NI Coastal Erosion High Level Risk Appraisal

• Environment
• Geoscientific Information
• Oceans
• Planning / Cadastre

The potential for coastal erosion was assessed based upon a combination of published information regarding the bedrock geology and aerial photographs. The coastline was based the OSNI Large-scale NI Outline dataset and therefore contains public sector information licensed under the terms of the Open Government Licence v3.0 (http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/) Igneous rock (such as basalt) was classed as low potential for erosion. Sedimentary and metamorphic rocks were classed as medium potential for erosion category. Beaches with lower-lying land behind have been classified as having a high potential for erosion - these locations will be subject to sediment transport and hence net erosion or accretion during storms and other events

IMPORTANT - PLEASE READ Use limitations: It must be noted that there can be considerable variability within each category. For example, areas where the bedrock is sandstone have been classified as having medium potential for erosion, however, while these rocks are expected to erode, the rate of erosion may be so slow as not to cause a problem within the next century. Beaches with lower-lying land behind have been classified as having a high potential for erosion. These locations will be subject to sediment transport and hence net erosion or accretion during storms and other events. Such impacts do not necessarily mean that coastal erosion (defined here as the long-term retreat of a coastline) is occurring, as some sedimentary features are relatively stable in the long term if they are in equilibrium with their forcing conditions. Hence the potential for erosion is identified, based on geology and appearance and then substantiated, where possible, through references to papers, reports and other anecdotal information. Please note that not all areas indicated as at high risk of erosion are currently eroding; and in addition, it should be noted that the areas identified as at high risk of erosion or of high asset value may not be in need of defences. Further study is required in order to assess the state and integrity of sea defences in areas where high erosion risk and high asset value coincide. In addition, a more detailed assessment of the erosion risk in these areas would provide the evidence required to decide whether further coastal defences are required to protect these assets where no sea defences are currently present. The data available to produce this report was very limited and the assessment was therefore desktop only and is a high-level assessment. Consequently, the allocation of risk ranking and the determination of vulnerability has to be considered as preliminary. It is likely that further information will be required to inform coastal management decision making. A more detailed assessment is beyond the scope of the current study and would require scoring of individual assets combined with more detailed data and information on erosion potential. As a consequence, the figures presented may assist in prioritising resource to areas that require further study on coastal change. Vulnerability mapping will require revisiting following collation of the data identified in the Data Requirements. Despite the caution expressed above, the findings of the preliminary vulnerability assessment broadly align both with other assessments and anecdotal evidence as to where coastal erosion is a concern. One example is along the Antrim Coast where the areas at high risk of erosion are mainly the pocket beaches found between sections of cliff. The preliminary vulnerability assessment mapping could therefore be utilised to assist in the prioritisation of geographical areas requiring further detailed data collation and coastal erosion vulnerability assessment. The following priorities are considered the key tasks required to improve the understanding of coastal change in Northern Ireland: Improve coastal change baseline for NI; Delivery of a coordinated monitoring programme on coastal change; Collating, managing and making accessible key information; and Development of evolving robust coastal erosion vulnerability mapping. Display: For best visualisation it is recommended to display the Erosion Risk layer in a GIS as a thick line with Red-Amber-Green to represent High-Medium-Low risk, and to display the Vulnerability Assessment layers (Historic/Natural/Physical Assets) with a thin Red-Amber-Green line above. Credits: This spatial layer was prepared by Amey Consulting with HR Wallingford for the Department for Infrastructure (DfI) and the Department of Agriculture, Environment and Rural Affairs (DAERA).