Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
Stage 2 SFRA - Flood Risk Assessment
3.1 Introduction Stage 2 SFRA (flood risk assessment) has been undertaken to: Confirm the sources of flooding that may affect zoned and adjacent areas; Appraise the adequacy of existing information as identified by the Stage 1 SFRA; and Scope the extent of the risk of flooding through the preparation of flood zone maps. 3.2 Findings and Adequacy of Existing Information and Delineation of Flood Zones Desk and in-field studies were undertaken taking into account the following factors: OPW’s CFRAMS fluvial flood extent mapping and other predictive indicators; Historical indicators of flood risk; Documented local Council knowledge of flood risk; The potential source and direction of flood paths from the sea and rivers and streams; Vegetation indicative of flood risk; and The locations of topographic/built features that coincide with the flood indicator related boundaries/topographical survey. Within the annual exceedance probabilities specified by the Flood Guidelines for Flood Zones A and B, there are elevated levels of flood risk throughout the City, as shown in Appendix II . 3.3 Flood Risk Zone Mapping Flood Risk Zone maps have been produced taking into account the findings of the Stage 1 and Stage 2 SFRA desk and in field studies as identified above 4 . The maps are provided in Appendix II and identify Flood Zone A (darker blue) and Flood Zone B 5 (lighter blue). All other areas fall within Flood Zone C. As per the Guidelines, the flood zones in Cork City are as follows: Flood Zone A – where the probability of flooding from rivers and the sea is highest (greater than 1% or 1 in 100 for river flooding or 0.5% or 1 in 200 for coastal flooding); Flood Zone B – where the probability of flooding from rivers and the sea is moderate (between 0.1% or 1 in 1000 and 1% or 1 in 100 for river flooding and between 0.1% or 1 in 1000 year and 0.5% or 1 in 200 for coastal flooding); and Flood Zone C – where the probability of flooding from rivers and the sea is low (less than 0.1% or 1 in 1000 for both river and coastal flooding). Flood Zone C covers all other areas that are not in zones A or B.
4 Including taking into account predictive and historical indicators of flood risk, documented local Council knowledge of flood risk, the potential source and direction of flood paths from rivers and streams, vegetation indicative of flood risk and the locations of topographic/built features that coincide with the flood indicator related boundaries/topographical survey. 5 As identified by the Guidelines, in rivers with a well-defined floodplain or where the coastal plain is well defined at its rear, the limits of Zones A and B will virtually coincide. Zone B will only be significantly different in spatial extent from Zone A where there is extensive land with a gentle gradient away from the river or the sea.
CAAS for Cork City Council
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