1.1. Overview

The National Planning Policy Framework’s (NPPF) accompanying Flood Risk and Coastal Change Planning Practice Guidance (PPG) highlights the role of Local Planning Authorities (LPAs) to utilise a risk-based approach to understand and manage flood risk from all sources. This includes the risks to and from surrounding areas in the same flood catchment. As a result, LPAs are required to produce Strategic Flood Risk Assessments (SFRA) to inform the preparation of Local Plans. The PPG defines a SFRA as:

“a study carried out by one or more LPAs 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.”

The West London Boroughs of Barnet, Brent, Ealing, Harrow, Hillingdon and Hounslow (hereinafter ‘the Boroughs’) have commissioned the production of a joint Level 1 SFRA. The overarching aim of this SFRA is to provide the evidence base for ensuring development is steered away from areas identified most at risk from various flood sources, reducing the risk of flooding to its residents and buildings. This review is required to provide an update to existing borough specific SFRAs, which were predominantly completed in 2008.The Greater London Authority’s (GLA) Drain London Project grouped the six boroughs together, as Groups 1 and 2. From this grouping, the Boroughs have since formed the North West London Flood Risk Management Strategic Partnership group. The group aims to provide the Boroughs with the platform to deliver their Lead Local Flood Authority (LLFA) requirements of the Flood & Water Management Act (FMWA) 2010 and the Flood Risk Regulations (FRR) 2009. The group has representation on the Thames Regional Flood and Coastal Committee (RFCC), a committee established by the EA to promote joined up thinking and actions to manage flood risk throughout the Thames catchment area and administer relevant funding streams.

The combined area features several cross-boundary Environment Agency-designated Main Rivers, including the Dollis Brook, Duke of Northumberland’s River, River Brent, River Crane, River Colne, River Lee, River Pinn, River Thames and Yeading Brook. These rivers cross boroughs that make up six of the seven local authorities that form the West London Alliance (WLA). Due to these established associations, groupings, and shared borough boundaries, a joint SFRA is beneficial for all Boroughs. This document and mapping will provide consistency and clarity, and will enable sign-posting to common policies and requirements. A joint SFRA also enables the identification of potential improvements which the Boroughs are recommended to adopt and enforce through their future Local Plans to improve local flood risk whilst promoting sustainable development.

1.2. Objectives

The purpose of this Level 1 SFRA is to provide a strategic overview of all forms of flood risk throughout the study area, now and in the future. This document and associated mapping delivered as part of the SFRA, will be used as an evidence base by the Boroughs to inform the preparation of Local Plans, including the application of the sequential test to future site allocations. In addition to providing an evidence base, the SFRA will provide each Borough with robust information which should be used to:

  • Determine the variations in risk from all sources of flooding across their areas.
  • Inform the Sustainability Appraisal so that flood risk is fully taken into account in assessment of Local Plans.
  • Provide the evidence needed to inform the undertaking of the Sequential Test in determining the land use allocations in accordance with the NPPF, and how to apply the Sequential Test for windfall sites within the boroughs.
  • Develop policies to manage the effects of climate change and flood risk from all sources.

It is intended that this Level 1 SFRA will provide a starting point for improved strategic and partnership working by considering the scope for future common approaches for managing flood risk across the study area. This reflects the challenges posed to the Boroughs through the need for increased development.

1.3. Document Structure

This SFRA is published in a website format. The website is broken down into six sections, as described below:

  • Section 1 (Introduction) provides an overview of the purpose and objectives of the SFRA. This section provides context for having a joint SFRA, with a summary of the current status of each Boroughs Local Plans.
  • Section 2 (Planning and Policy Framework) provides an overview of the relevant national, regional, and sub-regional policies relating to flood risk and associated requirements. An overview of each Boroughs key local policies is included.
  • Section 3 (Sources and Assessment of Flood Risk) provides an overview of the flood risk from all sources across the study area, including climate change implications where this information is available. This section introduces the West London SFRA interactive map which depicts the various flood risks across the study area.
  • Section 4 (Flood Risk Assessment Guidance) provides guidance for developers undertaking Flood Risk Assessments (FRA) for proposed development sites within any of the six boroughs. Borough-specific guidance is included where any key differences exist. This section explains the Sequential Test and Exception Test and how to apply the boroughs’ method for the split of Flood Zone 3, including the Functional Floodplain.
  • Section 5 (Policy Recommendations) provides a set of recommended site-specific and strategic policies. These recommendations are based on the findings of this SFRA, which the Boroughs are advised to incorporate into future versions of their Local Plans and/or associated guidance documents. An overview of the potential impact that future growth could have on flood risk across the study area is provided. Any opportunities for improved strategic flood risk management methods, including possible funding mechanisms, to assist with Boroughs growth delivery requirements are also highlighted.
  • Section 6 (Review and Next Step) provides a summary of the proposed update schedule for the SFRA (the technical content and the mapping). Recommendations for the need to conduct a Level 2 SFRA are also included based upon the findings of flood risk screening assessments of borough site allocations (included in Appendix A).

This SFRA has appendices and additional content as described below:

  • Appendix A (SFRA Level 2 – Screening Assessment) contains a spreadsheet that summarises the screening assessments of site allocations within each of the boroughs.
  • The Web Map index also summarises the list of all data sources used in the web map, including data origin information and any key limitations.
  • Checklists contains templates which developments must refer to when submitting Flood Risk Assessments and/or Drainage Strategies.

1.4. Local Plans

Table 1-1 below provides a status summary of the Borough-specific Local Plans at the time of writing (March 2018).

Table 1-1. Local Plan Status Summary

Local Plan Document Suite Local Plan Core Strategy Adoption / Publication Date
Barnet Local PlanSeptember 2012
Brent Local PlanJuly 2010
Ealing Local PlanApril 2012
Harrow Local PlanFebruary 2012
Hillingdon Local PlanNovember 2012
Hounslow Local PlanSeptember 2015

This SFRA provides recommended policy improvements based on the findings presented throughout this document. These policy recommendations are for future updates of Boroughs Local Plans and are designed to aid the mitigation of flood risks and deliver sustainable future development. Further details are provided in Section 5.2.

1.5. Planning Application Considerations

The guidance provided in this Level 1 SFRA is used, in part, in the assessment of planning applications. However, flooding is only one of many considerations in assessing a planning application. Measures that are identified as potentially acceptable in addressing flood issues may not be acceptable for other planning reasons under certain circumstances. For example, raising floor levels to mitigate against flood risk may result in design requirement issues, necessitating alternative solutions to address the flood risk. For further information, contact the relevant LPA.