The Planning System and Flood Risk Management - Offaly County ...

24Planning GuidelinesDevelopment in defended areas3.13 A defended area is a location that benefits from an existing flood relief schemeor flood defences that reduce the probability of flooding of the location. Landbehind such defences can be particularly vulnerable due to the speed offlooding when overtopping or a breach or other failure occurs. It is importantto note that a residual risk of flooding remains to such defended locationsand thus the sequential approach and the Justification Test apply to theseareas. The range of residual risks is described in Appendix A and B. Thepresence of defences can also increase the probability of flooding from causesother than river and coastal flooding, e.g. by preventing the discharge ofoverland flow or sewer flooding due to intense rainfall events, which are likelyto become more frequent as a result of climate change.3.14 Given this residual risk, planning authorities should apply the JustificationTest in each and every case, when considering development vulnerable toflooding in areas that benefit from such flood defences or relief schemes. Ifthe development, including infrastructure, passes Part 1 of the JustificationTest, the development of residual flood risk management strategies andmeasures (refer to Appendix B) can factor in the presence of flood defencesand their effectiveness during a flood event.Flooding and Strategic Environmental Assessment3.15 The Planning Guidelines for Strategic Environmental Assessment (SEA)(DEHLG, 2004) outline an integrated process for SEA and plan-making. SEAis required to be undertaken for Regional Planning Guidelines, developmentplans and variations, many local area plans and SDZ planning schemes.3.16 The SEA process provides a good practice framework for scoping andconsidering a range of planning and environmental issues, including floodingin the plan making process. The flood risk assessment should be integratedwith this process where a full environmental report is required. This floodrisk assessment should be undertaken as early as possible in the process sothat the SEA is fully informed of the flood risks and impacts of the proposedzoning or development (See Appendix A).Important elements of the process and report include:• scoping, which should identify likely and significant flooding issues;• consideration of flooding as one of the environmental criteria for thearea, if appropriate;• evaluation of strategic alternatives against the environmental criteria;