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Strategic Flood Risk Assessment

Merton Council (in partnership with Wandsworth Council) have produced an updated joint Level 1 (November 2020) and Level 2 (February 2021) Strategic Flood Risk Assessment (SFRA).

The National Planning Policy Framework1 (NPPF) and associated Planning Practice Guidance for Flood Risk and Coastal Change (PPG) set out the active role Local Planning Authorities (LPAs) should take to ensure that flood risk is understood and managed effectively and sustainably throughout all stages of the planning process. The NPPF outlines that Local Plans should be supported by a Strategic Flood Risk Assessment (SFRA) and LPAs should use the findings to inform strategic land use planning.

Level 1 SFRA

Merton Level 1 SFRA 2020

The Level 1 SFRA has collated and analysed the most up to date available flood risk data for all sources of flooding to provide an overview of flood risk across the study area. This has been used by Merton Council to inform the preparation of the Local Plan, including the application of the Sequential Test to site allocations.

The key updates to this revised Level 1 SFRA (2020) include:

  • River Wandle Climate Change Modelling (August 2017)
  • Online Flood Risk Mapping (to Support the Level 1 SFRA)
  • Areas at risk of perched groundwater in Merton
  • Further commentary on areas to safeguard for flood risk management, the cumulative impact of development, and opportunities to reduce the causes and impacts of flooding.

Online map

The mapping to support the Level 1 Strategic Flood Risk Assessment (SFRA) is provided in the Merton SFRA Online Map:

Merton SFRA online map

The maps help the user to easily understand the risk of flooding from the various sources including rivers, groundwater and surface water risk in any area of Merton and also provide information on historic flooding and geology. Instructions on how to use the mapping are provided in the User Guide and a list of data sources is included in the Data Register.

Online Map Data Register

Online Map User Guide

Level 2 SFRA

Merton Level 2 SFRA 2020

Merton Level 2 SFRA Appendix A Part 1

Merton Level 2 SFRA Appendix A Part 2

Merton Level 2 SFRA Appendix A Part 3

The Level 2 SFRA provides (a flood risk) screening assessment of each allocated site within the borough. It provides site specific recommendations on managing flood risk including the suitability of SuDS. This report will be used to inform development management decisions. Therefore it is essential that developers have consideration to the SFRA when submitting site specific flood risk assessments (FRAs) and drainage strategies to support planning applications.