Just when you thought you'd seen enough of risk assessments, along comes another one. This is the riskbased sequential test, which directs developers and authorities towards sites with a low risk of flooding. It makes flood risk a material consideration to be given appropriate weight in determining planning applications as well as in preparing development plans.
A draft PPG 25 Development and Flood Risk was published a year ago and recently revised to take account of last autumn's severe floods, consultation responses and the House of Commons committee report on flood plan development.
In announcing the revised draft, environment minister Nick Raynsford said: 'The revision toughens and sharpens the precautionary riskbased focus of the original draft.'
Only four weeks had been allowed for further consultation, Raynsford added, 'because this is an urgent matter on which new guidance is required without delay'.
PPG 25 will oblige architects to advise clients of their new responsibilities and the possible vulnerability of their land to flooding. They will also have to be alert to the effects that this guidance will have on particular sites when development plans are reviewed, especially on housing land allocations. This will be easier said than done, for several reasons.
There are two important areas of uncertainty and a considerable likelihood of policy conflict for many potential development sites. The uncertainty arises from a lack of scientific agreement on the potential effects and seriousness of climate change, for which reason the matter is to be reviewed in three years' time.
Areas of conflict arise from the risk-based sequential tests. These will inevitably direct new developments towards sites with a low flood risk or those with no risk at all, unless the need is demonstrably exceptional.
The requirement for new developments to be targeted at brownfield rather than greenfield sites is likely to throw up its own conflicts. The Thames Gateway is a case in point.
Large areas of development land are likely to fall well within the 100-year flood zones of the Thames estuary.
(The Thames barrier is designed to meet the criterion only until 2030).
Interestingly, the government has no statutory duty to protect land or property from flooding, but it is responsible for producing national strategic guidance and flood defence measures. The Environment Agency can only intervene with limited discretionary power to target defence measures at existing development.
The primary responsibility for safeguarding land and other property rests with the owner. This extends to ensuring the adequate drainage of land to prevent negative impacts on neighbouring land.
PPG25 stresses the importance of the precautionary approach, aimed at avoiding flood risk entirely wherever possible and to manage it elsewhere.
Although the guidance does not advocate a complete ban on building in flood-risk areas, there is great emphasis on developers taking responsibility for providing adequate information on flood risk in support of any planning application.
According to the draft, developers will have to demonstrate an awareness of flood risk, any consequential constraints on the proposed development and alternative means of mitigation. Where such development is unavoidable, developers will be expected to contribute to the cost of flood defence works. PPG 25 suggests the conditions may be attached to permissions to prevent the commencement of development until flood alleviation works have been completed.
Architects will have to learn more about how to hold water run-off from new surfaces and roofs, permeable and retentive car-parking surfaces, balancing ponds and all the rest.
Expect more water features to crop up in landscaping schemes.
But planning is a balancing act and PPG 25 introduces yet another factor into the balance. Flood risk will now have to be weighed up against meeting house-building targets, brownfield land objectives and the urban regeneration policies of the urban White Paper. And for many sites, getting planning permission w ill be even harder.
Brian Waters is principal of The Boisot Waters Cohen Partnership Tel. 020 7828 6555 email: brian@bwcp. co. uk.