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Japan's experience with earthquakes has lessons for nations learning to live with floods

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Dr Mohammad Heidarzadeh is Assistant Professor in Civil and Environmental Engineering at Brunel University London

The intense rainfall from storms this winter has caused severe flooding in numerous cities across the UK. The storms have left at least eight people dead, and economic losses have been estimated at a few billion pounds. The government has responded by announcing flood defence spending will be doubled to £5.2 billion pounds over the next five years. Such severe flooding may seem like a rare event, but – as those living in the most flood-prone areas will tell you – it is not.

There was flooding to a similar if not greater extent between December 2013 and January 2014, which killed 17 people and cost £1.3 billion in economic losses. At the time the Met Office reported that it was the wettest Dececember-January period on record. There was also major flooding across the UK in 2016, and previously in 2009, 2007 and 2000, and flooding of lesser extent in other years as well.

What this suggests is that regularity of major flooding in the UK has dropped from every 15 to 30 years as it was over the 20th century, to between every two to seven years today.

More frequent major flooding puts unprecedented pressure on flood defences, with insufficient time and resources to recover between major events as in the past. We need to acknowledge that in the UK – as is the case elsewhere – flood defences are 20th century approaches now ill-suited to tackle what the 21st century is throwing at us.

Civil engineers have usually been employed to build “hard” structural solutions, such as more and higher concrete walls and soil embankments around rivers. But this may no longer be the best approach in the face of the recurring intense weather patterns and associated flooding. The fundamental assumptions that underpin structural solutions are that the environmental pressures they are built to meet do not substantially change over time. Clearly, this is no longer the case.

The UK government’s announcement of greater investment in flood defences is welcome, but this does not necessarily mean building longer and higher walls. What is needed is an integrated approach to flood defence that goes beyond using only structural solutions. Now, in the first decades of the century, the UK is in a period of transition that presents the opportunity to adjust our flood defences to the requirements of what this century’s climate will bring.

How Japan faced up to earthquakes

In the years before the second world war, Japan faced the issue of building its resilience to earthquakes. Japan experiences on average at least one or two earthquakes of magnitude 6.5 to 7 or greater every year. These earthquakes used to kill many thousands of people, but the average death toll has significantly decreased and has fallen to a few tens of people in recent years (with exceptions, such as the 1995 Kobe earthquake, and the earthquake that caused the 2011 tsunami).

This has been achieved through a programme that combines technological development and significant public involvement. Japan holds annual and even monthly earthquake drills in schools and other public and private sector organisations. There is also earthquake education in schools and public information campaigns as well as nationwide earthquake warning messages through mobile phones. In earthquake or tsunami danger zones there are detailed signs to indicate areas at risk.

These social approaches are pillars of Japan’s earthquake resilience programme, standing alongside the cutting-edge technological development of recent decades, such as seismic base isolation and motion-absorbing technology.

The main outcome of Japan’s public education campaign has been that most people understand that while earthquakes cannot be prevented, their destructive impacts can be minimised, and that everyone has a role to play. This has been instrumental in bringing government and public together in building a more earthquake-resilient society. In fact, Japan has turned its massive challenge to an opportunity: protecting its economy and communities against earthquakes while becoming the leader in earthquake-mitigation technologies: state-of-the-art know-how that it exports to the world.

Many nations worldwide struggle with flooding. Along with the Netherlands, Britain has been a pioneer in flood defence infrastructure engineering. This is an opportunity for the UK to not only address its flooding problems properly at home, but also to build on its existing reputation and take a leading role worldwide in developing new flood defence technology.

 

Facing up to floods at home

To begin with, an information campaign is needed to inform the public of the new reality. Everyone should know that flooding is now a frequent risk – it may have been affordable to get flooded every 15 to 30 years in the past, but few can bear the expense of being flooded out of their home every few years as is possible now. 

The public must be properly informed that it is not technically possible to achieve zero flooding – and that in order to protect larger, denser populations in towns and cities, it may be necessary to accept flooding in other areas.

Politicians and experts need to be honest with communities living in flood-prone areas that, given the current circumstances and the potential for the situation worsening in the future, there will need to be a managed retreat from areas deemed to too difficult or costly to protect.

And people need to understand that pouring concrete everywhere is not the answer. Greater walls and hard surface areas serve only to guide rainwater into the river channel, which then subsequently bursts its banks. Instead, it would be better to strive to keep surfaces in their natural, permeable states through more widespread use of sustainable drainage systems.

The storms that sweep across Europe form thousands of miles away in the Atlantic Ocean or in the deserts of North Africa – highlighting the importance of international cooperation to identify and coordinate actions to minimise the effects of global warming. At home, regular flood drills and flood education combined with flood signage in communities at risk are avenues that need to be pursued seriously.

In the medium and long term, these efforts may help everyone understand that flooding is not a rare occurrence nor a one-off problem to be solved, but a natural phenomenon to be lived with. Flooding cannot be prevented, but the way we approach it can bring relief, and opportunities, for our communities and economy.The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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