Flood defence – a watertight investment

On 9 May 2019, BBC News published an article on climate change and how flood planners across the country ‘must prepare for the worst’.

A prediction is cited; “global temperature could rise between 2C and 4C by 2100”. We know that even the low end of this scale is bad. Aiming to bring climate change reduction to as high as 1.5C is the best target we can hope for, but still has uncertain consequences, not just for England, but for the rest of the UK and the world.

The science behind global warming and flooding is relatively simple. Warmer planet, warmer air, warmer seas, meaning more evaporation and moisture held in the air, which will result in more intense rainstorms. Warmer seas also mean we will see more ice melting from polar regions and higher sea levels. This is all very difficult to predict locally; when might a flood or a tsunami occur in my neighbourhood? But the trends are becoming easier to confirm with certainty, thanks to satellite information and powerful computer models.

The article goes on to deliver some frightening statistics and one-liners:

  • Properties built in the floodplain will double over the next 50 years
  • Communities would need help to ‘move out of harm’s way’
  • £1bn a year would need to be spent on flood management
  • More intense bursts of rain and continuing coastal erosion is expected
  • Rising seas will ‘swamp’ homes
  • Hundreds of key sites in England will be at risk of floods

I support the proposal that the only way to deal with flooding in the long term is to combat climate change. This approach will reduce flooding and improve a whole host of other consequences.

We must reverse the effects of industrialisation with new technologies, learn from the mistakes of the past, and learn to co-operate and co-exist globally. Refocus our priorities as human beings; perpetual growth is not sustainable. As a country, we have much to emulate and learn from around the world, because we can share knowledge and select from best practice.

Awareness has improved regarding the harmful and overwhelming presence of plastic in our oceans and on our mountains. The spiralling and devastating effects of deforestation have been known for years, but new consequences are coming to light as our understanding of tree communities develops.

We also learnt this week in a UN biodiversity report that human beings could be responsible for the extinction of over 1 million species on this planet. That is an eighth of all species to disappear; not a legacy to be proud of for future generations. Climate scientists talk of tipping points, points beyond which the possibility of reversal disappears, and the penalties of accelerated climate change are too devastating to think about. Which tipping point will put humans on that extinction list?

However, the biodiversity report does suggest that “it is not too late to make a difference, but only if we start now at every level from local to global”. This requires an overhaul of economic systems and a shift in political and social mindsets. Governments have to implement drastic change now to avoid a “dire future” in 10-20 years when “food and climate security [is] in jeopardy”. These are the same changes as the fight against climate change. Whether or not you are a climate change sceptic, the economics make sense.

Considering all the above, it is the responsibility of industrialised nations to make rapid and significant changes. We have largely ignored the problem over the last 50 or more years with too little change. Many of the consequences are here already and will undoubtedly get worse before they get better, and they will only get better if we make these big, necessary changes. This means that in respect of flooding, we will see more and more of it over the next 30 years, regardless of whether we secure a more positive future for generations to come.

For the next few decades and more, in the absence of local reliable strategic defences, the only real option for flood risk is to design and implement appropriate flood defences for existing buildings. New build requires a design approach to eliminate flood risk, perhaps with elevated structures and sacrificial resilient elements.

The pressure to build on land not at flood risk will increase land values in such areas. But the skill to bring an existing asset at flood risk out of that risk and back into viable long-term profitable use – by careful design and appropriate construction methods – is a more environmentally friendly and sustainable approach.

Written by Ian Paton, head of Oxford PBC for flood risk consultancy
May 2019


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Ian Paton

Partner, building surveying

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Ian Paton