New Welsh flood policy stalls at last minute

Last September, the Welsh government published its much anticipated update to Technical Advice Note (TAN) 15, a groundbreaking planning policy introduced in 2004 that required a precautionary approach to development in areas at risk of flood. The new policy was due to apply to all planning determinations made after 1 December 2021. The Flood Map for Planning (FMfP) was also published alongside the new TAN 15 to replace the Development Advice Map (DAM).

The new policy and new maps were published together just 12 weeks before implementation. For many planning professionals and local authorities this was the first time they could appreciate the significance of the changes. To their surprise, they realised that the new approach fundamentally called into question the viability of many sites and plans that had previously complied with the 2004 guidance.

While the content of the draft policy had been out for wide consultation, the draft flood maps had not been made available. Consequently, without being able to consider them alongside each other, many professionals did not appreciate or plan for the significance of the forthcoming changes. Many fear the revised TAN 15 could have a range of unintended consequences.

On 23 November 2021, Welsh government announced an 18-month suspension of the new TAN 15 just a week before it was due to take effect. Minster for climate change Julie James explained that suspension was 'to enable local planning authorities to consider fully the impact of the climate change projections on their respective areas'.

This requires flood risk avoidance and management to be balanced with maintaining sustainable and vibrant communities. For these reasons, the new TAN 15 moves away from the precautionary approach taken in the 2004 version, focusing instead on risk-based, plan-led decision making and climate change resilience.

Whereas the DAM had a single flood risk zone – Zone C – based on the extent of the 1-in-1,000-year extreme flood, the FMfP has two flood risk zones: Zones 2 and 3. This supports a more risk-based approach to decision-making, with the new TAN 15 setting out a policy that reflects differing levels of flood risk.

All FMfP zones also make allowance for the effects of climate change over the next century. This is a major departure from the current DAM, which shows only the present-day risk.

The last major change is that the FMfP incorporates the flood risk from surface water and small watercourses, in addition to that from rivers and sea. This will require development proposals to include a more comprehensive assessment of flood risk, although the justification tests do not apply to the surface water risk zones.

Figure 1 shows flood modelling for Cardiff by way of example. This accounts for significant flood defences throughout the city, but areas in pink are still predicted to flood to depths greater than 1m and it is thus unlikely that they can be developed.

The new mapping means that large areas previously designated as being at little or no risk of flooding – in particular coastal areas such as Cardiff, Newport and Port Talbot – are now in the highest risk category. This makes it very difficult, if not impossible, to justify development and regeneration in these locations.

Even where development is permissible in a flood zone, flooding needs to be within acceptable thresholds; for example, flood depths should be less than 600mm in the extreme 1-in-1,000-year plus climate change event. However, in many existing communities it may be impossible to comply with such requirements.

Neither do existing flood defences offer a solution, as they are almost never designed to protect against the extreme design event specified in the new TAN 15. Consequently, many defended zones will be overwhelmed, making it impossible or impractical for them to satisfy the acceptability criteria.

Figure 2 shows the example for the FMfP at Port Talbot. For simplicity this example does not include the surface water and small watercourse flood risk.

If rigidly applied, the policy set out in the new TAN 15 will result in flood blight in some towns and cities, where no new development or redevelopment of any type is permitted. This could have a major impact on placemaking, economic growth and the long-term sustainability of communities in some locations.

The problem is that the updated TAN and associated mapping effectively classify substantive areas of existing development as unsafe. This means that, in future, there will be no practical means in the planning system to secure new development to support and enhance existing communities, including in some cases development that makes these communities more resilient to the effects of climate change and flooding.

In the meantime, flood risk and development has never been more complex and technical. Planning and property professionals should check all potential development opportunities in Wales against both the DAM and FMfP. If they find that a site is in a flood zone, they are advised to seek the advice of a flood risk consultant at the earliest opportunity.

But fundamentally, while we can do a great deal to manage and mitigate the risk of flooding, avoidance is better than cure.