometres, are identified within the Present Day and Climate Change flood maps by the use of a dashed blue line.  The rivers which have been ‘modelled’ for this strategic flood assessment are highlighted with a solid blue line within these maps.  Detailed information on the current map layers that are contained within the Strategic Flood Map is given below under the relevant headings.