Sea (Coastal) Flood Map

The Sea Flood Map provides an illustration of the coastal flood plains which are the relatively flat areas of land around the shoreline that are subject to periodic coverage by the sea. The outlines of the floodplains highlighted in the map identify the areas that in any year have a 1 in 200 or greater chance (0.5% Annual Exceedance Probability (AEP)) of flooding from the sea. This map layer has been developed using a computerised coastal model that simulates how extreme tides combine with storm surges and onshore waves to produce high water levels at 48 locations around the coastlines. As the model is strategic in nature the flow characteristics of the inundation during a tidal cycle were not taken into account in the predictions and therefore it is assumed that all areas below the predicted high water levels are inundated. As a consequence of this limitation and the fact that the accuracy of these maps is very dependant on the digital terrain data used and many areas do not benefit from the improved accuracy of Lidar, the coastal flood plains illustrated should be regarded as ‘indicative’ of the general areas that are estimated to prone to flooding. The map is not suitable for determining the flood risk to a particular property or specific point location.

The Sea Flood Map contains two distinct layers namely Present Day and Climate Change. The Present Day map layer illustrates the extents of the coastal flood plains that have been estimated by the predictive model using input data that is representative of the current climate conditions and sea levels. It is an accepted scientific fact that sea levels are rising and that this will increase the coastal flood risk. Therefore, the Climate Change map layer has been produced to reflect the estimated coastal flood plain outlines for the year 2030 and are based on the best available predictions for sea levels and storm surges at that time.