PENWITH DISTRICT COUNCIL PENWITH LOCAL DEVELOPMENT FRAMEWORK STRATEGIC FLOOD RISK ASSESSMENT Level 1 Coarse Assessment Part 1 August 2007 Sustainable Development and Improvement Contact This report is published by the: Sustainable Development Policy Team Sustainable Development and Improvement Penwith District Council St Clare Penzance Cornwall TR18 3QW For further information or advice on the contents of this report please contact: Greg Clouter Sustainable Development Policy Monitoring Officer Email; [email protected] Tel: (01736) 336828 EXECUTIVE SUMMARY • The Strategic Flood Risk Assessment (SFRA) for Penwith District Council has been undertaken to provide a detailed and robust assessment of the extent and nature of flood risk in the district and the implications this has for land use planning. • The SFRA explains the criteria for the submission of planning applications in the future and for guiding subsequent development control decisions. • The SFRA has specific objectives to: • Provide a reference and policy document to inform in the preparation the new Local Development Framework (LDF) which will replace the adopted Penwith Local Plan; • Provide a reference and policy document to advise and inform private and commercial developers of their obligations as defined by the latest planning requirements (PPS25); • Ensure that Penwith District Council meets its obligations as outlined in the latest planning requirements (PPS25); • Enable consistent and sustainable decisions to be made by the local planning authority on issues relating to flood risk. • The principle outputs of the SFRA is provided in two parts: • This SFRA report; • A Geographic Information System (GIS) Package to provide the spatial data in electronic format for ease of access and supplying up to date information. • The spatial information provided on the GIS package consists of the following datasets: • Flood Risk and Defence Map – presents areas currently at flood risk as defined by the Environment Agency flood zone mapping and existing and proposed flood defences in the district; • Climate Change Impact Map – presents areas identified as being at future risk of flooding due to the impact of climate change. This takes into account the effect of sea level rise, fluvial flooding on Environment Agency flood zones, and fluvial flooding on potential flood risk areas which currently lie outside of the scope of the Environment Agency flood zones. • The scope of the spatial information of the SFRA covers the entire district, supplying sufficient data for an overall view of flood risk in the study area for strategic planning purposes. CONTENTS Executive Summary Part 1 Context and Scope of the Assessment 1-9 1. Introduction 2-4 2. Data Collection 5-6 3. Study Output 7-9 Part 2 Level 1 Coarse Assessment Part 1 10-58 Part 1 Assessment 11 1. Process 1: Problem Formulation 12-13 2. Process 2.a: Tiered Risk Assessment 14 Process 2a1: Level 1 Coarse Assessment 14-22 3. Process 2b: Stages of Risk Assessment 23 Process 2b1: Hazard Identification 23-41 4. Processes 2b2-2b5: Consequence and Significance of Flood Risk 42-47 5. Process 2a2: Prioritisation of Risk 48-51 6. Process 2a3: Level 2 Intermediate Assessment 52-54 7. Process 2a4: Level 3 Detailed Assessment 55-56 8. Process 3: Options Appraisal 57-58 Part 3 Appendices 59-78 Appendix A: Compensatory Flood Storage/Conveyance 60-61 Appendix B: Surface Water Runoff Rates 62-63 Appendix C: Flood Warning and Evacuation Planning 64 Appendix D: Organisational Responsibilities and Flood Risk 65-66 Appendix E: Flood Guidance for Planning Officers 67-68 Appendix F: Allocated Sites and Flood Risk 69 Appendix G: The Sequential and Exception Tests 70-73 Appendix H: Flood Risk Assessments 74 Appendix I: Penwith Area Profile 75-78 Glossary of Terms 79-80 References 81 PART 1 CONTEXT AND SCOPE OF THE ASSESSMENT Page 1 1 INTRODUCTION Context - Flood Risk and the Local Development Framework 1.1 Under the new emerging planning system, local authorities are required to undertake a Strategic Flood Risk Assessment (SFRA) to provide an evidence base to inform and guide in the preparation of Local Development Framework (LDF) documents in terms of assessing the implications of flood risk on spatial land use planning within their administrative areas. This Strategic Flood Risk Assessment is part of the evidence base for the Penwith District Council Local Development Framework process and aims to inform and provide general guidance on matters relating to flood risk within the district to development control, developers and the general public. 1.2 The Environment Agency guidance to local planning authorities on Strategic Flood Risk Assessments defines the purpose of the assessment as: 'To identify the areas within a development plan that are at risk of flooding. To identify and detail those factors that are relevant to current and future flood risks and to outline policies to be applied to such areas to minimise and manage that risk'. 1.3 Planning Policy Statement 1: Delivering Sustainable Development , requires local planning authorities to facilitate sustainable patterns of development by avoiding areas of flood risk and accommodating for the potential impact of climate change. Reducing the threat of flooding therefore achieves sustainable development and sustainable communities by contributing to a better quality of life. 1.4 Planning Policy Statement 12: Local Development Frameworks states; At the earliest stage in the preparation of the development plan document, and particularly for the preparation of the Core Strategy, the local planning authority should gather evidence about their area. This may include studies to be undertaken or commissioned on for example...areas of flooding... This evidence will be relied upon by the local planning authority in testing the soundness of the development plan document at independent examination. 1.5 Planning Policy Statement 25: Development and Flood Risk, requires that sites should be allocated in descending order of flood risk when reviewing development plans for the new LDF system. This constitutes a risk based approach which is determined by the application of the Sequential Flood Risk Test (SFRT). Penwith District Council is currently in the initial stages of preparing its LDF portfolio in line with the draft South West Regional Spatial Strategy (SWRSS) covering the development plan period from 2006-2026. The SFRA will guide decisions on allocating land in the new LDF system, informing in the preparation of both strategic and development control policies in enabling the application of the SFRT. 1.6 Development and Flood Risk: A Practice Guide Companion to PPS 25, Living Draft (February 2007) states: A level 1 SFRA should be sufficiently detailed to allow ` application of the Sequential Test on the basis of Table D1 of PPS25 and to identify whether application of the Exception Test is likely to be necessary. The information may be used to assess how any environmental objectives relating to flood, as defined in the Sustainability Appraisal, may be affected by additional development. This Page 2 should principally be a desk based study making use of existing information. 1.7 Regional Spatial Strategy South West (RSS SW) The draft RSS SW is the strategic spatial planning document proposed by the South West Regional Assembly (SWRA) covering the South West Region from 2006 to 2026 (currently under consultation until August 2006). The RSS has one specific policy regarding flood risk, Policy F1, which states: Taking account of climate change and the increasing risk of coastal and river flooding, the priority is to: • Defend existing property and, where possible, locate new development in places with little risk of flooding; • Protect flood plains and land liable to tidal or coastal flooding from development; • Follow a sequential approach to development in flood risk areas; • Use development to reduce the risk of flooding through location, layout and design; • Relocate existing development from areas of the coast at risk, which cannot realistically be defended; and • Identify areas of opportunity for managed realignment to reduce the risk of flooding and create new wildlife areas. SFRA Objectives 1.8 Planning Policy Statement 25: Development and Flood Risk) requires Councils to provide a detailed and robust evidence base for requesting site specific Flood Risk Assessments. These requirements will be fulfilled in the five key objectives of the SFRA. • To prepare flood risk evidence base to inform in the preparation of the LDF. • To meet requirements of latest planning guidance (PPS25). • To provide a flood risk policy reference for developers and the general public. • To inform development control on flood risk issues relating to applications. • To provide an evidence base for requesting future site specific Flood Risk Assessments from the Environment Agency. Status and Format of the SFRA 1.9 A SFRA is divided into two parts to reflect the two functions of planning, which is further divided into three levels of detail. Part 1 relates to spatial planning covering the entire LPA area to feed into the preparation of Development Plan Documents (DPDs). The Part 1 element consists of two levels of detail: Coarse Assessment Level 1; and an Intermediate Assessment Level 2. The Level 2 includes additional detail to the Level 1 when required. Part 2 relates to the regulation and control element of planning and will be undertaken when required to inform the preparation of Supplementary Planning Documents (SPDs) covering specific development areas. This constitutes a Detailed Assessment Level 3. Page 3 Table 1 The LDF Process and Flood Risk Function Spatial Planning Regulation and Control Implementation Approach Local Development Supplementary Planning Documents (LDDs) Documents (SPDs) Assessment Type Strategic Flood Risk Assessment (SFRA) Part 1 Part 2 Level 1 Level 2 Level 3 Coverage Full coverage of LPA area Planned development area 1.10 This report is the level 1 Coarse Assessment, Part 1 of the SFRA for Penwith District Council 1.11 The format for this SFRA comprises of this Level 1 Coarse Assessment and a series of mapped datasets in a Geographic Information System (GIS) package.