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Planning Advice Note PAN 69
Planning and Building Standards Advice on Flooding

FLOOD PREVENTION SCHEMES AND PLANNING

LEGISLATION AND PROCEDURES

101. Flood prevention schemes (FPS) may be proposed by local authorities under the Flood Prevention (Scotland) Act 1961. Increasingly the schemes consider a wide range of measures to manage the risk of flooding in a sustainable way. As SPP 7 says, this may include channel improvements, watercourse restoration, managed realignment, culvert opening and provision of additional flood water storage, as well as the more traditional approach of walls and embankments where necessary. Under the 1961 Act, a proposed flood prevention scheme must be widely advertised by the Council and a notice served on those people whose interest may be affected so that they have an opportunity to consider the proposal and object. The scheme also has to be submitted to Scottish Ministers for confirmation. Under the Act confirmed schemes attract flood prevention grant, subject to satisfying the required criteria. In future, they may also need authorisation under the provisions of the WEWS Act (see paragraphs 140-142).

102. Flood prevention schemes also require planning permission. As local authority developments this is usually sought under the provisions of the Town and Country Planning (Development by Planning Authorities) (Scotland) Regulations 1981, (usually referred to as the Notice of Intention to Develop (NID) procedure), though if measures are in the area of another planning authority a normal planning permission will be needed. If there are objections to a NID scheme it has to be notified to the Scottish Ministers who may call it in for their own decision.

103. With planning and flood prevention requirements to be satisfied, including two consultation exercises and potentially two public inquiries, there is much to recommend an interdepartmental team for delivering a FPS. This will probably be the surest way to deliver the best possible scheme, meet all the requirements and resolve the issues to everyone's satisfaction. If it is likely that two public inquiries will be required, the benefits of a conjoined inquiry should be considered. Some of the benefits of a combined approach are illustrated in Case Study 2 on the White Cart flood prevention scheme and Case Study 5 on the Tay flood prevention scheme at Perth.

104. The planning application has to include greater detail than the submission required under the Flood Prevention Act. In some cases, objections to the flood prevention scheme may be raised which might have been averted had more detailed information been made available to the public. Some authorities have found that carrying out the two consultations in parallel can be helpful in providing the information sought by members of the public. Alternatively, if the FPS consultation and submission are carried out prior to consultation on the planning application, it may prove helpful to provide accompanying information with the FPS consultation, for example providing clarity on materials and finishes likely to be used on walls. This combined approach should also help the public to understand how the requirements interact. The figure below sets out the main stages of both and how a combined approach may be taken to scheme preparation.

DESIGN ISSUES

105. The development plan may set out the overall planning policy context for a flood prevention scheme and should be taken into account from the early stages of scheme preparation. The most relevant parts are likely to be: sites proposed for development or redevelopment within the area covered by the scheme, policies for areas designated because of their environmental importance; design policies for the built environment and policies for natural heritage. For example, the policies for a conservation area may specify high standards of design and materials. Plans may also contain specific policies which address the design of the FPS.

Watercourse Flood Management

106. Flood prevention schemes may now more accurately be referred to as 'flood management schemes' and may typically involve a range of measures designed to manage the flow of flood water through a catchment in a way which minimises the likelihood of flooding in a sustainable way. These can include flood water storage, re-routing, run-off reduction measures and flood walls/embankments. Several of these may be used as components of the same scheme. See Case Studies 2, 3 and 4 for examples which combine more than one protection measure.

"The most sustainable of solutions are likely to be those that address the issue of run-off at source. The introduction (or re-introduction) of storage into the rainfall-runoff relationship can be particularly effective when applied near to the point where runoff begins. Storage is also very effective further down the system if it is sufficiently large in proportion to the problem..."
Learning to Live with Rivers, Institution of Civil Engineers, 2001

107. It is not sustainable for existing buildings to flood but generally a range of measures should be used to support the natural functioning of the watercourse. The range of measures for flood prevention and management could include:

• River restoration - This involves returning it to a more natural state, with the intention of slowing down the flow of a reach of river. It can work particularly well upstream of a developed area, where the water level will back up and push the water into storage on natural plains along the restored reach. (summarised from Learning to Live with Rivers)
• Flood water storage areas - creating, preserving and enhancing natural flood meadows and washlands or salt marshes and mud flats may have a role to play in attenuating flooding and may also contribute to environmental objectives. The temporary use of land for flood water storage will not normally require planning permission though it is likely to be a component of a flood prevention scheme. Any storage facility designed for a capacity of more than 25,000m ³ of water above the level of adjacent ground will come under the Reservoirs Act 1975. Scottish Executive research to investigate and quantify the potential of natural flood storage is expected to report in 2005.
• Flood walls - The height and engineering qualities of a flood wall will be specified to meet flood prevention objectives but the appearance of the wall and possibly its precise location will be material to the consideration of the NID. Facing materials can do much to fit the design of a wall into its environment and where there is some flexibility in the location of the wall its local impact can be reduced. In some urban areas, natural materials such as stone, brick, sand, soil or wood may be preferable from a design perspective rather than artificial materials such as concrete, asphalt or plastic, but the integrity of the flood prevention measures must not be compromised.
• Flood gates - flood gates may be used where it is necessary to maintain access through the wall or embankment and are a permanent feature in the environment. When they are open, which will be most of the time, they should be as unobtrusive as possible. Utilitarian designs should be avoided in public areas.
• Embankments - embankments are a good way of blending a flood barrier into the environment. The steepness of the embankment's gradient will to a large extent determine its visual impact.
• Channel creation, restoration or realignment- this is likely to be an engineering operation and fall within the scope of the NID. Opportunities should be sought to provide habitat enhancement, new habitats and amenity areas.
• Other techniques - proposals to change the forestry and agricultural practices within a catchment, or the use of existing reservoirs to attenuate peak flows are unlikely in themselves to be matters for the planning system. If it is proposed to demolish rather than protect buildings, demolition will require planning permission in conservation areas or if the building is listed.

Coast Protection Works

108. Measures to protect the coastal zone against flooding, wave damage and erosion include:

• Hard engineering solutions such as sea walls, groins, jetties, dykes. See Case Study 6 on Rothesay sea defences.
• Soft engineering solutions such as
• • replenishment of beaches or dunes;
  • managed realignment - reclaimed coastal areas outside settlements which are subject to flooding can be restored as coastal wetlands by removing walls or relocating them further inland. For an example, see Case Study 7 on coastal realignment at Nigg Bay, Cromarty Firth. Coastal realignment also has the potential to create a buffer zone which may absorb the energy of storms and rising sea levels.

109. An unintentional breach in defences in a coastal or estuary area, for example due to lack of maintenance, can have serious consequences. Planning authorities should make sure they have up to date information on the condition of coastal defences as they affect any planning application.

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