Draft Flood Risk Supplementary Planning Document

Appendix 3 - 'Developed' areas within 1 in 20 year flood outline

The approach to development in these areas recognises the importance of pragmatic planning solutions that will not unnecessarily 'blight' areas of existing development, the significance of the undeveloped land around them and the potential opportunities to reinstate areas which can operate as Functional Floodplain through re-development to provide space for floodwater and reduce risk to new and existing development.

Where redevelopment is proposed in these areas schemes should not increase the vulnerability classification of the site. All schemes must result in a net reduction in flood risk and ensure that floodplain storage and flow routes are not affected. This can be achieved through a combination of on and off-site measures.

  • Reducing the land use vulnerability;
  • Seeking opportunities to ensure there is no increase or achieve a reduction in the number of people at risk (e.g. avoiding conversions and rebuilds of properties that result in an increase in the number of residential dwellings);
  • Maintaining or reducing built footprint
  • Removing non-floodable structures
  • Raising finished floor levels;
  • Reducing surface water runoff rates and volumes from the site;
  • Increasing floodplain storage capacity through the provision of direct/indirect floodplain compensation and voids
  • Reducing impedance to floodwater flow and restoring flood flow paths;
  • Incorporating flood resilience and/or resistance measures;
  • Ensuring development remains safe for users in time of flood (this may refer to the timely evacuation of properties prior to the onset of flooding in accordance with an individual Flood Warning and Evacuation Plan for the site).

Proposals for a change of use or conversion to a higher vulnerability classification will not be permitted. Basements, basement extensions, conversions of basements to a higher vulnerability classification will not be permitted.

These areas are particularly sensitive to the cumulative impact of minor development and therefore the Council will require such proposals to consider, in detail, the flood risk implications of the development. Proposals for minor development in these areas should not increase flood risk elsewhere by not impeding flow or reducing storage capacity. This could be achieved for example by ensuring that flow routes are not hindered by buildings, providing direct or indirect flood compensation storage or the incorporation of voids under raised floor levels. Whilst it is acknowledged that full compensation may not be possible on all minor developments, an applicant must be able to demonstrate that every effort has been made to achieve this and provide full justification where this is not the case.

In these areas, the Council will consider making Article 4 Directions in future to remove permitted development rights and ensure that flood risk can be fully assessed through the planning application process.