Fingal East Meath Flood Risk Assessment & Management Study (FEM FRAMS) Flood Risk Management Plan July 2014 .ie fingal Fingal East Meath Flood Risk Assessment and Management Study Flood Risk Management Plan ii Fingal East Meath Flood Risk Assessment and Management Study Flood Risk Management Plan Table of contents Table of contents .................................................................................................................. i List of abbreviations ........................................................................................................ viii Acknowledgements ............................................................................................................. x Executive Summary ........................................................................................................... xi 1. Introduction and background ................................................................................. 1 1.1. Background .......................................................................................................... 1 1.2. Aims and Scope ................................................................................................... 2 1.3. Flood risk management policies ............................................................................ 3 1.4. Interface with other studies ................................................................................... 6 2. Involvement of external parties .............................................................................. 7 2.1. Overview .............................................................................................................. 7 2.2. Provision of information ........................................................................................ 7 2.3. Stakeholder consultation ....................................................................................... 7 2.4. Public consultation ................................................................................................ 8 2.5. Final consultation stage ........................................................................................ 9 3. River and catchment description ......................................................................... 10 3.1. Overview of the study area ................................................................................. 10 3.2. Topography, geology and soil and drainage ........................................................ 12 3.3. Land use and land management ......................................................................... 13 3.4. Hydrology and tides ............................................................................................ 15 4. Hydrological analysis overview ........................................................................... 19 4.1. Overview ............................................................................................................ 19 4.2. Key Points .......................................................................................................... 19 5. Flood hazard assessment .................................................................................... 22 5.1. Introduction......................................................................................................... 22 5.2. Historic flood hazard ........................................................................................... 22 5.3. Current flood hazard ........................................................................................... 24 5.4. Future flood hazard............................................................................................. 34 5.5. Defence failures .................................................................................................. 39 iii Fingal East Meath Flood Risk Assessment and Management Study Flood Risk Management Plan 5.6. Blockage of structures ........................................................................................ 39 5.7. Groundwater flood hazard .................................................................................. 39 5.8. Pluvial flood hazard ............................................................................................ 40 6. Flood risk assessment ......................................................................................... 42 6.1. Introduction......................................................................................................... 42 6.2. Flood risk receptor maps .................................................................................... 42 6.3. Risk to human health .......................................................................................... 43 6.4. Risk to the environment ...................................................................................... 44 6.5. Cultural heritage ................................................................................................. 46 6.6. Risk to critical infrastructure ................................................................................ 46 6.7. Economic flood risk............................................................................................. 47 6.8. Existing flood risk management .......................................................................... 51 7. Flood risk management options .......................................................................... 53 7.1. Introduction......................................................................................................... 53 7.2. Establish the decision making framework and evidence base .............................. 54 7.3. Assess flood risk within each assessment unit .................................................... 56 7.4. Staged assessment process ............................................................................... 56 7.5. Preferred options ................................................................................................ 59 7.6. Cohesive options ................................................................................................ 62 7.7. Assessment of potential options for IRRs ............................................................ 62 7.8. Flood risk areas not included in the preferred options .......................................... 63 8. Environmental considerations ............................................................................. 64 8.1. Introduction......................................................................................................... 64 8.2. Environmental constraints and opportunities in the study area ............................ 65 8.3. Strategic Environmental Assessment .................................................................. 66 8.4. Habitats Directive Appropriate Assessment ......................................................... 69 9. Flood risk management strategy ......................................................................... 70 9.1. Introduction to the Strategy ................................................................................. 70 9.2. Components of the Fingal East Meath FRMP ...................................................... 72 9.3. Non-structural measures ..................................................................................... 75 iv Fingal East Meath Flood Risk Assessment and Management Study Flood Risk Management Plan 9.4. Structural Measures ............................................................................................ 81 9.5. Individual risk receptors ...................................................................................... 82 9.6. Assessment of the Plan components .................................................................. 84 9.7. Pluvial flooding ................................................................................................... 90 9.8. Prioritisation and Implementation of the FRM Plan .............................................. 90 9.9. Monitoring, review and evaluation ....................................................................... 96 Appendices Appendix A: List of Stakeholders Appendix B: List of Objectives, indicators and targets Appendix C: Weighting of objectives and scoring of flood risk management options Appendix D: Option description sheets Appendix E: List of culverts for proactive maintenance by the Local Authorities Appendix F: List of Reports prepared for this project v Fingal East Meath Flood Risk Assessment and Management Study Flood Risk Management Plan List of Figures (within this report) Figure 1-1 Flow chart setting out the project activities ............................................................ 2 Figure 3-1 Watercourses and urban areas within the Fingal East Meath study area (Refer to Figure 1 at the back of the report for more detail) ................................................................. 11 Figure 3-2 Surface geology (sub-soils) within the study area (Source: EPA) ........................ 13 Figure 3-3 Land use within the study area (Source: EPA Corine land cover database 2006) 14 Figure 3-4 The hydrological cycle ........................................................................................ 16 Figure 3-5 Mean annual rainfall (mm) from 1961 – 1990 (Source www.meteireann.ie) ......... 16 Figure 4-1 Hydrometric stations in and around the study area .............................................. 20 Figure 4-2 Sample sub-catchment boundaries ....................................................................