Liverpool City Council Strategic Flood Risk
Total Page:16
File Type:pdf, Size:1020Kb
Liverpool City Council Strategic Flood Risk Assessment (SFRA) January 2008 Contents Section 1 – Introduction Section 2 – Liverpool context Section 3 – Policy context Section 4 – Roles and responsibilities Section 5 – Flood Risk Assessment - Background - Risk of flooding - Flood Defences - Residual Risk - Extreme Events and Climate Change Section 6 - Spatial Development and Flood Risk Section 7 - Summary and conclusions Appendices Appendix A – Methodology and sources of information Appendix B – Guidance for Developers and Development Control Appendix C – RSS and Core Strategy Issues and Options Appraisal List of Figures Figure 1: Location map Figure 2: Flood Risk Vulnerability and Flood Zone ‘Compatibility’ (Table D.3 – PPS25) Figure 3: Liverpool Bay Shoreline Management Plan (SMP) - Sub Cell 11a - Great Ormes Head to Formby Point Figure 4: CFMP Boundaries Figure 5: Future boundary of SMP Figure 6: Roles and Responsibilities in flood risk - Liverpool Figure 7: Location of Low-Water in the Inner Mersey Estuary between 1956 and 1967 Figure 8: Flood Risk Zones for Mersey Estuary Catchment Figure 9: External DG5 for Mersey Estuary Catchment Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 1 - List of Tables Table 1: Key features and actions proposed within Draft Mersey Estuary CFMP for Liverpool Table 2: River Alt and Crossens - assessment of flood risk to people and economic damages Table 3: Rivers and Ordinary watercourses within each catchment Table 4a: Summary of Culverts – information from 1989 study that matches with 1999 study Table 4b: Summary of Culverts – information from 1989 study that does not match with 1999 study Table 5: Tidal levels in Liverpool (Gladstone Dock) Table 6: Historical information for the Environment Agency Flood Risk Zones Table 7: Historical areas of flooding Table 8: Flood locations supplied by Highways Table 9: Condition of Culverts Table 10: Incidences of sewer flooding Table 11: Risk of flooding to and from adjoining authorities List of Maps Map 1: Natural features – topography and watercourses Map 2a: Watercourses – main rivers, canal and catchments Map 2b: Watercourses – main rivers and ordinary watercourses from 1989 Watercourse Flood Alleviation Study and catchments Map 2c: Watercourses – main rivers and ordinary watercourses from 1999 Culverted Watercourse Study Map 3: Culverts Map 4a: Environment Agency flood risk zones – tidal flood risk Map 4b: Environment Agency flood risk zones – tidal and river flood risk Map 5: Flood Risk Zone 3: Estimated functional floodplain (3b) and High Probability Area (3a) Map 6: Historical flooding areas Map 7: Condition of culverts – where information is available, the areas of poorest condition are identified Map 8: Historical sewer flooding Map 9: Summary of identified floodrisk Map 10: Risk of flooding in and from adjoining authorities Map 11: Flood Defences – e.g. river wall, Greenfield sites and open spaces, levees Map 12: Strategic development areas, UDP Allocations and Flood risk Map 13: Predicted Extreme Tide Levels in 2115 Map 14: Predicted Extreme River Levels (Flood Risk Zone 2) Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 2 - 1 Introduction 1.1 This SFRA (Strategic Flood Risk Assessment) has been carried out by Liverpool City Council Planning Policy Department in order to fulfil the requirement set out in Planning Policy Statement (PPS) 251. This document has been undertaken between June 2006 and January 2008. 1.2 The SFRA is a tool that plays an important role in delivering sustainable development for the City of Liverpool, taking account of flood risk issues and climate change. The main objectives of this SFRA are to: • Identify land at risk of flooding in Liverpool and the degree of risk from river, sea and other sources • Reduce flood risk from and to new development through location, design and mitigation measures • Inform policy formulation and the Sustainability Appraisal for the emerging Local Development Framework concerning land use in flood risk areas • Provide a framework for development control officers and developers for dealing with the flood risk in development proposals 1.3 It is an important distinction that the function of the SFRA is to minimise the risk of flood to new developments and to reduce existing flood risks where possible. The risk of flooding to existing buildings is not within the remit of this assessment. 1.4 It is also important to note that this document is a strategic assessment. Detailed site specific flood risk assessments will still be required in line with PPS25. This assessment also highlights areas where further investigation may be required. 1.5 The role and responsibilities of different agencies concerning floodrisk is complex. This document has been undertaken by Liverpool City Council, but with the assistance of key partners including the Environment Agency, Liverpool 2020, United Utilities and Enterprise-Liverpool. 1.6 The structure of this SFRA builds up the picture of flood risk within Liverpool, starting with the Liverpool context, highlighting for example the need for urban renewal balanced with the need to address any identified flood risks. The policy context (section 3) sets out the main documents which influence the preparation of this SFRA and provides important background information. Due to the complexities of roles and responsibilities, there is also a summary flow chart which is designed to aid the development process, ensuring different agencies are aware of other agencies responsibilities. 1 Planning Policy Statement (PPS) 25 – Development and Floodrisk (2006) - DCLG Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 3 - 1.7 The key section of the document is section 5, the flood risk assessment. This provides basic background information, e.g. the locations of watercourses and culverts and then identifies where the key areas of flood risk are e.g. Environment Agency indicative flood risk maps and historical areas of flooding. This provides the basis in which to identify the level of flood risk in strategic areas (discussed in section 6) but also provides the background information for more detailed site specific flood risk assessments. Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 4 - Figure 1: Location Map 2 Liverpool Context 2.1 Liverpool is located on the River Mersey in the North West of England. It covers an area of 112 square kilometres. 2.2 Liverpool is a predominantly Knowsley urban area, with a population of 444,500 (2004 population Sefton estimate). The City has seen St. Helens significant change over the past Liverpool century including a population decline from its peak in 1931 of 846,101 to the present day. Wirral Halton 2.3 The city has a history strongly linked with its river, the Mersey, providing an international seaport and maritime trade, between the 18th and 20th Century. However, the 1980s industrial crisis led to a severe economic decline within Liverpool, the legacy of which is still a major issue today. 2.4 Over the years, the City has mounted a succession of major housing regeneration and redevelopment programmes to address these problems, dealing variously with slum clearance and housing stock rehabilitation. Areas of the city are now designated as priorities for action under the government’s Housing Market Renewal Initiative (HMRI), which is a long-term programme to transform those inner city neighbourhoods dominated by unpopular housing through a comprehensive regeneration process, including housing redevelopment and refurbishment on a major scale. 2.5 Despite these issues, Liverpool is a regional centre for financial and professional services, retail provision, tourism, higher education, hi-tech industries, manufacturing and transportation. The Mersey Ports and Liverpool John Lennon Airport are key transport hubs and perform a central role in the City’s economy. 2.6 The City Council’s aim for the City is: "We aim to build and safeguard a fair, prosperous and open city where no-one is in poverty; where our citizens are well educated and take part in the decisions that affect them and where the cultural and religious differences between people are valued and celebrated." (2006) 2.7 This context demonstrates some of the key assets within Liverpool and the different pressures and issues that the City faces. Without an appropriate assessment of the potential risks of flooding, there is a danger that the success of the City and future developments will be jeopardized by flooding, causing far reaching damage to buildings, economy, image and people though loss of belongings and personal injury. Further detailed consideration of the level of flood risk in key development areas is provided in section 6. Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 5 - 3 Policy Context 3.1 There are a variety of planning documents that provide a broad context to planning and floodrisk, as it is a key cross-cutting issue. Planning Policy Statement 1: Delivering Sustainable Development2, provides the overarching principles for the planning system refers to the need to avoid new developments in areas at risk of flooding and sea-level rise. In addition, other guidance relating to different types of development such as PPS3: Housing, PPS6: Planning for Town Centres and PPG4: Industrial, Commercial Development and Small Firms need to be taken into account. The Supplement to PPS1 on Climate Change3 also needs to be considered, particularly with regard to mitigation