Managing Flood Risk Revised Strategic Flood Risk Assessment Levels 1 and 2
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. Poole Local Plan Managing Flood Risk Revised Strategic Flood Risk Assessment Levels 1 and 2 November 2017 Poole Local Plan. Level 1 & 2 Strategic Flood Risk Assessment. November2017 2 Contents 1. Introduction ............................................................................................................................... 4 Part 1: Level 1 Strategic Flood Risk Assessment ............................................................................ 7 2. Policy Context ........................................................................................................................... 9 3. The Borough of Poole Study Area .......................................................................................... 11 4. Flood Risk ............................................................................................................................... 13 Sources of Flood Risk ................................................................................................................ 13 Flood Zones ............................................................................................................................... 13 Historic Flooding in Poole ........................................................................................................... 22 Coastal Change .......................................................................................................................... 25 5. Flood Management and Mitigation .......................................................................................... 27 Flood Defences .......................................................................................................................... 27 Poole Bay, Poole Harbour and Wareham Flood and Coastal Erosion Risk Management – Final Strategy (December 2014) ......................................................................................................... 31 Local Flood Defence Schemes ................................................................................................... 31 6. Development Management ..................................................................................................... 35 Residual Flood Risk ................................................................................................................... 36 Emergency Planning .................................................................................................................. 37 Flood Warning Areas .................................................................................................................. 38 Flood Risk Assessments ............................................................................................................ 40 Sustainable Urban Drainage Systems (SuDS) ........................................................................... 40 7. Climate Change ...................................................................................................................... 43 8. Flood risk assessment of potential development sites in Poole .............................................. 45 Summary .................................................................................................................................... 48 Part 2: Level 2 Strategic Flood Risk Assessment .......................................................................... 49 9. The need for a Level 2 Strategic Flood Risk Assessment....................................................... 50 Application of the Sequential Test - Central Poole Area ............................................................. 50 Analysis of housing capacity in Poole ........................................................................................ 51 Application of the Exception Test ............................................................................................... 55 Flood Defences .......................................................................................................................... 56 Analysis of Flood Risk within the Poole Town Centre and Twin Sails regeneration area Sequential Test application area – current day to 2133 ............................................................. 57 Summary conclusions ................................................................................................................ 64 Sequential Test of other site allocations ..................................................................................... 65 Application of the Sequential Test and Exception Test outside of the Town Centre study area . 65 10. Glossary of Terms ................................................................................................................ 66 11. Appendix 1 - Flood Risk Vulnerability Classification ............................................................. 68 12. Appendix 2 - Site Assessment Flood Risk Summary ........................................................... 69 13. Appendix 3 – Nature and condition of flood defences and coastal erosion protection structures in Poole ......................................................................................................................... 72 Poole Local Plan. Level 1 & 2 Strategic Flood Risk Assessment. November2017 3 1. Introduction 1. It is predicted that as a consequence of climate change, the incidence and severity of flooding will increase over time as a result of rising sea levels and more frequent severe storms that bring higher intensity rainfall and increased run-off from land and buildings. This will result in increased vulnerability of Poole’s coastal and harbour areas to the risk of tidal flooding and to other areas of the borough from rivers, streams and watercourses as higher flows and levels, as a consequence of storm events, cause sewers and drains to exceed capacity more frequently than at present. 2. Opportunities for growth in Poole are constrained due to the coast and harbour to the south, internationally designated heathland habitats and Green Belt to the north and west, whilst to the east the Borough merges seamlessly with Bournemouth. Within this context, the town centre including the Twin Sails regeneration area, areas at risk of tidal flooding, provide the most sustainable opportunities for significant development to meet future needs for housing and employment. Consideration of flood risk is therefore key to Poole’s strategy for the delivery of growth over the coming years. 3. As the assessment of the risks associated with flooding is an ongoing process, it is appropriate that SFRA documents are reviewed and updated as necessary. The review of Poole’s currently adopted development plan documents, primarily the Poole Core Strategy (adopted February 2009); Poole Site Specific Allocations and Development Management Policies DPD (adopted April 2012) and Delivering Poole’s Infrastructure DPD (adopted April 2012), provides such an opportunity. 4. This document therefore provides an update to the Strategic Flood Risk Assessment (SFRA) for Poole, incorporating both Level 1 and 2 requirements. Poole Local Plan. Level 1 & 2 Strategic Flood Risk Assessment. November2017 4 What is Strategic Flood Risk Assessment? 5. Planning Practice Guidance (March 2014), defines a Strategic Flood Risk Assessment (SFRA) as:- “a study carried out by one or more local planning authorities to assess the risk to an area from flooding from all sources, now and in the future, taking account of the impacts of climate change, and to assess the impact that land use changes and development in the area will have on flood risk.” 6. The aim of a SFRA is to reduce the risk to people and both the built and natural environment from flooding. It does this by discouraging further development within areas at high risk of flooding and by providing guidance for the control of surface water run-off. 7. A SFRA provides information on flood risk issues and assesses the different levels, extent and nature of flood risk and flooding, and maps this to assist with the preparation of local development plan documents and in the assessment of planning applications. 8. The SFRA is used to:- determine the variations in risk from all sources of flooding across an area, and also the risks to and from surrounding areas in the same flood catchment; inform the sustainability appraisal of a Local Plan, so that flood risk is fully taken into account when considering allocation options and in the preparation of plan policies, including policies for flood risk management to ensure that flood risk is not increased; apply the Sequential Test and, where necessary, the Exception Test when determining land use allocations; identify the requirements for site-specific flood risk assessments in particular locations, including those at risk from sources other than river and sea flooding; determine the acceptability of flood risk in relation to emergency planning capability; and consider opportunities to reduce flood risk to existing communities and developments through better management of surface water, provision for conveyance and of storage for flood water. The requirement for Strategic Flood Risk Assessment? 9. The NPPF states that:- “Local Plans should be supported by Strategic Flood Risk Assessment and develop policies to manage flood risk from all sources, taking account of advice from the Environment Agency and other relevant flood risk management bodies….”.1 10. There are two levels of Strategic Flood Risk Assessment that reflect the likely risk of flooding from all sources and development