Strategic Flood Risk Assessment
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City of York Local Development LDF Framework Strategic Flood Risk Assessment June 2007 Evidence Base City of York Council Strategic Flood Risk Assessment Engineering Consultancy Draft Report City of York Council Strategic Flood Risk Assessment York Consultancy 1 City of York Council Strategic Flood Risk Assessment Engineering Consultancy Draft Report Contents GLOSSARY..................................................................................................................... 6 ABBREVIATIONS ............................................................................................................ 8 EXECUTIVE SUMMARY................................................................................................. 10 1 INTRODUCTION ..................................................................................................... 15 1.1 Background.............................................................................................................................................. 15 1.2 Purpose of the Assessment ................................................................................................................... 15 1.3 Contents .................................................................................................................................................... 16 2 BACKGROUND ...................................................................................................... 17 2.1 River Network ......................................................................................................................................... 17 2.2 Broad Physical Characteristics........................................................................................................... 18 2.3 Topography, Geology, Soils and Hydrogeology............................................................................. 18 2.4 Existing Flood Defences ........................................................................................................................ 18 2.5 Climatic Change Influences on Flooding ......................................................................................... 19 2.6 Policy Background................................................................................................................................. 20 2.7 European Context .................................................................................................................................. 20 2.8 National Context ..................................................................................................................................... 21 2.9 Risk-Based Approach............................................................................................................................ 21 2.10 The Sequential Test................................................................................................................................21 2.11 Exception Test......................................................................................................................................... 22 2.12 Brownfield Development...................................................................................................................... 22 2.13 Regional Context .................................................................................................................................... 25 2.14 Strategic and Local Planning Context .............................................................................................. 26 2.15 EA High Level Target 5 (HLT5) ........................................................................................................ 26 2.16 EA Standing Advice: Development & Flood Risk (England)..................................................... 27 2.17 Current Environment Agency Flood Policy.................................................................................... 27 2.18 City of York Council Policy Statement on Flood and Coastal Defence.................................. 29 3 FLOOD RISK IN YORK – KEY ISSUES .................................................................... 30 2 City of York Council Strategic Flood Risk Assessment Engineering Consultancy Draft Report 3.1 The River and Watercourse Network ............................................................................................... 30 3.2 Flood Risk Zones .................................................................................................................................... 31 3.3 City of York Council’s Emergency Planning – Flood Risk........................................................ 33 3.4 Rapid Inundation Zones (RIZ) ........................................................................................................... 34 3.5 Flood Depth Mapping ........................................................................................................................... 37 3.6 Climatic Change Influences on Flooding ......................................................................................... 38 3.7 Freeboard Allowance ............................................................................................................................ 38 3.8 River Ouse................................................................................................................................................ 39 3.9 River Foss................................................................................................................................................. 53 3.10 River Derwent ......................................................................................................................................... 58 4 APPROACH TO FLOOD RISK................................................................................. 60 4.1 Policy Recommendations and Guidance.......................................................................................... 60 4.1.a Policy Recommendations for Forward Planning ...................................................................... 60 4.1.b Guidance for Development Control and the Consideration of Planning Applications...75 4.1.c General Drainage Guidance............................................................................................................ 84 4.2 Proposed Development within Zone 3 .............................................................................................. 86 5 THE SEQUENTIAL TEST AND EXCEPTION TEST................................................... 89 5.1 The Sequential Test and Exception Test for Forward Planning ............................................... 89 5.2 The Sequential Test and Exception Test for Development Control ......................................... 91 APPENDIX 1: SOURCES OF INFORMATION ................................................................. 96 APPENDIX 2: CONSULTEES ......................................................................................... 98 APPENDIX 3: EA HIGH LEVEL TARGET 12 DEVELOPMENT & FLOOD RISK...............100 APPENDIX 4: CITY OF YORK COUNCIL POLICY STATEMENT ON FLOOD ................102 APPENDIX 5: CITY OF YORK DRAFT LOCAL PLAN INCORPORATING THE 4TH SET OF CHANGES – DEVELOPMENT CONTROL LOCAL PLAN : APPROVED APRIL 2005”. POLICY GP15A : DEVEL OPMENT AND FLOOD RISK ..................................................110 APPENDIX 6: PPS25 – ‘DEVELOPMENT AND FLOOD RISK’ ........................................112 APPENDIX 7: ENVIRONM ENT AGENCY STANDING ADVICE .......................................114 3 City of York Council Strategic Flood Risk Assessment Engineering Consultancy Draft Report Figures (Please see accompanying map booklet) Figure 1: Main River and Tributary Network in York Figure 2: River Ouse and Foss Catchment Boundaries….…………………………...134 Figure 3: River Derwent Catchment Boundary…………………………….…………..135 Figure 4: Internal Drainage Board Boundaries Figure 5: River Ouse Yearly Maximum Flood Levels Figure 6: River Zones in York Figure 7: Existing York Flood Defences………………………………………………..136 Figure 8: Environment Agency Flood Cell Plan Figure 9: Environment Agency Flood Zones Figure 10: Local Plan Map Extracts Figure 11: Flood Risk Areas within Zone 2 & 3 (key plan) Figure 11a: Flood Risk Areas within Zone 2 & 3 – North West area Figure 11b: Flood Risk Areas within Zone 2 & 3 – Strensall area Figure 11c: Flood Risk Areas within Zone 2 & 3 – Poppleton area Figure 11d: Flood Risk Areas within Zone 2 & 3 – City Centre area Figure 11e: Flood Risk Areas within Zone 2 & 3 – Dunnington area Figure 11f: Flood Risk Areas within Zone 2 & 3 – Copmanthorpe area Figure 11g : Flood Risk Areas within Zone 2 & 3 – Elvington area Figure 12: Plan view of Danger to People from Breach Scenario (in body of report)…..35 Figure 13: Sectional view of Danger to People from Breach Scenario (in body of …….36 report) Figure 14: Flooded Domestic Properties in 2000 – Key Plan Figure 14a: Flooded Domestic Properties in 2000 – Rawcliffe Figure 14b: Flooded Domestic Properties in 2000 – City Centre and Clementhorpe Figure 14c: Flooded Domestic Properties in 2000 – Fulford Figure 14d: Flooded Domestic Properties in 2000 – Bishopthorpe Figure 14e: Flooded Domestic Properties in 2000 – Naburn and Acaster Malbis Figure 14f: Flooded Domestic Properties in 2000 – Elvington Tables Table 1.1: Environment Agency Flood Risk Standing Advice for England (PPS25) Version 1.0 – May 2007 (Flood Risk Matrix) ...................................................................................... 14 Table 2.1: PPS25 Flood Zones