Level 1 Strategic Flood Risk Assessment (SFRA) Has Been Prepared on Behalf of Herefordshire Council to Update the Level 1 SFRA Published in 2009
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HEREFORDSHIRE STRATEGIC FLOOD RISK ASSESSMENT LEVEL 1 APRIL 2019 HEREFORDSHIRE STRATEGIC FLOOD RISK ASSESSMENT LEVEL 1 Herefordshire Council DRAFT Project no: 70023685 Date: April 2019 – WSP Kings Orchard 1 Queen Street Bristol BS2 0HQ Tel: 0117 930 6300 www.wsp.com Q U A L I T Y M A N A G E M E N T ISSUE/REVISION FIRST ISSUE REVISION 1 REVISION 2 REVISION 3 Remarks Draft for comment Amended draft for Amended draft for Final comment consultation Date 15 March 2017 22 December 2017 19 April 2018 4 April 2019 Prepared by S. Haberfield S. Haberfield S. Haberfield S. Haberfield Checked by J. Goodwin J. Goodwin J. Goodwin J. Goodwin Authorised by J. Goodwin J. Goodwin J. Goodwin J. Hockenhull Project number 70023685 70023685 70023685 70023685 Report number 70023685-001 70023685-002 70023685-003 70023685-004 ii TABLE OF CONTENTS EXECUTIVE SUMMARY .............................................................................1 1 INTRODUCTION ...........................................................................2 1.1 PROJECT OVERVIEW ...................................................................................... 2 1.2 PURPOSE OF THE SFRA ................................................................................. 2 1.3 SCOPE OF THE SFRA ...................................................................................... 3 1.4 HEREFORDSHIRE – AN OVERVIEW ............................................................... 4 2 POLICY FRAMEWORK .............................................................. 13 2.1 NATIONAL POLICY ......................................................................................... 13 2.2 REGIONAL POLICY ........................................................................................ 19 2.3 LOCAL POLICY ............................................................................................... 24 2.4 ROLE AND RESPONSIBILITIES ..................................................................... 26 3 APPROACH TO THE SFRA ....................................................... 28 3.1 CONSULTATION AND ENGAGEMENT ......................................................... 28 3.2 PROPOSED USE ............................................................................................. 29 3.3 STRUCTURE .................................................................................................... 30 3.4 FLOOD RISK DEFINITIONS ............................................................................ 31 4 DATA AVAILABILITY ................................................................ 35 4.1 SUMMARY ....................................................................................................... 35 4.2 HEREFORDSHIRE COUNCIL FLOOD DATA ................................................ 35 4.3 ENVIRONMENT AGENCY FLOOD DATA ...................................................... 36 4.4 SEWERAGE COMPANY FLOOD DATA ......................................................... 39 4.5 LIMITATIONS ................................................................................................... 40 5 FLOOD RISK IN HEREFORDSHIRE ......................................... 41 5.1 SUMMARY ....................................................................................................... 41 Herefordshire Level 1 SFRA WSP Balfour Beatty Living Places Project No 70023685 April 2019 iii 5.2 CATCHMENT OVERVIEW ............................................................................... 41 5.3 FLOOD HISTORY ............................................................................................ 41 5.4 FLOOD DEFENCE SCHEMES ........................................................................ 44 5.5 ASSESSMENT OF FLOOD RISK .................................................................... 49 5.6 EMERGENCY PLANNING ............................................................................... 56 5.7 MAPPING THE IMPACTS OF CLIMATE CHANGE ........................................ 57 6 POLICY RECOMMENDATIONS AND GUIDANCE .................... 60 6.1 INTRODUCTION .............................................................................................. 60 6.2 THE SEQUENTIAL TEST ................................................................................ 63 6.3 THE EXCEPTION TEST ................................................................................... 66 6.4 ASSESSING FLOOD HAZARD ....................................................................... 69 6.5 CONSIDERING THE IMPACTS OF CLIMATE CHANGE ............................... 70 6.6 RESISTANCE AND RESILIENCE MEASURES .............................................. 77 6.7 BASEMENTS ................................................................................................... 79 6.8 ACCESS AND EVACUATION ......................................................................... 79 6.9 SUMMARY OF DEVELOPMENT CONTROL RECOMMENDATIONS ........... 80 6.10 DETAILED FLOOD RISK ASSESSMENT ....................................................... 86 6.11 PROPOSED DEVELOPMENT WITHIN FLOOD ZONE 3B – THE FUNCTIONAL FLOODPLAIN .......................................................................... 87 6.12 PROPOSED DEVELOPMENT WITHIN FLOOD ZONE 3A – HIGH PROBABILITY.................................................................................................. 88 6.13 PROPOSED DEVELOPMENT WITHIN ZONE 2 - MEDIUM PROBABILITY.................................................................................................. 90 6.14 PROPOSED DEVELOPMENT WITHIN ZONE 1 - LOW PROBABILITY ........ 91 6.15 LIAISON WITH THE ENVIRONMENT AGENCY AND HEREFORDSHIRE COUNCIL ......................................................................... 92 6.16 CONSENTS AND BUFFER ZONES ................................................................ 93 6.17 SUSTAINABLE DRAINAGE SYSTEMS (SUDS) ............................................ 93 6.18 EMERGENCY PLANNING ............................................................................... 96 Herefordshire Level 1 SFRA WSP Balfour Beatty Living Places Project No 70023685 April 2019 iv 7 CLOSING REMARKS ................................................................. 98 7.1 OVERVIEW OF THIS SFRA ............................................................................ 98 7.2 UPDATING THE SFRA .................................................................................... 98 T A B L E S TABLE 1.3.1 SCOPE OF THE SFRA .................................................................................... 3 TABLE 2.4.1 ROLE AND RESPONSIBILITIES ................................................................... 26 TABLE 5.3.1 SUMMARY OF NOTABLE HISTORIC FLOOD EVENTS .............................. 42 TABLE 5.3.2 JULY 2007 FLOODS ...................................................................................... 43 TABLE 5.3.3 SUMMER AND WINTER 2012 FLOODS ....................................................... 43 TABLE 5.3.4 SPRING 2014 FLOODS ................................................................................. 44 TABLE 5.7.1 PEAK RIVER FLOW ALLOWANCES ............................................................. 57 TABLE 5.7.2 NOMINAL ALLOWANCES PEAK RIVER LEVELS ........................................ 58 TABLE 6.3.1 NPPF VULNERABILITY CLASSIFICATIONS ................................................ 66 TABLE 6.3.2 FLOOD RISK VULNERABILITY AND FLOOD ZONE COMPATIBILITY ....... 67 TABLE 6.4.1 GUIDANCE ON DEBRIS FACTORS .............................................................. 69 TABLE 6.4.2 HAZARD TO PEOPLE CLASSIFICATION ..................................................... 70 TABLE 6.5.4 NOMINAL ALLOWANCES PEAK RIVER LEVELS ........................................ 74 TABLE 6.5.5 PEAK RAINFALL INTENSITY ALLOWANCE ................................................ 76 TABLE 6.9.1 SPATIAL PLANNING AND DEVELOPMENT CONTROL RECOMMENDATIONS ...................................................................... 83 F I G U R E S FIGURE 1.4.1 MAP OF HEREFORDSHIRE .......................................................................... 5 FIGURE 2.2.1 SUB-AREAS AND POLICY OPTIONS FOR THE WYE AND USK CFMP .. 20 FIGURE 2.2.2 SUB-AREAS AND POLICY OPTIONS FOR THE RIVER SEVERN CFMP ................................................................................................. 22 FIGURE 5.2.1 MAIN RIVER CATCHMENTS WITHIN HEREFORDSHIRE ........................ 41 FIGURE 6.2.1 APPLICATION OF THE SEQUENTIAL TEST ............................................. 64 FIGURE 6.3.1 APPLICATION OF THE EXCEPTION TEST ............................................... 68 FIGURE 6.5.1 EXAMPLE FOR DETERMINING APPROPRIATE CLIMATE CHANGE ASSESSMENT APPROACH ............................................................. 75 Herefordshire Level 1 SFRA WSP Balfour Beatty Living Places Project No 70023685 April 2019 v A P P E N D I C E S APPENDIX A OVERVIEW MAP OF HEREFORDSHIRE APPENDIX B MAP OF MAIN RIVERS IN HEREFORDSHIRE APPENDIX C STRATEGIC ASSESSMENT OF FLOOD RISK AT STRATEGIC DEVELOPMENT SITES APPENDIX D COUNTY-WIDE STRATEGIC FLOOD RISK MAPS APPENDIX E HEREFORD LOCAL MAPS APPENDIX F LEOMINSTER LOCAL MAPS APPENDIX G ROSS ON WYE LOCAL MAPS APPENDIX H LEDBURY LOCAL MAPS APPENDIX I BROMYARD LOCAL MAPS APPENDIX J KINGTON LOCAL MAPS APPENDIX K HEREFORDSHIRE LOCAL FLUVIAL FLOOD MAPPING APPENDIX L AREAS AT RISK OF RESERVOIR FLOODING APPENDIX M LOCATION OF SAND AND GRAVEL DEPOSITS IN HEREFORDSHIRE APPENDIX N E.A. FLOOD WARNING AND FLOOD ALERT AREAS Herefordshire Level 1 SFRA WSP Balfour Beatty Living Places Project