Last winter, flooding dominated the headlines for months, as families were forced from their homes at Christmas, entire communities were engulfed by flood waters and the UK was battered by storm after storm from the Atlantic Ocean.
The Environment Agency estimates that 7,700 homes and 3,200 commercial properties were flooded from December 2013 to March 2014. Politicians argued over whether flood defence funding had been cut or increased, and whether funding levels were sufficient to cope with the flooding expected in future.
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Victims complained that the root of the problems was development on floodplains. In fact, most of the flooded homes are likely to pre-date government policy on flood risk, and are at risk for entirely different reasons than those faced by planners today.
Today, planning policy steers development to sites at lowest risk of flooding and ensures that, where it must occur on floodplains, it is done safely.
Policy recognises that to prevent all development in flood-prone areas would blight existing communities. What is often forgotten, however, is that development offers opportunities, not just to provide new homes and businesses that are designed to be safe from flooding but also to reduce the risks to neighbouring communities (see CPD module, p38).
Evidence is mounting that the British climate is changing and flood risk increasing with it. Photo: Adrian Kingsley-Hughes
Arbitrarily restricting development in floodplain areas would condemn those already at risk to relying on public funding for flood defences, of which there will never be enough to reduce risks to satisfactory levels everywhere.
Planning applications in at-risk areas should be accompanied by a flood risk assessment to detail how the proposals satisfy planning policy with respect to flood risk and ensure that risk to neighbouring communities is not increased (and reduced where possible). The pervasive nature of flood waters, and the impact of local ground levels and building thresholds on determining whether flooding occurs, mean it is advantageous for flood risk to be considered from the outset.
A flood risk expert can provide a steer when development proposals are in their infancy, to avoid costly revisions at later stages. Furthermore, management of flood risk can work hand in hand with the provision of amenity space or environmental improvements, and should not just be seen solely as a problem to be engineered away at the eleventh hour.
The Met Office has confirmed that 2014 was the hottest year in the UK since records began in 1659, and eight of the 10 warmest years have occurred since 2002. A warmer atmosphere holds more moisture, so it is no surprise that five of the six wettest years since 1910 have been happened since 2000. Climate change is almost certainly affecting the frequency of extreme conditions.
The Met Office has confirmed that 2014 was the hottest year in the UK since records began in 1659, and eight of the 10 warmest years have occurred since 2002. A warmer atmosphere holds more moisture, so it is no surprise that five of the six wettest years since 1910 have been happened since 2000.
Planning policy requires developments to be made safe and allow for the impacts of climate change throughout their lifetime. Although online flood mapping datasets can be used to gain an initial understanding of flood risk, these do not account for the future impacts of climate change. Further investigation and discussion with the regulatory authorities is often required to understand how risk may change in future, and the implications for development and mitigation measures.
Government efforts to maintain flood protection in the face of a changing climate can also have impacts for those building in flood-prone areas.
In London, the Thames Estuary 2100 Plan (TE2100) sets out how the protection from the Thames Barrier and raised river walls will be maintained in future. As the sea level rises, the barrier will be required to let ever higher tides into London in response to extreme flood events. Over the coming century this will require corresponding increases in the height of the walls and banks that flank the Thames.
Developers of riverside sites will have to show how existing or new defences will withstand additional height in future.
The challenges of building sustainably in flood risk areas do not disappear with planning approval. Developers must ensure, through the flood defence consent process, that construction works do not harm sensitive river and tidal environments, interfere with flood protection or contravene the European Union Water Framework Directive.
As evidence mounts that the British climate is changing and flood risk increasing with it, sustainable management of flood risk can no longer be considered an optional extra in design and construction.
Ian Joyner is a flood risk consultant at CBRE
