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Building on floodplains in light of Global Warming

Recent flooding in the UK has highlighted the problem of building on floodplains; a result of the incessant housing demand and progressively reduced land availability. There are in excess of 5 million people now living in flood risk areas, which combined with increasingly variable predicted weather conditions is only ever likely to result in future catastrophic flooding as experienced by those in the floods of June 2007.

Flooding in low land areas adjacent to rivers has been a pattern in evidence for many millennia, and can still be seen today, with many of the major settlements adjacent to main freshwater arteries, e.g. London, Cardiff. However as the effects of Global warming are expected to begin, with increased sea levels, greater frequency of storm surges etc, within the next few decades, we need to be adequately prepared to deal with the consequences.

Those individuals currently living on floodplains will find an increase in the regularity/ frequency of flood risk alerts, and evasive flooding. These persons will find themselves in untenable, uninsurable positions and thus after succession of periodic flooding will discourage even the mightiest of individual from re-populating the settlement.

Rising sea levels will continue to worsen the situation, swelling rivers, streams and waterways alike, resulting in a greater proportion of the population at risk to flooding. It is anticipated that Government intervention will be limited and prioritised to those areas of high densities, and thus discard more remote, smaller populations.

It is unfeasible and uneconomical to restrict flooding in low-lying floodplains throughout the UK in face of such drastic global altercations. It is also expected that the scarce supply of funding that is available will be prioritised to those settlements of greatest densities. Therefore we need to switch our focus from attempting to prevent flooding, to an acceptance of its inevitability and thus look to minimise its impact through greater, more inventive management techniques. These may include:

  • Adaptive buildings - salt resistant plaster on the ground floor walls, flooring surfaces, which can be removed and replaced easily to anti-back flow valves to prevent water rising up drains and installing airbricks with removable covers.
  • Drainage- SUDS (Sustainable urban drainage systems), which act as permeable paving to use of Aco drains, placed at opening thresholds, and in paths etc.
  • Soft engineering schemes- planting trees/ vegetation aligned on riverbanks, interspersed on floodplains to use of soak ways in more rural areas to limit/reduce water load into the sewage system at times of heavy rainfall.


In the long term, if nothing is done, in terms of improved protection, it may be foreseen, after a new flooding event; villages/ towns will become either isolated, or deserted. The ‘doomsday’ scenario of mass evacuation and fragmented communities, on a scale not too dissimilar to that witnessed during summer 2005, when Hurricane Katrina hit New Orleans; may become a reality without significant Governmental intervention.

Solving these new challenges requires a fresh approach; currently emphasis is on providing embankments to ‘hold back’ the waters. It is advised however that we need to instead look at our understanding of how water interrelates with our environment, taking into account such issues as groundwater, overland flow, infiltration rates and soil bearing capacity. The aim of which is to result in engineering solutions such as providing dense vegetation and surface water gullies, to control, manage and regulate our fresh water supplies.

It is hoped that the new Flood and Water Management bill 2009, the Governments response to the Pitt Review will go some way to addressing these issues to ensure our homes are designed and managed to minimise and mitigate the impact of flooding in these high-risk areas.