More “exceptional” Flooding?

The record breaking rainfall of December 2015 has left damage and destruction across parts of the UK and catalysed a series of (seemingly endless) discussions as to whether we are seeing “unusual and exceptional storms” or whether we are witnessing the physical manifestation of climate change.

Whether the drivers here are man-made, a natural phenomenon or more likely a combination of both, it’s apparent that a shift in thinking is required if we are to better prepare and recover from similar circumstances in the future.

Over the last 10,000 years, our weather conditions and climate seem to have been relatively benign, stable and predictable. We have just had it confirmed, however, that in 2016 global temperatures are set to rise by more than one degree above pre-industrial levels; the prospect of irreversible and significant climate change is becoming ever more real. Previously, and quite understandably, mankind has so often chosen to live and build close to rivers to take advantage of clean drinking water; readily available fish; flatter, fertile terrain; and easy access to transport and trade networks. Aside from previously mentioned discussions on causation it’s becoming clear (and I’ll add that I’ve seen this first hand) that an established way of life for entire regions is becomingly increasingly disrupted.

Looking at the recent floods in quite simple terms these were the consequence of wave after wave of moisture laden warm air sweeping across the North Atlantic which then dropped a heavy cargo of intense rainfall on top of the United Kingdom. On top of an average of 230mm rainfall in the month across the whole UK, itself the highest for any month on record; 341mm fell in one day at Honister Pass in Cumbria, and 1 metre of rainfall fell in one month on Capel Curig in North Wales. The rain fell on ground that only has a limited capacity to store the water and slow it down. The run-off then preceded to find its way into our communities that were not high enough above the advancing floodwaters.

“Slowing the flow”, on the surface, seems a relatively simple fix; ensure that new build and new investment is placed higher than the level of the most aggressive and anticipated floods. This approach, however, of course raises some big questions.

We all have to work, live and adapt around a complicated legacy of buildings, homes, assets and communities which have grown and evolved over the centuries. Physically raising them up out of harmful flood waters is invariably not possible. Indeed, we have to understand each location’s priorities before effectively making the most of the measures and policies available to us. There is no set way to re-organise our buildings, assets and utilities that are vulnerable to flooding. To complement the design of buildings and infrastructure capable of withstanding flooding we need to further build in resilience and adaptation into existing measures such as traditional physical flood barriers, warnings, temporary evacuations and improved emergency planning. We should also begin to more readily encourage the use of, where possible, more radical solutions like buildings that can float in the event of flooding. Importantly, these all need to be flexible enough to easily be restored to more normal use to aid with recovery. Often the financial and social returns are very attractive from these protection systems with typically the benefits outweighing the costs by eight to one.

For some communities adaptation is not a viable reality. But in these places is there a willingness to move to a safer place on higher ground and effectively abandon these communities? Moreover, is there wider acceptance that this wholesale migration and building new cities in the years ahead will have to happen? It’s essential that we’ll all continue to work with communities to raise awareness to the impracticality of eliminating flooding altogether. Through constructive dialogue we can better educate communities not only about the implications of choosing to live on the waterfront, but also the effects of new measures and polices and how they pertain to minimising risk of life and maximising quality of life.

It is unlikely that the pattern of storms and flooding we have seen in the twentieth century will be a reliable benchmark for our current century. Regardless of the accuracy and impending reality of future forecasts it’s clear that the case for water-sensitive and resilient design for the built environment is stronger than ever. If we are to avoid loss of life and excessively costly destruction we will need to better blend sound, innovative engineering with the river catchment and coastline. It is imperative that we plan and build wisely, all the while being open for adaptation, change and commitment to appropriate resource. We must all collaborate in the future to step up and deal with the most worthwhile and important legacy flood protection matters.

David Wilkes, Global Flood Resilience leader at Arup